Biochemical Studies on the Protective Effect of Betaine on Mitochondrial Function in Experimentally Induced Myocardial Infarction in Rats

Abstract

The present study was designed to examine the cardioprotective effect of betaine on mitochondrial function in isoprenaline-induced myocardial infarction in rats with respect to changes in the mitochondrial energy status and antioxidant defense system. Prior oral treatment with betaine significantly prevented the isoprenaline-induced elevation in the levels of diagnostic maker enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)] and homocysteine in plasma of the experimental group of rats. Its administration significantly counteracted the isoprenaline-induced aberrations in the myocardial energy status by maintaining the levels of myocardial ATP and betaine contents and the activities of mitochondrial TCA cycle enzymes [isocitrate dehydrogenase (ICDH), α-ketoglutarate dehydrogenase (α-KDH), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH)] and respiratory marker enzymes (NADH dehydrogenase and cytochrome-c-oxidase) at near normalcy. It also exerted an antioxidant effect against isoprenalineinduced myocardial infarction by blocking the induction of mitochondrial lipid peroxidation (LPO). A tendency to minimize the isoprenaline-induced alterations in the level of reduced glutathione (GSH) and in the activities of glutathione-dependent antioxidant enzymes [glutathione peroxidase (GPx) and glutathione-S-transferase (GST)] and antiperoxidative enzymes [superoxide dismutase (SOD) and catalase (CAT)] in the heart mitochondria was also observed. The results of the present study indicate that the overall cardioprotective effect of betaine is probabl yr elated to its ability to maintain the myocardial energy status (ATP) at higher level by maintaining the activities of TCA cycle enzymes and respiratory marker enzymes at near normalcy, and/or to its free radical-scavenging ability against isoprenaline-induced lipid peroxidation, which is primarily responsible for the irreversible necrosis of the myocardial membrane.