An exploration of the protective mechanism of esmolol on the heart of septic rats based on the beta-adrenergic signaling pathway.

An exploration of the protective mechanism of esmolol on the heart of septic rats based on the beta-adrenergic signaling pathway. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research An exploration of the protective mechanism of esmolol on the heart of septic rats based on the beta-adrenergic signaling pathway. Pan Li, Jingzhuo Liu, Xintong Zhang, Lingling Zhen, Yingzhen Wang, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-16199/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Cardiac dysfunction caused by sepsis is a serious challenge for ICU doctors. Previous studies showed that the beta adrenergic receptor (β- AR) signaling pathway system can cause abnormal heart function. Studies have also shown that esmolol, a type of beta blocker, participates in the beta receptor desensitization that occurs. This study intends to further explore the specific mechanism of esmolol in the protection of cardiac function. Method In this study, rats were randomly divided into three groups: Sham (sham operation group), CLP (cecal ligations and function group) and ES (esmolol group). The three groups were divided into two subgroups: A and B. Group A was used to observe the number of survival days. Group B was divided into 6 hours,12 hours and 24 hours according to the time after the operation to take samples, and the rats were sacrificed after the corresponding intervention. The inflammatory factors and the factor of β receptor pathway were measured by different methods. And the hypothesis was verified by statistical methods. Results ELISA tests demonstrated that the levels of inflammatory factors CA,TNF-α, and IL-6, as well as G protein pathway factors AC, CAMP and PKA in the CLP group were significantly higher than those in the Sham group, while those factors in the ES group were significantly lower than those in the CLP group, cardiac function factor cTnI is the opposite. Western blotting showed that, compared with the CLP group, the inflammatory proteins MYD88 and NF-KB in the myocardial tissue of the ES group were significantly decreased, while the levels of the beta receptor pathway proteins β1-AR, β2-AR, β-arrestin-1 and β-arrestin-2 were significantly increased, and the result of β-ARK was the opposite. Pathological results and immunofluorescence results indicated that the degree of myocardial cell injury in the ES group was significantly improved compared with that in the CLP group. Conclusion Esmolol has a protective effect on the heart by selectively preventing the pathologic signaling pathway mediated by overactivation of beta receptors while retaining the normal signaling pathway. Critical Care & Emergency Medicine Sepsis Myocardial dysfunction Esmolol β-adrenergic signaling pathway Receptor desensitization Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Introduction Sepsis is a life-threatening organ dysfunction caused by disordered host response to infection, which is manifested as systemic inflammatory response and host autoimmune injury[ 1 ]. At the same time, it is complicated with multiple organ dysfunction syndrome, most of which are circulatory, immune and metabolic dysfunctions. A previous study showed that sepsis not only causes great damage to the body, but also makes the social burden significantly increased[ 2 ][ 3 ]. It also increases the hospitalization rate and mortality of patients year by year. More than 52, 000 people die of sepsis each year[ 4 ]. A recent study in the United States has shown that 12% of sepsis cases are fully preventable[ 5 ]. The mechanism of sepsis has also been an interest of researchers for a long time. Sepsis is now considered to be an alternate process of immunosuppression and hyperimmunity[ 6 ][ 7 ]. Past research has shown that G-protein coupled receptors (GPCRs) can be combined with various bioactive molecules, including extracellular signals from hormones, neurotransmitters, chemical hormones and other environmental stimuli, and that GPCRs induce cellular gene transcription changes via different signaling pathways, participating in the regulation of almost all of the physiological processes. A study of 601 subjects showed that catecholamines are an important predictor of cardiovascular mortality, MI and stroke[ 8 ]. The body, in the case of any damage, poisoning or other cause of injury or stress state, releases a large amount of catecholamines , resulting in systemic hypercatabolism, hyperdynamic circulation and abnormal magnification of inflammatory response, leading to multiple organ dysfunction. Over-activated catecholamines can induce calcium overload and can cause changes in signal pathway transduction. From activating the β-AR-Gs-AC-cAMP-PKA pathway to activating the β-AR-Gs-Ca2-CaMKII pathway, cardiomyocyte apoptosis is promoted and leads to sepsis-induced myocardial dysfunction (SIMD). SIMD is one of the most important causes of the poor prognosis of sepsis. β-arrestin is a kind of header protein and signal transduction regulatory protein found in the process of purification of β adrenergic receptor kinase 1(β-ARK1)[ 9 ][ 10 ][ 11 ]. It has many physiological functions. It has been proven that it can not only participate in the occurrence of β receptor desensitization in septic cardiac dysfunction, but also activates the ERK signal pathway by the activation of epidermis factor translocation, thus inhibiting the apoptosis of cardiomyocytes induced by continuous activation of β receptor and giving full play to the protective effect of the heart. Previous studies show that β-arrestin and β-ARK1 are two important factors involved in β-receptor desensitization[ 12 ]. When the agonist binds to β-AR, the agonist-activated β-AR binds to β-ARK1 and undergoes phosphorylation, which causes the conformational change of β-arrestin and the increase of affinity of β-arrestin to β-AR, this in turn inhibits the interaction between GPCRs and G protein, thus hindering the signal transduction of GPCRs [ 13 ][ 14 ]. β-arrestin is also directly involved in the degradation of second messenger cAMP, and the inhibition of downstream cAMP-dependent mitogen-activated protein kinase(MAPK)activation, thus promoting desensitization. A large number of studies have shown that a variety of factors are alone or jointly involved in β-arrestin induced β receptor internalization, that is, the β receptor on the surface of the cell membrane enters the membrane, which weakens the signal stimulation and leads to the desensitization of β receptor [ 15 ][ 16 ]. The endocytized receptor can be re-released into the cell membrane cycle to continue to receive stimulation, but also can be degraded by the related enzymes, being made completely defunct [ 17 ]. Esmolol, as an ultra-short-acting selective β 1 receptor blocker, has been confirmed, at home and abroad, to have cardiac protective effect, and to reduce the hospitalization rate and mortality of septic patients with cardiac dysfunction [ 18 ][ 19 ]. The results of animal experiments also confirmed that it could reverse left ventricular hypertrophy [ 20 ]. Human randomized controlled trials and other related studies have also shown that esmolol can improve the survival rate of septic patients and slow down the heart rate but does not affect the oxygen index [ 21 ]. It inhibits the β 1 receptor by competing for catecholamine binding sites on the surface of cardiomyocytes and suppressing the hypermetabolism of catecholamine over-activation in the whole body [ 22 ]. The purpose of this study was to explore the specific mechanism of esmolol in improving cardiac function from the organ, tissue and cellular levels, to find new targets and to provide theoretical support for clinical reduction of sepsis mortality and improvement of prognosis . Material And Methods 96 SPF male rats (250–300 g) were provided by the Experimental Animal Center of Lanzhou University School of Basic Medicine, animal license number: SCXK (Gan). The experiment was approved by the Experimental Animal Ethics Committee of the Second Affiliated Hospital of Lanzhou University. Animals Before examination, the rats were fed and watered freely in the laboratory at room temperature of 22 °C to 26 °C and humidity of 40–60%. The rats were fed adaptively for 1 week after 12 hours of light and dark cycles. The experimental animals were randomly divided into 3 groups (n = 72), namely, Sham group, CLP group and ES group, and 8 rats from each group were randomly selected for observation of the survival condition at 7 days. The remaining 24 rats were randomly divided into 6,12 and 24 h subgroups according to the experimental time, with 8 in each subgroup. Experimental Animal Model Rats were prepared by receiving no food for 12 hours (water given ad lib) and then 2% sodium pentobarpital was injected into the abdomen. The rats’ limbs were fixed in supine position, the abdomen was prepped and draped. An approximately 2 cm vertical incision was made in the abdomen and the abdominal