Partial correction of impaired creatine kinase activity in diabetic rat heart by physical training

The effect of physical training on total creatine kinase (CK), CK-MM, and CK-MB isoenzyme activity was studied in hearts of diabetic and control rats. Diabetes was induced with streptozotocin (50 mg/kg), and only rats with blood glucose levels between 14 and 22 mmol/L 1 week later were kept in the protocol. Exercise training was performed on a treadmill in a progressive 10-week program. Physical training did not induce any significant changes in plasma glucose or insulin levels in diabetic rats. Total CK, CK-MM, and CK-MB activity was decreased in diabetic rat heart by 27%, 22%, and 56%, respectively. Physical training did not induce any important changes in CK activity in heart of nondiabetic rats. However, in diabetic rat heart, training increased total CK activity by 13%, CK-MM activity by 12%, and CK-MB activity by 31%. We conclude that the decrease in cardiac CK activity observed in chronic experimental diabetes mellitus can be partly alleviated by a program of physical training. This may be one of the mechanisms whereby physical conditioning improves cardiac function in experimental diabetes.