Beneficial effect of exercise training on cardiac long-chain acylcarnitine levels in diabetic rats.

Long-chain acylcarnitines are markedly elevated in the diabetic rat heart. This could be associated with the increased rate of fatty acid metabolism in this tissue seen in the diabetic animal. The effect of exercise training on this carnitine derivative in the diabetic rat, however, has received very little attention. We therefore examined the effect of exercise training on this derivative as well as other carnitine esters in hearts of diabetic rats. Four groups of male Wistar rats were used: sedentary-control (SC), trained-control (TC), sedentary-diabetic (SD), and trained-diabetic (TD). Diabetes was induced by the I.V. injection of streptozotocin at the dose of 50 mg/kg. Training was performed on a motor-driven treadmill according to a ten-week program. 60 hr after the last bout of exercise, the rats were killed by decapitation and the hearts were quickly excised and placed in liquid nitrogen for measurement of total carnitine and its acyl derivatives. SD and TD had significantly lower levels of total (p less than 0.001) and free carnitine (p less than 0.01) compared to the respective control groups. Exercise had no effect on total and free carnitine levels in both control and diabetic groups. Short-chain acylcarnitine levels were neither altered by training nor diabetes. Heart tissue levels of long-chain acylcarnitine were increased (p less than 0.01) in SD compared to SC. However, exercise training resulted in a significant (p less than 0.05) reduction in long-chain acylcarnitines in diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)