cavity was entered layer by layer. The mesentery and cecum were mobilized and the distal 1/3 of the cecal artery was ligated with 4.0 silk suture. In the CLP and ES groups, the end of the cecum was perforated twice with a 20 gauge sterile needle and a small amount of intestinal contents extruded from the cecum into the abdominal cavity. In the Sham group, no artery ligation or perforation of the cecum was performed. The abdominal cavity was closed in layers. Animals received 20 mL/kg of normal saline as fluid resuscitation post operatively. The successful establishment of the model was marked by mental malaise, vertical hair, and secretion in the corners of the eyes. Laparotomy at the corresponding time point revealed a large amount of ascitic fluid and ligated blackened cecum adhesions, and foul smell. Internal jugular vein catheterization in rats and administration of drugs in experimental animals The skin of the left neck of the rats was prepped and draped then an incision was made from the upper left to lower right. The distal portion of the internal jugular vein was ligated, a “V” shaped incision was made using ophthalmologic scissors, and the jugular vein was cannulated with a catheter primed with heparin sodium (25U/mL). Blood return was used to indicate successful catheter placement. Once the catheter was secured to the distal ligature, 0.5 mL of heparin sodium was instilled. The incision was covered with wet gauze. In the sham group, saline infusion was continued for 6 hours. The ES group had continuous infusion of esmolol at a dose of 15 mg/kg/hr (1 mL/h), for a total of 6 hours. The animal’s symptoms and heart rate were monitored continuously during esmolol infusion and esmolol dose was adjusted over time based on observations. Post-infusion the catheters were removed, blood vessels ligated and incision sutured closed. Experimental Protocols The rats in each group were killed at the corresponding time point (6, 12, and 24 h). After thoracotomy, 4 mL blood samples were collected from the heart, at room temperature for 10 min, and then centrifuged at 2000 r/min for 5 min. The related biochemical indices were collected and stored at low temperature after loading. The heart was removed and the myocardial tissue was preserved in -80 °C cryopreservation box, and the homogenate and related biochemical indexes were to be detected. Detection of serum CA, TNF- α, IL-6, cTnI , AC, cAMP, and PKA levels by ELISA in rats Using ELISA kit (Jianglai, Shanghai, China) of CA, TNF-α, IL-6, cTnI ,AC, cAMP and PKA were used and operated in strict accordance with the instructions, and the absorbance was measured at 450 nm by using a microplate reader, and the standard curve was drawn to calculate the levels of the above factors . Western blot was used to detect the content of the inflammatory protein (MYD88, NF-KB) and the receptor-pathway proteins (β1-AR, β2-AR, βARK1, βarresttin-1, β-arresttin-2) in the myocardium . An appropriate amount of myocardial tissue was taken and centrifuged after tissue lysis, and the supernatant was taken. We used the BCA quantitative method, denaturing the protein and running the gel, transferring the mold and blocking with 5% skim milk at room temperature for 1.5 h. Then NF-KΒ (1: 500), MYD88 (1: 1000), β1-AR (1: 1000), β2 -AR (1: 1000), βARK (1 : 1000), β-arrestin1 (1: 500), β-arrestin2 (1: 1000), β-tublin (1: 20000), GAPDH (1: 10000) were diluted respectively and incubated in a refrigerator at 4 ° C overnight. The next day, the film was washed with TBST at room temperature 3 times, 10 min each time. As in the previous method, the secondary antibody (1: 2 000) was incubated at room temperature for 1 h, and developed with ECL working fluid after three washings. The signal was obtained by radiography equipment. Finally, ImageJ software was used for image analysis and processing, and the gray values of target protein and internal parameters were obtained. The relative content of the target protein is equal to the grey value of the target protein divided by the grey value of the internal parameters multiplied by 100% . The pathological observation of myocardial tissue Myocardial tissue was washed with saline 3 times, fixed with 10% neutral formaldehyde buffer, dehydrated, embedded, sliced, roasted, stained with paraffin and hematoxylin-E red, and the morphological changes were observed under light microscopy . Myocardial cell apoptosis under fluorescence microscopy Frozen sections were removed from the refrigerator and rewarmed. They were air dried, fixed, decolorized, washed, repaired and membranes broken up. Reagent 1 (TdT) and reagent 2 (dUTP) were added. The appropriate amount of reagent from the TUNEL kit(BestBio,Shanghai,China) was determined according to the number of slices and tissue size. Reagents 1 and 2 were mixed at 2 m 29 s to block endogenous peroxidase. Reagent 3 (converter-POD) was added to cover the tissue and develop DAB color. Sections were rinsed with tap water to stop the color development . Survival rate analysis The rats in the Sham group, CLP group and ES group were given normal diet after 6 hours, and the survival of each group was observed . Data analysis method Statistical analyses were done using the software Statistical Product for Social Sciences (SPSS; version 16.0, Chicago, IL, USA) and data plotted using GraphPad Prism 5.0 Software (San Diego, CA, USA). Differences among groups were tested using a one-way analysis of variance. Data are expressed as mean ± SEM. A p-value < 0.05 was considered statistically significant. Results Esmolol can reduce the inflammation of myocardial tissue in rats by inhibiting MYD88/ NF-KB pathway As shown in Figs. 1 , 2 , 3 , 5 , 6 and 7 , t he results of ELISA showed that the levels of serum CA,TNF- α,AC,cAMP,PKA and IL-6 in the CLP group and the ES group were significantly higher than those in the Sham group at 6 h, 12 h and 24 h after operation. The levels of those factors in the ES group were significantly lower than those in the CLP group at each time point (P < 0.05), while c TnI showed the opposite ( Fig. 4 ) . From the Western blot results of Figs. 8 and 9 , we can see that the expression levels of MYD88 and NF-KB in the ES group were significantly lower than those in the CLP group at 6, 12, and 24 hours after surgery . NF-KB protein expression was significantly higher than that in Sham group, and the expression of MYD88 and NF-KB protein in the ES group was significantly lower than that in the CLP group at each time point (P < 0.05). Esmolol can improve β-AR desensitization and signal transduction in cardiomyocytes by upregulating β1-AR, β2-AR, β-arrestin-1, and β-arrestin-2 protein expression The results of the Western blot show that the expression of β1-AR, β2-AR, β-arrestin-1, and β-arrestin-2 proteins in the CLP group and the ES group was significantly higher than that in the Sham group at 6 h, 12 h, and 24 h after operation. The expression of those proteins in the ES group was significantly lower than that in the CLP group at all time points (P < 0. 05). When compared longitudinally in chronological order, taking the CLP group as an example, we found that the expression of the β receptor pathway proteins in cardiomyocytes was the least at 12 h, followed by 6 h, and the expression of 24 h increased slightly, which was similar to that in the Sham group and the ES group. And βARK is completely different from the above proteins. This can be seen in Figs. 10 , 11 , 12 , 13 and 14 . The results of pathological tissue show that esmolol could reduce the degree of cardiac function damage in sepsis . As can be seen from the Fig. 15 (20×), the number of myocardial fibers in the CLP group decreased, the cells increased, and the transverse striations were blurred, broken, and irregular, with more inflammatory cells and a greater degree of tissue damage. The conditions in the ES group were slightly improved, and the Sham group had the least damage . The results of the Tunel staining suggest that esmolol can reduce the number of apoptotic cells and improve the myocardial injury . The results of Tunel staining are shown in Fig. 16 A (20×). We used the ImageJ software to quantitatively analyze the staining results, and the results are shown in Fig. 16 B. Compared with the sham group, the apoptotic area of the ES group and the CLP group were significantly increased. Compared with the CLP group, all subgroups of the ES group showed apoptotic area that is significantly reduced, suggesting esmolol can protect the myocardium to some extent . Esmolol can improve the survival rate of rats We used the log-rank test for survival analysis to 15 days to compare the rat survival curve of the Sham group, the CLP group, and the ES group. Using survival analysis at 15 days, the CLP group had the worst outcomes, and the Sham group had more rats survive (p < 0.01, see Fig. 17 ). Discussion Sepsis is a syndrome of immune imbalance involving multiple organs, which can lead to abnormalities in various organs of the body, among which the heart is the most severely damaged. Cardiac dysfunction