Cooling of cultured water can resist heart failure caused by collagen deposition and necrosis of cardiac fibers under chronic heat stress in sturgeon

Abstract Background Chronic heat stress (CHS) may threaten the survival of cultivated and wild sturgeon by jeopardizing heart function. Methods Therefore, we established a heart damage model for the Siberian sturgeon (Acipenser baerii) using varying degrees of CHS (24°C and 28°C) to explore its effect on the heart structure and function, and their mutual relationship. Results Our research showed that CHS caused systemic heart failure in A. baerii, clinically manifested as severely irregular ventricles, increased myocardial fibrotic in the interstitium of cardiomyocytes, and myocardial necrosis. Echocardiographic imaging of A. baerii revealed an accelerated heart rate, incomplete ventricular contraction, decreased cardiac output, and significantly reduced pumping efficiency under CHS. Generally, the contractility of the heart decreased and the afterload increased under CHS, which is typical of high-resistance and low-output heart failure. However, cooling of cultured water (20°C) can offset the adverse effects of partial or total CHS on tissue structure and function. Conclusion Our results systematically characterized the relationship between the effects of CHS on the heart structure and heart function in sturgeon. This work provides a preliminary reference for future summer breeding pond management and protection of sturgeon.