ALPHA-LIPOIC ACID AND AMLODIPINE AMELIORATE MYOCARDIAL

This study was designed to examine the cardioprotective effects of alpha-lipoic acid and amlodipine against isoproterenol-induced myocardial infarction in rats. Electrocardiograph parameters were monitored, diagnostic cardiac marker enzymes and myocardial antioxidative parameters were measured. Histopathological examination of heart tissues was also performed. Subcutaneous injection of isoproterenol (85 mg/kg at 24 h intervals for 2 days) to male Wistar rats induced marked alterations in ECG-patterns, as well as significant increases in serum level of creatine phosphokinase–MB (CPK-MB), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Moreover, the level of myocardial thiobarbituric acid-reactive substances was significantly increased, while reduced glutathione content and the activities of antiperoxidative enzymes [catalase and superoxide dismutase] in heart tissue were significantly decreased. Daily pre-treatment with either alpha-lipoic acid (100 mg/kg p.o.) or amlodipine (5.0 mg/kg p.o.) for respective periods of 15 or 7 days altered almost all of the above mentioned myocardial changes induced by isoproterenol. Meanwhile, the combination of alpha-lipoic acid and amlodipine significantly reduced isoproterenol-induced elevations in diagnostic marker enzyme levels and almost restored normal ECG-patterns in experimental animals. In addition, this combination exerted a synergistic antioxidant effect by blocking the induction of lipid peroxidation. The same combination also prevented isoproterenol-induced alterations in the level of reduced glutathione and the activities of antiperoxidative enzymes. Histopathological observations were found to support these biochemical results. These findings indicate that alpha-lipoic acid and amlodipine exerted a synergistic cardioprotective effect on acute myocardial infarction induced by isoproterenol in rats