induced by sepsis is the main cause of poor prognosis in patients with sepsis. The treatment of heart dysfunction has also become a major effort of clinicians. As a beta blocker with super-short effect , esmolol has been proven to have a protective effect on the heart many times, and is widely used in clinical practice. In this experiment, samples were obtained through the classical modeling method and drug intervention method, and relevant factors were detected, and the expected results were finally obtained . It is a well known technique to induce sepsis in the rat model by caecal ligation and puncture. It is also quite reasonable to apply it in this study. ELISA and Western Blot show that after CLP intervention, inflammatory cytokines CA, TNF-α, IL–6, MyD88 and NF-KB were significantly increased compared with the sham group, similar to a septic patient’s clinical pathological process of inflammatory activation. In the use of esmolol after the intervention, the content of the above inflammatory factors decreased, which was statistically significant. This indicates that esmolol has the effect of inhibiting the inflammatory response during sepsis, and can reduce the damage of inflammation to the body in the early stage. As for the cardiac function factor cTnI, compared with the CLP group , esmolol can increase the content of cTnI and improve the cardiac function of patients to a certain extent . Then,we studied the improvement of the beta receptor pathway with esmolol. As mentioned earlier in this article, beta receptors have positive inotropic effects that maintain the general physiological function of the heart by exciting GPCRs, that is β-AR—Gs—AC—cAMP—PKA pathway. However, when sepsis occurs, the early "sympathetic storm" causes the beta receptors to be continuously excited by catecholamines, and the GPCRs are transformed into the β-AR—Gs—Ca 2+ 一CaMKII pathway, which triggers apoptosis and cardiac dysfunction. It can be seen from ELISA results that, compared with the Sham group, the levels of G protein pathway factors AC, cAMP and PKA in the CLP group are significantly increased, while the levels of these factors are decreased in the ES group. This suggests that when sepsis occurred , esmolol, as beta blockers, can compete for catecholamine binding sites and inhibit the early onset of the "sympathetic storm" of sepsis. In other words, it can inhibit the pathologic apoptotic pathway mediated by catecholamines, thus playing a protective role on the heart . Previous data have shown that β-arrestin is involved in the process of reducing the incidence of left heart failure in patients and improving the cardiac function of patients with myocardial fibrosis to a certain extent [ 23 ][ 24 ]. There are also studies that show that β-arrestin can protect the myocardium in two ways. First, it is involved in the degradation, internalization, and circulation of β-AR mediated by G protein of the classical pathway, and it inhibits the apoptotic pathway induced by overactivated beta receptors in the early stage of sepsis. As previously stated, this desensitization cannot occur without both beta-arrestin and beta-ARK. Secondly, it can also act as a signaling molecule to participate in the beta receptor pathway, that is, it can bind to the beta receptor to activate the extracellular signal-regulated kinase (ERK)., inhibiting the proliferation and apoptosis of cardiomyocytes, thereby improving cardiac function. In this experiment, western blot showed that compared with the CLP group, the levels of β1-AR, β2-AR, β-arrestin-1 and β-arrestin-2 in the myocardial tissue of the ES group were significantly increased. It is suggested that in the early stage of sepsis, esmolol can activate the β-arrestin pathway to trigger the desensitization of beta receptors and prevent their over-activation thereby increasing the expression level of beta receptors and ultimately reducing the occurrence of cardiac dysfunction. Previous studies have shown that βARK is involved in the occurrence of myocyte hypertrophy [ 25 ], while the results of our experiment are just the opposite of the previous protein expression, indicating that esmolol can play a protective role in myocytes by reducing the expression of βARK . In addition, our pathological results showed that, among the myocardial cell injuries in each time period, the sham group was the least severe, followed by the ES group, and the CLP group was the most severe. It also visually demonstrated the cardiomyocyte protective effect of esmolol. We analyzed the apoptotic area of cardiomyocytes under electron fluorescence microscopy, and the immunofluorescence results also showed the same conclusion . Finally, as shown in the figure of survival rate analysis, esmolol did make a significant contribution to the improvement of rat mortality and indirectly indicating a protective function in cardiomyocytes . In general, from the perspective of desensitization of the β receptor in the pathogenesis of SIMD, we have explored its mechanism from the whole, tissue, and cellular levels. Taking βARK1, β-arrestin-1 and β-arrestin-2 as the key observational indicators, we have provided a new target for clinical treatment of SIMD, providing a new theoretical basis for esmolol to improve SIMD, and providing theoretical support for clinical reduction of sepsis mortality and improvement of prognosis. All of these have not been or only rarely been previously studied. Of course, there are still many deficiencies in this study. For example, the literature selected in this study is limited, and the data on the relationship between esmolol and beta receptor pathway is relatively insufficient. The theoretical aspect is not yet systematic and mature, it is still in the preliminary research stage. The experimental scheme is not perfect, and the sample size is limited. We also fail to face the above research from the genetic level. These defects will become our future research direction. Conclusion In summary, sepsis is a very complex pathophysiological process. Esmolol, as a kind of beta blocker, plays a huge role in the improvement of heart function during sepsis. The mechanism may be related to the fact that esmolol blocks the pathological signaling pathway induced by over-activation of beta receptors in sepsis. At the same time, it also preserves the physiological signaling pathway mediated by the beta-arrestin pathway, as well as improves the inflammatory response of myocardial cells and plays a role in the protection of the myocardial cells from multiple aspects. In the future, we should continue to explore the specific mechanism, providing new targets for the treatment of sepsis and new ideas for the better application of esmolol in clinical practice . Declarations Acknowlegements Not applicable Funding This work was supported by the Project fund of the Lanzhou University of Second Hospital(NO.CY-2018-MS03). Availability of data and materials All data generated or analyzed during this study are included in this published article. Author information 1)Affiliations Department of Critical Care Medicine, Lanzhou University Second Hospital,No. 82, Cuiyingmen,Chengguan District, Lanzhou City, Gansu Province , China: Pan Li,Jing-zhuo Liu,Xin-tong Zhang,Ling-ling Zhen,Ying- zhen Wang,Xiao-rong Dong,Bei Zhang Sun Yat-sen University Zhongshan School of Medicine No.74 Zhongshan 2nd Road, Guangzhou, China: Shu-hang Luo 2)Contributions PL, JZL and XTZ participated in data analysis and manuscript drafting, and LLZ contributed to the experimental design, YZW and XRD participated in animal modeling process and specimen acquisition, BZ and SHL participated in specimen detection and data processing. LM participated in manuscript revision for critical intellectual content, and the observation of the whole research process. Corresponding Author Li Ma, MD PhD, E-mail: [email protected] , Department of Critical Care Medicine, Lanzhou University Second Hospital,No. 82, Cuiyingmen,Chengguan District, Lanzhou City, Gansu Province , China. Ethics declarations The experiment was approved by the Experimental Animal Ethics Committee of the Second Affiliated Hospital of Lanzhou University. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. References Singer M, Deutschman C S, Seymour C W, et al. The third international consensus definitions for sepsis and septic shock (Sepsis-3)[J]. Jama, 2016, 315(8): 801-810. Zimmerman J E, Kramer A A, Knaus W A. Changes in hospital mortality for United States intensive care unit admissions from 1988 to 2012[J]. Critical care, 2013, 17(2): R81. Mayr F B, Yende S, Angus D C. Epidemiology of severe sepsis[J]. Virulence, 2014, 5(1): 4-11. Singer M, Inada-Kim M, Shankar-Hari M. 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Esmolol improves clinical outcome and tissue oxygen metabolism in patients with septic shock through controlling heart rate[J]. Zhonghua wei zhong bing ji jiu yi xue, 2015, 27(9): 759-763. Philip J L, Xu X, Han M, et al. Regulation of cardiac fibroblast-mediated maladaptive ventricular remodeling by β-arrestins[J]. PloS one, 2019, 14(7). Schlegel P, Reinkober J, Meinhardt E, et al. G protein-coupled receptor kinase 2 promotes cardiac hypertrophy[J]. PloS one, 2017, 12(7): e0182110. