Beyond Intensity Imaging: Dissipative Equilibrium of NADH/NAD⁺ as a Metabolic Sensor for Ischemic Response in Cardiac Tissue

Beyond Intensity Imaging: Dissipative Equilibrium of NADH/NAD⁺ as a Metabolic Sensor for Ischemic Response in Cardiac Tissue | 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 Article Beyond Intensity Imaging: Dissipative Equilibrium of NADH/NAD⁺ as a Metabolic Sensor for Ischemic Response in Cardiac Tissue Valeriya Tsvelaya, Mikhail Slotvitsky, Mikhail Medvedev, Georgii Pashintsev, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7159262/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 The conversion of nicotinamide adenine dinucleotide (NAD⁺) to its reduced form (NADH) by dehydrogenases is a key step in numerous redox reactions and, consequently, in cellular energy conversion. NADH autofluorescence imaging represents a promising method for the optical detection of metabolic dysfunction in living tissues. However, it is sensitive to the total NAD(H) content as well as to variations in absorption and light scattering, which may fluctuate independently. A major objective is therefore to identify invariant quantities that are responsive to reversible ischemic tissue injury while circumventing the limitations of intensity-based imaging. We show experimentally and in silico that glutamate dehydrogenase drives the NAD⁺/NADH balance toward a dissipative equilibrium when an external catalytic process promotes the NADH → NAD⁺ conversion. This dissipative equilibrium state is uniquely determined by the total NAD(H) pool, the GDH concentration, and the external catalytic activity. Experimental validation using UV-induced NADH photolysis (300–500 mW/cm²) implementing the NADH → NAD⁺ reaction showed that GDH activity can be estimated in the epicardium of ex vivo Langendorff-perfused hearts by analyzing the dissipative equilibrium. These results present a new approach to optical assessment of tissue metabolic activity based on autofluorescence imaging of NADH. Our method allows assessment of cardiac tissue ischemia without knowledge of the photolysis rate, thereby overcoming the inherent limitations of optical detection in living tissues. Biological sciences/Biophysics Health sciences/Cardiology/Cardiovascular biology/Cardiovascular diseases Physical sciences/Optics and photonics/Optical techniques/Imaging and sensing NADH imaging metabolic sensor ischemia mapping photolysis heart perfusion dissipative equilibrium cardiac tissue Full Text Additional Declarations There is NO Competing Interest. Supplementary Files supplementaryNADH.docx Supplementary Figures 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-7159262","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":488376096,"identity":"ecd21e59-f7e9-4449-891a-4c0ce2871e0e","order_by":0,"name":"Valeriya Tsvelaya","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvUlEQVRIiWNgGAWjYHACxocfKkB0ArEa2BiYjSXOkKiFTYK3jRQtBvfbn0lIzjssb86efEyCcc9hIrQc4zG2KNx22HBnz7NkA4ZnRGiRbONhvCG57TDjhhs5hg8YDhClhf2BBO+cw/YbbuR/OECUFn42BiMJ3obDiUBbGImzhZ8tx9hY4lh68oYzz4wNEg6kE9bCxnz84cMPNda2G44nP5P4cMCasBYoaIZQCURrYGCoI0HtKBgFo2AUjDgAALyJPEyyQnmeAAAAAElFTkSuQmCC","orcid":"","institution":"Moscow Center for Advanced Studies","correspondingAuthor":true,"prefix":"","firstName":"Valeriya","middleName":"","lastName":"Tsvelaya","suffix":""},{"id":488376097,"identity":"b70df674-be09-4685-97fe-11e2cdb975cc","order_by":1,"name":"Mikhail Slotvitsky","email":"","orcid":"","institution":"ITMO","correspondingAuthor":false,"prefix":"","firstName":"Mikhail","middleName":"","lastName":"Slotvitsky","suffix":""},{"id":488376098,"identity":"2edcd743-32fe-4570-8a13-80901cfe3e42","order_by":2,"name":"Mikhail Medvedev","email":"","orcid":"https://orcid.org/0009-0004-8932-9773","institution":"ITMO","correspondingAuthor":false,"prefix":"","firstName":"Mikhail","middleName":"","lastName":"Medvedev","suffix":""},{"id":488376099,"identity":"b05ce25d-8d84-407b-a669-55190347fcf1","order_by":3,"name":"Georgii Pashintsev","email":"","orcid":"https://orcid.org/0009-0004-3377-1618","institution":"ITMO","correspondingAuthor":false,"prefix":"","firstName":"Georgii","middleName":"","lastName":"Pashintsev","suffix":""},{"id":488376100,"identity":"248b958a-a114-4f54-9f80-6aff94d300a8","order_by":4,"name":"Valeryia Kachan","email":"","orcid":"https://orcid.org/0009-0004-1599-6119","institution":"ITMO","correspondingAuthor":false,"prefix":"","firstName":"Valeryia","middleName":"","lastName":"Kachan","suffix":""},{"id":488376101,"identity":"9b94e5bb-89ed-4637-982d-775fafda0836","order_by":5,"name":"Romanova Serafima","email":"","orcid":"","institution":"Moscow Center for Advanced Studies","correspondingAuthor":false,"prefix":"","firstName":"Romanova","middleName":"","lastName":"Serafima","suffix":""},{"id":488376102,"identity":"909fa136-1062-4110-8a93-7ce1ae71150b","order_by":6,"name":"Konstantin Agladze","email":"","orcid":"","institution":"M. 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NADH autofluorescence imaging represents a promising method for the optical detection of metabolic dysfunction in living tissues. However, it is sensitive to the total NAD(H) content as well as to variations in absorption and light scattering, which may fluctuate independently. A major objective is therefore to identify invariant quantities that are responsive to reversible ischemic tissue injury while circumventing the limitations of intensity-based imaging. We show experimentally and in silico that glutamate dehydrogenase drives the NAD⁺/NADH balance toward a dissipative equilibrium when an external catalytic process promotes the NADH → NAD⁺ conversion. This dissipative equilibrium state is uniquely determined by the total NAD(H) pool, the GDH concentration, and the external catalytic activity. 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