The cardioprotective effects of a combination of quercetin and α-tocopherol on isoproterenol-induced myocardial infarcted rats

Abstract The present study aims to evaluate the combined protective effects of quercetin and α‐tocopherol on isoproterenol‐treated myocardial infarcted rats. Male albino Wistar rats were pretreated with a combination of quercetin (10 mg/kg) and α‐tocopherol (10 mg/kg) daily for 14 days. After the pretreatment, rats were injected isoproterenol (100 mg/kg) to induce myocardial infarction. Isoproterenol‐treated rats showed increased levels of serum troponins and increased intensities of serum lactate dehydrogenase‐1 and ‐2 isoenzyme bands. Isoproterenol treatment also showed significant decreased levels of antioxidant system and significant increased levels of plasma lipid peroxidation, plasma uric acid, and the heart calcium. Furthermore, isoproterenol‐treated rat's electrocardiogram showed elevated ST segments. Combined pretreatment with quercetin and α‐tocopherol normalized all the biochemical parameters and minimized the alterations in electrocardiogram. Histopathology of myocardium also confirmed the cardioprotective effects of quercetin and α‐tocopherol. In vitro studies confirmed the mechanism of action of quercetin and α‐tocopherol. Thus, quercetin and α‐tocopherol exhibited cardioprotective effects against isoproterenol‐induced cardiotoxicity due to their scavenging free radicals, improving antioxidants and maintaining Ca 2+ levels. Our study also showed that combined pretreatment (quercetin and α‐tocopherol) was highly effective than single pretreatment (quercetin or α‐tocopherol). © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 25:28–40 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.20357