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-16199","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research","associatedPublications":[],"authors":[{"id":385634,"identity":"66e6f25f-2952-4cb9-9456-d09dac49d7f6","order_by":1,"name":"Pan Li","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Pan","middleName":"","lastName":"Li","suffix":""},{"id":385635,"identity":"bc4116d6-818b-4f05-a254-04cb9f741bf4","order_by":2,"name":"Jingzhuo Liu","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jingzhuo","middleName":"","lastName":"Liu","suffix":""},{"id":385636,"identity":"9c8b8997-4478-41f2-9249-19cb61b8ee56","order_by":3,"name":"Xintong Zhang","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xintong","middleName":"","lastName":"Zhang","suffix":""},{"id":385637,"identity":"ad180faf-77c1-4f89-883e-d41c1cd36d28","order_by":4,"name":"Lingling Zhen","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Lingling","middleName":"","lastName":"Zhen","suffix":""},{"id":385638,"identity":"ee9fe30e-8eb4-4f75-897d-16bfa1733028","order_by":5,"name":"Yingzhen Wang","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yingzhen","middleName":"","lastName":"Wang","suffix":""},{"id":385639,"identity":"fd1a1452-132f-459a-a888-cf540be67f62","order_by":6,"name":"Xiaorong Dong","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaorong","middleName":"","lastName":"Dong","suffix":""},{"id":385640,"identity":"b342473f-f1d7-479b-a877-99d6ed7b70f5","order_by":7,"name":"Bei Zhang","email":"","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bei","middleName":"","lastName":"Zhang","suffix":""},{"id":385641,"identity":"4c87057f-43bc-4a75-a3fd-d2f7aa97b27a","order_by":8,"name":"Shuhang Luo","email":"","orcid":"","institution":"Sun Yat-sen University Zhongshan School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Shuhang","middleName":"","lastName":"Luo","suffix":""},{"id":385642,"identity":"d12b4911-ee3e-45bc-96dc-baba4fba8c9f","order_by":9,"name":"Li Ma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIie3LMQrCMBTG8dRA4vAg6yvqHQIFFRS8SrvYpYqjQ4eCUBfRq3gEIdAp7h11cXYSp2Lo4BjjJpg/PHjD9yPE5/vdxiB4+1BnghBuviVEKlcielp26hz7keI3JOtJUvDzyUrCfSZpViEMFZkj0WlSwDK2EqnBENaSCoNSJQWCtJJZSxqEaBOUGDQORIIhi9LMKGUYFA4ENVvRxR4BFaPjuEqjEjI7ETt6pNljOhPb7bW+55PBgWs7IaQ7er7/2Bz7sDfxy+eNz+fz/Xcvqkk1EQjAQZwAAAAASUVORK5CYII=","orcid":"","institution":"Lanzhou University Second Hospital","correspondingAuthor":true,"prefix":"","firstName":"Li","middleName":"","lastName":"Ma","suffix":""}],"badges":[],"createdAt":"2020-03-02 15:33:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-16199/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-16199/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":603279,"identity":"b8fc0804-7e95-46d2-9558-42805c9a8192","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":48945,"visible":true,"origin":"","legend":"Assessment of CA levels in plasma as measured by ELISA. Date are expressed as concentration(pg.ml-1);black lines indicate medians ± interquartile range. all groups,n=8.*p＜0.05.CLP cecal ligation and puncture, ES esmolol 1.5mg.kg-1 .h-1.","description":"","filename":"Figure1CA1.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 1-CA-1.tif"},{"id":603280,"identity":"49411811-1bee-4ba9-8d87-775134548cc5","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":44787,"visible":true,"origin":"","legend":"Assessment of TNF-α levels in plasma as measured by ELISA.","description":"","filename":"Figure2TNF.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 2-TNF.tif"},{"id":603281,"identity":"ea9faf46-8962-4399-acd7-294faf42fbb3","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":45621,"visible":true,"origin":"","legend":"Assessment of IL-6 levels in plasma as measured by ELISA.","description":"","filename":"Figure3IL6.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 3-IL-6.tif"},{"id":603282,"identity":"63873b9d-f04a-4b29-b71b-c29328e59d91","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":46810,"visible":true,"origin":"","legend":"Assessment of cTNI levels in plasma as measured by ELISA.","description":"","filename":"Figure4cTNI.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 4-cTNI.tif"},{"id":603283,"identity":"d771ea9a-ffff-4034-9fbd-de06633dbeb6","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":335373,"visible":true,"origin":"","legend":"Assessment of AC levels in plasma as measured by ELISA.","description":"","filename":"Figure5AC.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 5-AC.tif"},{"id":603284,"identity":"4b9073e1-4bc1-4a28-970c-029a69c01d63","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":44970,"visible":true,"origin":"","legend":"Assessment of cAMP levels in plasma as measured by ELISA.","description":"","filename":"Figure6CAMP.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 6-CAMP.tif"},{"id":603285,"identity":"6e0e2d00-c1e1-48f7-8b11-f566217efd49","added_by":"auto","created_at":"2020-03-05 20:40:41","extension":"tif","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":46609,"visible":true,"origin":"","legend":"Assessment of PKA levels in plasma as measured by ELISA.","description":"","filename":"Figure7PKA.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 7-PKA.tif"},{"id":603286,"identity":"b29f738d-3915-4c3d-a825-448472c72335","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":315035,"visible":true,"origin":"","legend":"Western blot analysis of protein of MyD88 expression in the myocardium. Proteins were obtained from myocardium (n=8) prepared from all experimental rat groups. A typical western blot is shown above the histogram. Densitometric analysis (n=8) was used to calculate the normalized protein ratio. Data are expressed as median ± standard deviation range. Upper edges of error bars represent the maximum value in each group. \n*: Sham VS CLP, p\u003c0.05. #:CLP VS ES, p\u003c0.05. CLP: cecal ligation and puncture, ES: esmolol","description":"","filename":"Figure8MyD88.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 8-MyD88.tif"},{"id":603287,"identity":"bc0c4cf3-26b8-4243-af5e-9521e21d9a39","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":776230,"visible":true,"origin":"","legend":"Western blot analysis of protein of Nf-kB expression in the myocardium.","description":"","filename":"Figure9NFkB.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 9-NF-kB.tif"},{"id":603288,"identity":"726ae2d3-8f2d-442c-b4e4-af40b49f4500","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":705379,"visible":true,"origin":"","legend":"Western blot analysis of protein of β-ARK1 expression in the myocardium.","description":"","filename":"Figure10ARK1.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 10-ARK 1.tif"},{"id":603289,"identity":"8d2220f1-2c35-4701-841f-c7d90dc503fa","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":800072,"visible":true,"origin":"","legend":"Western blot analysis of protein of β1-AR expression in the myocardium.","description":"","filename":"Figure11AR1.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 11-AR1.tif"},{"id":603290,"identity":"db54bd43-2031-490a-bdf1-c89375a71e50","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":671380,"visible":true,"origin":"","legend":"Western blot analysis of protein of β2-AR expression in the myocardium.","description":"","filename":"FIgure12AR2.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/FIgure 12-AR2.tif"},{"id":603291,"identity":"7ce31f31-7374-4a89-9781-60bce00d242e","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":725671,"visible":true,"origin":"","legend":"Western blot analysis of protein of β-arrestin-1 expression in the myocardium.","description":"","filename":"Figure13arrestin1.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 13-arrestin-1.tif"},{"id":603292,"identity":"ea9f980a-6307-4f6b-b430-21588ab2b1bc","added_by":"auto","created_at":"2020-03-05 20:40:42","extension":"tif","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":643311,"visible":true,"origin":"","legend":"Western blot analysis of protein of β-arrestin-2 expression in the myocardium.","description":"","filename":"Figure14arrestin2.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 14-arrestin-2.tif"},{"id":603293,"identity":"aaf9d9e2-987b-4bf9-8a4e-204330e06697","added_by":"auto","created_at":"2020-03-05 20:40:43","extension":"tif","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":4285543,"visible":true,"origin":"","legend":"The figure shows pathological results, which are sorted chronologically from left to right, and sorted chronologically from top to bottom for different groups. From the figure, we can see different degrees of infiltration of inflammatory cells and myocardial cell damage(HE×20).","description":"","filename":"Figure15Pathology.