Exercise training improves early survival rate in diabetic rats submitted to acute coronary artery ligation

This study was designed to test the hypothesis that the decreased early survival rate of diabetic rats submitted to acute experimental myocardial infarction could be improved by a previous training program. Male Wistar rats (+/- 200 g) were rendered diabetic with the i.v. injection of streptozotocin (45 mg/kg) but only those presenting one week later a tail-blood glucose value between 250-400 mg/dl were retained in the protocol. Diabetic and control rats were either kept sedentary or submitted to a progressive 10-week program of treadmill running. The left coronary artery was then ligated under ether anesthesia. Adequate occlusion was confirmed by an elevation of plasma CK-MB levels four hours later or by a toluidine blue injection technique in rats which died earlier. Since the first 20 minutes after such a procedure represents a most critical period for sudden death, the early survival rate was calculated for each group of rats and significance in differences was established with the Fisher's test. While the 27% early survival rate observed in sedentary diabetics was significantly lower (p = 0.02) than the 49% found in sedentary controls, this was completely alleviated by previous training in diabetic animals (50%; p = 0.018 vs sedentary diabetics and 0.623 vs sedentary controls). This beneficial effect of training was not found in nondiabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)