Diabetic cardiomyopathy and carnitine deficiency

This study was designed to study the pathogenesis of cardiomyopathy in anim als with longstanding (6 months) diabetes mellitus. Male Wistar rats were m ade diabetic by the injection of streptozotocin (35 mg/kg) intraperitoneal at 6 months of age, Myocardial contractility was evaluated at 1 year of age by an echocardiogram. Blood was collected at that time to measure blood gl ucose and hemoglobin A(1c) as an indicator of metabolic control. Serum carn itine was also measured on the same sample to evaluate the availability of this substance so essential for fatty acid metabolism in the myocardium. My ocardial anatomy was evaluated by both light and electron microscopy after the animals had diabetes for 6 months. It was found that the left ventricul ar volume was greater at the end of systole and diastole. There was the sug gestion of left ventricular fractional shortening and calculated reduced ej ection fraction indicating decreased contractility consistent with cardiomy opathy, The hearts had no evidence of coronary vascular occlusion, and the serum cholesterol was normal. Myocardial ultrastructure revealed abnormal-a ppearing mitochondria consistent with carnitine deficiency. Serum and myoca rdial carnitine levels in the animals with diabetes and reduced myocardial function were low. Carnitine levels and metabolism could be important in th e pathogenesis of diabetic cardiomyopathy. (C) 1999 Elsevier Science Inc.