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 15-Pathology.tif"},{"id":603294,"identity":"4784999f-3485-4b93-9782-aa308dbf3679","added_by":"auto","created_at":"2020-03-05 20:40:43","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":534488,"visible":true,"origin":"","legend":"A) This figure shows the immunofluorescence of the 24h group, in which cells in the DAPI group that were stained with green fluorescer represent apoptotic cells, and the more staining, the more serious the myocardial cell damage(20×); B) This is a graph of our quantitative analysis using imagine J statistics","description":"","filename":"fig16.png","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/fig16.png"},{"id":603295,"identity":"7927c90f-c8d4-4778-8ecd-ee00a6b9670f","added_by":"auto","created_at":"2020-03-05 20:40:43","extension":"tif","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":278598,"visible":true,"origin":"","legend":"We used the log-rank test for survival analysis to 15 days to compare rat survival curve of Sham group, CLP group, ES group. Using survival analysis at 15 days, the CLP group had the worst outcomes, and the Sham group performed that they had more rats can survive (p \u003c 0.01).","description":"","filename":"Figure17.tif","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/Figure 17.tif"},{"id":13492282,"identity":"ada2a339-1244-4a4a-9283-0d108da004e4","added_by":"auto","created_at":"2021-09-16 22:31:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5518790,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-16199/v1/26a3b241-de42-4f0a-8ac8-5fe37543025a.pdf"}],"financialInterests":"","formattedTitle":"An exploration of the protective mechanism of esmolol on the heart of septic rats based on the beta-adrenergic signaling pathway.","fulltext":[{"header":"Introduction","content":" \u003cp\u003eSepsis is a life-threatening organ dysfunction caused by disordered host response to infection, which is manifested as systemic inflammatory response and host autoimmune injury[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. At the same time, it is complicated with multiple organ dysfunction syndrome, most of which are circulatory, immune and metabolic dysfunctions. A previous study showed that sepsis not only causes great damage to the body, but also makes the social burden significantly increased[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e][\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It also increases the hospitalization rate and mortality of patients year by year. More than 52, 000 people die of sepsis each year[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. A recent study in the United States has shown that 12% of sepsis cases are fully preventable[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The mechanism of sepsis has also been an interest of researchers for a long time. Sepsis is now considered to be an alternate process of immunosuppression and hyperimmunity[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e][\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ePast research has shown that G-protein coupled receptors\u003c/span\u003e (GPCRs) can be combined with various bioactive molecules, including extracellular signals from hormones, neurotransmitters, chemical hormones and other environmental stimuli, and that GPCRs induce cellular gene transcription changes via different signaling pathways, participating in the regulation of almost all of the physiological processes. A study of 601 subjects showed that catecholamines are an important predictor of cardiovascular mortality, MI and stroke[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe body, in the case of any damage, poisoning or other cause of injury or stress state, releases a large amount of catecholamines\u003c/span\u003e, resulting in systemic hypercatabolism, hyperdynamic circulation and abnormal magnification of inflammatory response, leading to multiple organ dysfunction. Over-activated catecholamines can induce calcium overload and can cause changes in signal pathway transduction. From activating the β-AR-Gs-AC-cAMP-PKA pathway to activating the β-AR-Gs-Ca2-CaMKII pathway, cardiomyocyte apoptosis is promoted and leads to sepsis-induced myocardial dysfunction (SIMD). SIMD is one of the most important causes of the poor prognosis of sepsis.\u003c/p\u003e \u003cp\u003eβ-arrestin is a kind of header protein and signal transduction regulatory protein found in the process of purification of β adrenergic receptor kinase 1(β-ARK1)[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e][\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e][\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It has many physiological functions. It has been proven that it can not only participate in the occurrence of β receptor desensitization in septic cardiac dysfunction, but also activates the ERK signal pathway by the activation of epidermis factor translocation, thus inhibiting the apoptosis of cardiomyocytes induced by continuous activation of β receptor and giving full play to the protective effect of the heart. Previous studies show that β-arrestin and β-ARK1 are two important factors involved in β-receptor desensitization[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eWhen the agonist binds to β-AR, the agonist-activated β-AR binds to β-ARK1 and undergoes phosphorylation, which causes the conformational change of β-arrestin and the increase of affinity of β-arrestin to β-AR, this in turn inhibits the interaction between GPCRs and G protein, thus hindering the signal transduction of GPCRs\u003c/span\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e][\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eβ-arrestin is also directly involved in the degradation of second messenger cAMP, and the inhibition of downstream cAMP-dependent mitogen-activated protein kinase(MAPK)activation, thus promoting desensitization. A large number of studies have shown that a variety of factors are alone or jointly involved in β-arrestin induced β receptor internalization, that is, the β receptor on the surface of the cell membrane enters the membrane, which weakens the signal stimulation and leads to the desensitization of β receptor\u003c/span\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e][\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe endocytized receptor can be re-released into the cell membrane cycle to continue to receive stimulation, but also can be degraded by the related enzymes, being made completely defunct\u003c/span\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eEsmolol, as an ultra-short-acting selective β 1 receptor blocker, has been confirmed, at home and abroad, to have cardiac protective effect, and to reduce the hospitalization rate and mortality of septic patients with cardiac dysfunction\u003c/span\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e][\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe results of animal experiments also confirmed that it could reverse left ventricular hypertrophy\u003c/span\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eHuman randomized controlled trials and other related studies have also shown that esmolol can improve the survival rate of septic patients and slow down the heart rate but does not affect the oxygen index\u003c/span\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eIt inhibits the β 1 receptor by competing for catecholamine binding sites on the surface of cardiomyocytes and suppressing the hypermetabolism of catecholamine over-activation in the whole body\u003c/span\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe purpose of this study was to explore the specific mechanism of esmolol in improving cardiac function from the organ, tissue and cellular levels, to find new targets and to provide theoretical support for clinical reduction of sepsis mortality and improvement of prognosis\u003c/span\u003e.\u003c/p\u003e "},{"header":"Material And Methods","content":" \u003cp\u003e96 SPF male rats (250\u0026ndash;300\u0026nbsp;g) were provided by the Experimental Animal Center of Lanzhou University School of Basic Medicine, animal license number: SCXK (Gan). The experiment was approved by the Experimental Animal Ethics Committee of the Second Affiliated Hospital of Lanzhou University.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eAnimals\u003c/h2\u003e \u003cp\u003eBefore examination, the rats were fed and watered freely in the laboratory at room temperature of 22\u0026nbsp;\u0026deg;C to 26\u0026nbsp;\u0026deg;C and humidity of 40\u0026ndash;60%. The rats were fed adaptively for 1 week after 12 hours of light and dark cycles. The experimental animals were randomly divided into 3 groups (n\u0026thinsp;=\u0026thinsp;72), namely, Sham group, CLP group and ES group, and 8 rats from each group were randomly selected for observation of the survival condition at 7 days. The remaining 24 rats were randomly divided into 6,12 and 24\u0026nbsp;h subgroups according to the experimental time, with 8 in each subgroup.