Influence of the diabetic state on isoproterenol-induced cardiac necrosis.

Isoproterenol-induced myocardial necrosis was examined in male mice with alloxan-induced and genetically transmitted diabetes. Ten days after alloxan treatment, mice exhibited an elevation in blood glucose concentrations, weight loss, polyuria and decreased heart rates (510 +/- 15 v. 675 +/- 11 beats/min) compared with matched control mice. Similarly, genetically diabetic mice exhibited lower heart rates than the corresponding age-matched controls (383 +/- 30 v. 603 +/- 30 beats/min). In comparison to matched controls, both groups of diabetic mice had a significant decrease in the severity of the cardiac necrosis which was induced by the administration of isoproterenol. The reduction in isoproterenol-induced cardiac lesions was similar in mice with chemically induced diabetics and mice with genetically transmitted diabetes. Biochemical studies of ventricular slices revealed no change in basal cAMP levels and no differences in isoproterenol-induced changes in cAMP levels in mouse hearts from both models of diabetes. Insulin treatment corrected the chemically induced diabetic state and restored the cardiotoxic potential of isoproterenol.