Tetrandrine Ameliorates Myocardial Ischemia-Reperfusion Injury by Preventing Mitochondrial Oxidative Damage And Restoring Mitochondrial Energy Metabolism

Introduction: Myocardial ischemia-reperfusion (I/R) injury is a common complication of cardiovascular disease that occurs when blood flow is restored to ischemic heart tissue, but paradoxically causes further tissue damage. It is a key factor that affects the treatment effect of acute myocardial infarction. Therefore, it is important to explore novel treatment strategies to improve myocardial I/R injury. Tetrandrine (TET) is a bisbenzyltetrahydroisoquinoline alkaloid derived from the medicinal herb Stephania tetrandra S Moore. This compound possesses calcium antagonistic, hypotensive, immunosuppressive, antioxidant, and anti-inflammatory properties. With its free radical scavenging and its antiadhesion and anti-inflammatory capability, TET may be of particular use as a protective agent against myocardial I/R injury. In this study we evaluated the efficacy of treatment with TET in protecting against cardiac I/R injury in perfused mouse hearts and investigated the possible mechanisms of its effect. Methods: Forty C57BL/6nj mice were randomly assigned into three groups: Normal perfusion (n = 12), Vehicle (n = 14), and TET treatment (n =14). The heart was Isolated and perfused with Krebs-Henseleit (KH) buffer in the Langendorf mode and stabilized for 30 min, followed by 10 min baseline. For Normal perfusion, the hearts were then continuously perfused with KH buffer for 170 min. For Vehicle or TET treatment, the hearts were treated with vehicle or 3 μM TET for 20 min, then subjected to global, no-flow normothermic ischemia for 30 min followed by reperfusion with KH buffer supplemented with vehicle or 3 μM TET for 120 min (30’I/120’R). Cardiac function were monitored using PowerLab continuously and myocardial high energy phosphates were determined using P31-NMR spectroscopy simaltaneously. Effluent was collected to detect the release of lactate dehydrogenase. At the end of the reperfusion, half of the hearts were stained with 2,3,5-triphenyltetrazolium chloride to evaluate infarct size, whereas the other half were freeze-clamped. The high energy phosphates ATP, ADP, and AMP and redox couples GSH/GSSG, NADH/NAD + , and NADPH/NADP + were measured in the freeze-clamped tissues using high performance liquid chromatography. In order to assess reactive oxygen species generation and oxidative damage to mitochondrial lipids and proteins, the mitochondria were isolated to determine H 2 O 2 , malondialdehyde (MDA) and protein carbonyls using Amplex Red, TBA and ELISA, respectively, respectively. Results: Compared with normal perfusion, 30’I/120’R induced significant cardiac dysfunction (evidenced by decreases in left ventricular developed pressure, rate pressure product, the maximal rate of pressure development and the maximal rate of pressure decline), energy failure (indicated by decreased ATP and energy charge), mitochondrial oxidative stress (marked by increased H 2 O 2 , MDA and protein carbonyls) and cardiomyocyte death (demonstrated by infarct tissue and increased lactate dehydrogenase). 3 μM TET treatment significantly reduced the heart infarct size and lactate dehydrogenase, and improved cardiac functional recovery after 30’I/120’R injury. Consistently, TET reversed 30’I/120’R-induced mitochondrial oxidative stress and energy failure. Conclusions: Our data indicate that TET protects the heart against myocardial I/R injury by preventing mitochondrial oxidative damage and restoring mitochondrial energy metabolism in perfused Mouse heart. TET is worthy of more investigations. This study was supported, in part, by the National Institutes of Health grants HL157367-01A1 and Brigham and Women hospital core funding grant. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.