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eExperimental Animal Model\u003c/h2\u003e \u003cp\u003eRats were prepared by receiving no food for 12 hours (water given ad lib) and then 2% sodium pentobarpital was injected into the abdomen. The rats\u0026rsquo; limbs were fixed in supine position, the abdomen was prepped and draped. An approximately 2\u0026nbsp;cm vertical incision was made in the abdomen and the abdominal cavity was entered layer by layer. The mesentery and cecum were mobilized and the distal 1/3 of the cecal artery was ligated with 4.0 silk suture. In the CLP and ES groups, the end of the cecum was perforated twice with a 20 gauge sterile needle and a small amount of intestinal contents extruded from the cecum into the abdominal cavity. In the Sham group, no artery ligation or perforation of the cecum was performed. The abdominal cavity was closed in layers. Animals received 20\u0026nbsp;mL/kg of normal saline as fluid resuscitation post operatively.\u003c/p\u003e \u003cp\u003eThe successful establishment of the model was marked by mental malaise, vertical hair, and secretion in the corners of the eyes. Laparotomy at the corresponding time point revealed a large amount of ascitic fluid and ligated blackened cecum adhesions, and foul smell.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eInternal jugular vein catheterization in rats and administration of drugs in experimental animals\u003c/h2\u003e \u003cp\u003eThe skin of the left neck of the rats was prepped and draped then an incision was made from the upper left to lower right. The distal portion of the internal jugular vein was ligated, a \u0026ldquo;V\u0026rdquo; shaped incision was made using ophthalmologic scissors, and the jugular vein was cannulated with a catheter primed with heparin sodium (25U/mL). Blood return was used to indicate successful catheter placement. Once the catheter was secured to the distal ligature, 0.5\u0026nbsp;mL of heparin sodium was instilled. The incision was covered with wet gauze. In the sham group, saline infusion was continued for 6 hours. The ES group had continuous infusion of esmolol at a dose of 15\u0026nbsp;mg/kg/hr (1\u0026nbsp;mL/h), for a total of 6 hours. The animal\u0026rsquo;s symptoms and heart rate were monitored continuously during esmolol infusion and esmolol dose was adjusted over time based on observations. Post-infusion the catheters were removed, blood vessels ligated and incision sutured closed.\u003c/p\u003e \u003c/div\u003e \n\n\u003ch2\u003eExperimental Protocols\u003c/h2\u003e\n \u003cp\u003eThe rats in each group were killed at the corresponding time point (6, 12, and 24\u0026nbsp;h). After thoracotomy, 4\u0026nbsp;mL blood samples were collected from the heart, at room temperature for 10\u0026nbsp;min, and then centrifuged at 2000 r/min for 5\u0026nbsp;min. The related biochemical indices were collected and stored at low temperature after loading. The heart was removed and the myocardial tissue was preserved in -80\u0026nbsp;\u0026deg;C cryopreservation box, and the homogenate and related biochemical indexes were to be detected.\u003c/p\u003e \u003ch2\u003e \u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eDetection of serum CA, TNF- α, IL-6, cTnI\u003c/span\u003e, \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eAC, cAMP, and PKA\u003c/span\u003e \u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003elevels by ELISA in rats\u003c/span\u003e\u003c/h2\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eUsing ELISA kit (Jianglai, Shanghai, China) of CA, TNF-α, IL-6, cTnI ,AC, cAMP and PKA were\u003c/span\u003e used and operated in strict accordance with the instructions,\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eand the absorbance was measured at 450\u0026nbsp;nm by using a microplate reader, and the standard curve was drawn to calculate the levels of the above factors\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eWestern blot was used to detect the content of the inflammatory protein (MYD88, NF-KB) and the receptor-pathway proteins (β1-AR, β2-AR, βARK1, βarresttin-1, β-arresttin-2) in the myocardium\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eAn appropriate amount of myocardial tissue was taken and centrifuged after tissue lysis, and the supernatant was taken. We used the BCA quantitative method, denaturing the protein and running the gel, transferring the mold and blocking with 5% skim milk at room temperature for 1.5\u0026nbsp;h. Then NF-KΒ (1: 500), MYD88 (1: 1000), β1-AR (1: 1000), β2 -AR (1: 1000), βARK (1 : 1000), β-arrestin1 (1: 500), β-arrestin2 (1: 1000), β-tublin (1: 20000), GAPDH (1: 10000) were diluted respectively and incubated in a refrigerator at 4 \u0026deg; C overnight. The next day, the film was washed with TBST at room temperature 3 times, 10\u0026nbsp;min each time. As in the previous method, the secondary antibody (1: 2 000) was incubated at room temperature for 1\u0026nbsp;h, and developed with ECL working fluid after three washings. The signal was obtained by radiography equipment. Finally, ImageJ software was used for image analysis and processing, and the gray values of target protein and internal parameters were obtained. The relative content of the target protein is equal to the grey value of the target protein divided by the grey value of the internal parameters multiplied by 100%\u003c/span\u003e.\u003c/p\u003e \u003ch2\u003e \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eThe pathological observation of myocardial tissue\u003c/span\u003e \u003c/h2\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eMyocardial tissue was washed with saline 3 times, fixed with 10% neutral formaldehyde buffer, dehydrated, embedded, sliced, roasted, stained with paraffin and hematoxylin-E red, and the morphological changes were observed under light microscopy\u003c/span\u003e.\u003c/p\u003e \u003ch2\u003e \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eMyocardial cell apoptosis under fluorescence microscopy\u003c/span\u003e \u003c/h2\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eFrozen sections were removed from the refrigerator and rewarmed. They were air dried, fixed, decolorized, washed, repaired and membranes broken up. Reagent 1 (TdT) and reagent 2 (dUTP) were added. The appropriate amount of reagent from the TUNEL kit(BestBio,Shanghai,China) was determined according to the number of slices and tissue size. Reagents 1 and 2 were mixed at 2\u0026nbsp;m 29\u0026nbsp;s to block endogenous peroxidase. Reagent 3 (converter-POD) was added to cover the tissue and develop DAB color. Sections were rinsed with tap water to stop the color development\u003c/span\u003e.\u003c/p\u003e \u003ch2\u003e \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eSurvival rate analysis\u003c/span\u003e \u003c/h2\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe rats in the Sham group, CLP group and ES group were given normal diet after 6 hours, and the survival of each group was observed\u003c/span\u003e.\u003c/p\u003e \u003ch2\u003e \u003cspan type=\"BoldSmallCaps\" class=\"BoldSmallCaps\" name=\"Emphasis\"\u003eData analysis method\u003c/span\u003e \u003c/h2\u003e \u003cp\u003eStatistical analyses were done using the software Statistical Product for Social Sciences (SPSS; version 16.0, Chicago, IL, USA) and data plotted using GraphPad Prism 5.0 Software (San Diego, CA, USA). Differences among groups were tested using a one-way analysis of variance. Data are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SEM. A p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \n\n"},{"header":"Results","content":" \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eEsmolol can reduce the inflammation of myocardial tissue in rats by inhibiting MYD88/ NF-KB pathway\u003c/h2\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eAs shown in\u003c/span\u003e Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e,\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e,\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e,\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003et\u003c/span\u003ehe results of ELISA showed that the levels of serum CA,TNF- α,AC,cAMP,PKA and IL-6 in the CLP group and the ES group were significantly higher than those in the Sham group at 6\u0026nbsp;h, 12\u0026nbsp;h and 24\u0026nbsp;h after operation. The levels of those factors in the ES group were significantly lower than those in the CLP group at each time point (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while c\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eTnI showed the opposite (\u003c/span\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e)\u003c/span\u003e. