Effect of conditioning on myocardial metabolism after myocardial infarction

The present study was conducted to evaluate the effect of prior physical training on metabolic changes after isoproternol-induced myocardial infarction in albino rats. The evaluation was done in terms of serum transaminases (SGOT and SGPT), serum lactic dehydrogenase (LDH), serum creatine phosphokinase (CPK), cardiac glycogen, and cardiac noradrenaline. Male albino rats weighed 100-150 g were selected for the study. Physical training (conditioning) consisted in making the animals swim in a tank of water for 60 min daily on 6 days a week, for 8 weeks. Myocardial infarction was produced by subcutaneous injection of isoproterenol, 85 mg/kg body weight, on 2 consecutive days. There was significantly less elevation of SGOT, LDH and CPK in the conditioned group after myocardial infarction; the rise in SGPT was not significantly different in the two groups. A smaller rise of serum enzymes revealed less myocardial damage in the conditioned group; the rise in FFA was also less in the conditioned group, a more favorable situation for an ischemic myocardium. No significant difference was observed in cardiac glycogen and cardiac noradrenaline after isoproterenol-induced cardiac necrosis. The significance of these observations is discussed.