Myocardial and hepatic free carnitine concentrations in pups of diabetic female rats.

Background/aims: Adequate carnitine levels are required for normal fatty acid and energy metabolism in heart muscle. It is well known that streptozotocin-induced diabetic rats develop myocardial carnitine deficiency and that carnitine therapy may be beneficial to the diabetic heart. Infants of diabetic mothers (IDM) are known to be at risk for developing a hypertrophic type of cardiomyopathy. In the present investigation, we examined the free carnitine concentration from cardiac and hepatic tissue in pups of streptozotocin-induced diabetic female rats. We also assessed the effect of maternal L-carnitine supplementation on the free carnitine concentration in pups of diabetic rats.

Method: Three groups, each consisting of 4 Wistar albino female rats, were studied, Group 1 (untreated diabetic; n = 4) and group 2 (L-carnitine-treated diabetic; n = 4) rats were given streptozotocin (60 mg/kg) by intraperitoneal injection; group 3 were controls. During pregnancy, L-carnitine was given at a dose of 150 mg/kg by intraperitoneal injection once a day for 14 days. Cesarean section was carried out, and 113 newborn rats (group 1 n = 36; group 2 n = 38; group 3 n = 39) were obtained from all the pregnant rats.

Results: The free carnitine concentration in myocardial tissue was significantly decreased in the female diabetic rats (p < 0.001). However, the free carnitine concentration from hepatic tissue in diabetic female rats was similar to that in controls. In pups of group 1 diabetic rats, a significantly decreased free carnitine concentration was found in both myocardial and hepatic tissue compared to group 2 and controls. The free carnitine content from myocardial and hepatic tissue was significantly elevated in the maternal L-carnitine-supplemented group when compared to group 1 and control pups (p < 0.001 and p < 0.05, respectively).

Conclusions: The present study has demonstrated that the free carnitine concentration from myocardial and hepatic tissue is significantly reduced in pups of streptozotocin-induced diabetic female rats. This study has also shown that administration of maternal L-carnitine improves the carnitine level in pups of diabetic rats. A decreased myocardial carnitine concentration may be partly responsible for the development of cardiomyopathy in IDM.