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eFrom the Western blot results of\u003c/span\u003e Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e,\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ewe can see that the expression levels of MYD88 and NF-KB in the ES group were significantly lower than those in the CLP group at 6, 12, and 24 hours after surgery\u003c/span\u003e. NF-KB protein expression was significantly higher than that in Sham group, and the expression of MYD88 and NF-KB protein in the ES group was significantly lower than that in the CLP group at each time point (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003ch2\u003e \u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eEsmolol can improve β-AR desensitization and signal transduction in cardiomyocytes by upregulating β1-AR, β2-AR, β-arrestin-1, and β-arrestin-2 protein expression\u003c/span\u003e \u003c/h2\u003e \u003cp\u003eThe results of the Western blot show that the expression of β1-AR, β2-AR, β-arrestin-1, and β-arrestin-2 proteins in the CLP group and the ES group was significantly higher than that in the Sham group at 6\u0026nbsp;h, 12\u0026nbsp;h, and 24\u0026nbsp;h after operation. The expression of those proteins in the ES group was significantly lower than that in the CLP group at all time points (P\u0026thinsp;\u0026lt;\u0026thinsp;0. 05). When compared longitudinally in chronological order, taking the CLP group as an example, we found that the expression of the β receptor pathway proteins in cardiomyocytes was the least at 12\u0026nbsp;h, followed by 6\u0026nbsp;h, and the expression of 24\u0026nbsp;h increased slightly, which was similar to that in the Sham group and the ES group. And βARK is completely different from the above proteins. This \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ecan be seen in\u003c/span\u003e Figs.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e,\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e and \u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eThe results of pathological tissue show that esmolol could reduce the degree of cardiac function damage in sepsis\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eAs can be seen from the\u003c/span\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e(20\u0026times;), the number of myocardial fibers in the CLP group decreased, the cells increased, and the transverse striations were blurred, broken, and irregular, with more inflammatory cells and a greater degree of tissue damage. The conditions in the ES group were slightly improved, and the Sham group had the least damage\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eThe results of the Tunel staining suggest that esmolol can reduce the number of apoptotic cells and improve the myocardial injury\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThe results of Tunel staining are shown in\u003c/span\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e16\u003c/span\u003eA\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e(20\u0026times;). We used the ImageJ software to quantitatively analyze the staining results, and the results are shown in\u003c/span\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e16\u003c/span\u003eB. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eCompared with the sham group, the apoptotic area of the ES group and the CLP group were significantly increased. Compared with the CLP group, all subgroups of the ES group showed apoptotic area that is significantly reduced, suggesting esmolol can protect the myocardium to some extent\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eEsmolol can improve the survival rate of rats\u003c/h2\u003e \u003cp\u003eWe used the log-rank test for survival analysis to 15 days to compare the rat survival curve of the Sham group, the CLP group, and the ES group. Using survival analysis at 15 days, the CLP group had the worst outcomes, and the Sham group had more rats survive (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01, see Fig.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e "},{"header":"Discussion","content":" \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eSepsis is a syndrome of immune imbalance involving multiple organs, which can lead to abnormalities in various organs of the body, among which the heart is the most severely damaged. Cardiac dysfunction induced by sepsis is the main cause of poor prognosis in patients with sepsis. The treatment of heart dysfunction has also become a major effort of clinicians. As a beta blocker with super-short effect\u003c/span\u003e, esmolol \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ehas been proven to have a protective effect on the heart many times, and is widely used in clinical practice. In this experiment, samples were obtained through the classical modeling method and drug intervention method, and relevant factors were detected, and the expected results were finally obtained\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eIt is a well known technique to induce sepsis in the rat model by caecal ligation and puncture. It is also quite reasonable to apply it in this study. ELISA and Western Blot show that after CLP intervention, inflammatory cytokines CA, TNF-α, IL\u0026ndash;6, MyD88 and NF-KB were significantly increased compared with the sham group, similar to a septic patient\u0026rsquo;s clinical pathological process of inflammatory activation. In the use of\u003c/span\u003e esmolol \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eafter the intervention, the content of the above inflammatory factors decreased, which was statistically significant. This indicates that\u003c/span\u003e esmolol \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ehas the effect of inhibiting the inflammatory response during sepsis, and can reduce the damage of inflammation to the body in the early stage. As for the cardiac function factor cTnI, compared with the CLP group\u003c/span\u003e, esmolol \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ecan increase the content of cTnI and improve the cardiac function of patients to a certain extent\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThen,we studied the improvement of the beta receptor pathway with\u003c/span\u003e esmolol. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eAs mentioned earlier in this article, beta receptors have positive inotropic effects that maintain the general physiological function of the heart by exciting GPCRs, that is\u003c/span\u003e β-AR\u0026mdash;Gs\u0026mdash;AC\u0026mdash;cAMP\u0026mdash;PKA pathway. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eHowever, when sepsis occurs, the early \"sympathetic storm\" causes the beta receptors to be continuously excited by catecholamines, and the GPCRs are transformed into the\u003c/span\u003e β-AR\u0026mdash;Gs\u0026mdash;Ca\u003csup\u003e2+\u003c/sup\u003e一CaMKII \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003epathway, which triggers apoptosis and cardiac dysfunction. It can be seen from ELISA results that, compared with the Sham group, the levels of G protein pathway factors AC, cAMP and PKA in the CLP group are significantly increased, while the levels of these factors are decreased in the ES group. This suggests that when sepsis occurred\u003c/span\u003e, esmolol, \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eas beta blockers, can compete for catecholamine binding sites and inhibit the early onset of the \"sympathetic storm\" of sepsis. In other words, it can inhibit the pathologic apoptotic pathway mediated by catecholamines, thus playing a protective role on the heart\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ePrevious data have shown that β-arrestin is involved in the process of reducing the incidence of left heart failure in patients and improving the cardiac function of patients with myocardial fibrosis to a certain extent\u003c/span\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e][\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eThere are also studies that show that β-arrestin can protect the myocardium in two ways. First, it is involved in the degradation, internalization, and circulation of β-AR mediated by G protein of the classical pathway, and it inhibits the apoptotic pathway induced by overactivated beta receptors in the early stage of sepsis. As previously stated, this desensitization cannot occur without both beta-arrestin and beta-ARK. Secondly, it can also act as a signaling molecule to participate in the beta receptor pathway, that is, it can bind to the beta receptor to activate the extracellular signal-regulated kinase (ERK)., inhibiting the proliferation and apoptosis of cardiomyocytes, thereby improving cardiac function. In this experiment, western blot showed that compared with the CLP group, the levels of β1-AR, β2-AR, β-arrestin-1 and β-arrestin-2 in the myocardial tissue of the ES group were significantly increased. It is suggested that in the early stage of sepsis, esmolol can activate the β-arrestin pathway to trigger the desensitization of beta receptors and prevent their over-activation thereby increasing the expression level of beta receptors and ultimately reducing the occurrence of cardiac dysfunction. Previous studies have shown that βARK is involved in the occurrence of myocyte hypertrophy\u003c/span\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003ewhile the results of our experiment are just the opposite of the previous protein expression, indicating that esmolol can play a protective role in myocytes by reducing the expression of βARK\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eIn addition, our pathological results showed that, among the myocardial cell injuries in each time period, the sham group was the least severe, followed by the ES group, and the CLP group was the most severe. It also visually demonstrated the cardiomyocyte protective effect of esmolol. We analyzed the apoptotic area of cardiomyocytes under electron fluorescence microscopy, and the immunofluorescence results also showed the same conclusion\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eFinally, as shown in the figure of survival rate analysis, esmolol did make a significant contribution to the improvement of rat mortality and indirectly indicating a protective function in cardiomyocytes\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eIn general, from the perspective of desensitization of the β receptor in the pathogenesis of SIMD, we have explored its mechanism from the whole, tissue, and cellular levels. Taking βARK1, β-arrestin-1 and β-arrestin-2 as the key observational indicators, we have provided a new target for clinical treatment of SIMD, providing a new theoretical basis for esmolol to improve SIMD, and providing theoretical support for clinical reduction of sepsis mortality and improvement of prognosis. All of these have not been or only rarely been previously studied.\u003c/p\u003e \u003cp\u003eOf course, there are still many deficiencies in this study. For example, the literature selected in this study is limited, and the data on the relationship between esmolol and beta receptor pathway is relatively insufficient. The theoretical aspect is not yet systematic and mature, it is still in the preliminary research stage. The experimental scheme is not perfect, and the sample size is limited. We also fail to face the above research from the genetic level. These defects will become our future research direction.\u003c/p\u003e "},{"header":"Conclusion","content":" \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eIn summary, sepsis is a very complex pathophysiological process. Esmolol, as a kind of beta blocker, plays a huge role in the improvement of heart function during sepsis. The mechanism may be related to the fact that esmolol blocks the pathological signaling pathway induced by over-activation of beta receptors in sepsis. At the same time, it also preserves the physiological signaling pathway mediated by the beta-arrestin pathway, as well as improves the inflammatory response of myocardial cells and plays a role in the protection of the myocardial cells from multiple aspects. In the future, we should continue to explore the specific mechanism, providing new targets for the treatment of sepsis and new ideas for the better application of esmolol in clinical practice\u003c/span\u003e.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowlegements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Project fund of the Lanzhou University of Second Hospital(NO.CY-2018-MS03).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1)Affiliations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDepartment of Critical Care Medicine, Lanzhou University Second Hospital,No. 82, Cuiyingmen,Chengguan District, Lanzhou City, Gansu Province , China:\u003c/p\u003e\n\u003cp\u003ePan Li,Jing-zhuo Liu,Xin-tong Zhang,Ling-ling Zhen,Ying- zhen Wang,Xiao-rong Dong,Bei Zhang\u003c/p\u003e\n\u003cp\u003eSun Yat-sen University Zhongshan School of Medicine No.74 Zhongshan 2nd Road, Guangzhou, China:\u003c/p\u003e\n\u003cp\u003eShu-hang Luo\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2)Contributions \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePL, JZL and XTZ participated in data analysis and manuscript drafting, and LLZ contributed to the experimental design, YZW and XRD participated in animal modeling process and specimen acquisition, BZ and SHL participated in specimen detection and data processing. LM participated in manuscript revision for critical intellectual content, and the observation of the whole research process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding Author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLi Ma, MD PhD, E-mail: \u003ca href=\"mailto:[email protected],\"\[email protected],\u003c/a\u003eDepartment of Critical Care Medicine, Lanzhou University Second Hospital,No. 82, Cuiyingmen,Chengguan District, Lanzhou City, Gansu Province , China.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe experiment was approved by the Experimental Animal Ethics Committee of the Second Affiliated Hospital of Lanzhou University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSinger M, Deutschman C S, Seymour C W, et al. 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The American journal of emergency medicine, 2018, 36(3): 470-474.\u003c/li\u003e\n\u003cli\u003eXinqiang L, Weiping H, Miaoyun W, et al. Esmolol improves clinical outcome and tissue oxygen metabolism in patients with septic shock through controlling heart rate[J]. Zhonghua wei zhong bing ji jiu yi xue, 2015, 27(9): 759-763.\u003c/li\u003e\n\u003cli\u003eXinqiang L, Weiping H, Miaoyun W, et al. Esmolol improves clinical outcome and tissue oxygen metabolism in patients with septic shock through controlling heart rate[J]. Zhonghua wei zhong bing ji jiu yi xue, 2015, 27(9): 759-763.\u003c/li\u003e\n\u003cli\u003ePhilip J L, Xu X, Han M, et al. Regulation of cardiac fibroblast-mediated maladaptive ventricular remodeling by \u0026beta;-arrestins[J]. PloS one, 2019, 14(7).\u003c/li\u003e\n\u003cli\u003eSchlegel P, Reinkober J, Meinhardt E, et al. G protein-coupled receptor kinase 2 promotes cardiac hypertrophy[J]. PloS one, 2017, 12(7): e0182110.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Sepsis; Myocardial dysfunction, Esmolol; β-adrenergic signaling pathway; Receptor desensitization","lastPublishedDoi":"10.21203/rs.3.rs-16199/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-16199/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground Cardiac dysfunction caused by sepsis is a serious challenge for ICU doctors. Previous studies showed that the beta adrenergic receptor (β- AR) signaling pathway system can cause abnormal heart function. Studies have also shown that esmolol, a type of beta blocker, participates in the beta receptor desensitization that occurs. This study intends to further explore the specific mechanism of esmolol in the protection of cardiac function.\u003c/p\u003e\u003cp\u003eMethod In this study, rats were randomly divided into three groups: Sham (sham operation group), CLP (cecal ligations and function group) and ES (esmolol group). The three groups were divided into two subgroups: A and B. Group A was used to observe the number of survival days. Group B was divided into 6 hours,12 hours and 24 hours according to the time after the operation to take samples, and the rats were sacrificed after the corresponding intervention. The inflammatory factors and the factor of β receptor pathway were measured by different methods. And the hypothesis was verified by statistical methods.\u003c/p\u003e\u003cp\u003eResults ELISA tests demonstrated that the levels of inflammatory factors CA,TNF-α, and IL-6, as well as G protein pathway factors AC, CAMP and PKA in the CLP group were significantly higher than those in the Sham group, while those factors in the ES group were significantly lower than those in the CLP group, cardiac function factor cTnI is the opposite. Western blotting showed that, compared with the CLP group, the inflammatory proteins MYD88 and NF-KB in the myocardial tissue of the ES group were significantly decreased, while the levels of the beta receptor pathway proteins β1-AR, β2-AR, β-arrestin-1 and β-arrestin-2 were significantly increased, and the result of β-ARK was the opposite. Pathological results and immunofluorescence results indicated that the degree of myocardial cell injury in the ES group was significantly improved compared with that in the CLP group.\u003c/p\u003e\u003cp\u003eConclusion Esmolol has a protective effect on the heart by selectively preventing the pathologic signaling pathway mediated by overactivation of beta receptors while retaining the normal signaling pathway.\u003c/p\u003e","manuscriptTitle":"An exploration of the protective mechanism of esmolol on the heart of septic rats based on the beta-adrenergic signaling pathway.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2020-03-05 20:40:40","doi":"10.21203/rs.3.rs-16199/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fdd9069d-9f14-4ee4-bbb9-f68631d9c3d2","owner":[],"postedDate":"March 5th, 2020","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":66784,"name":"Critical Care \u0026 Emergency Medicine"}],"tags":[],"updatedAt":"2020-05-07T12:10:44+00:00","versionOfRecord":[],"versionCreatedAt":"2020-03-05 20:40:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-16199","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-16199","identity":"rs-16199","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}