Effects of in vivo and in vitro treatment with L-carnitine on isolated hearts from chronically diabetic rats

The effects of in vivo and in vitro L-carnitine administration on cardiac function were studied in isolated perfused working hearts from control and diabetic rats. Injection of L-carnitine (3 g.kg-1.day-1, i.p.) for 2 weeks into rats previously diabetic for 6 weeks partially reversed the adverse effects of chronic diabetes on heart function. In a second experiment, a lower dose of L-carnitine (0.5 g.kg-1.day-1, i.p.) injected for 6 weeks prevented the onset of heart dysfunction in chronically diabetic rats. The protective action of L-carnitine in the myocardium appeared to be independent of any direct pharmacological effects. In both studies, L-carnitine was a potent lipid-lowering agent. The data suggests that L-carnitine administration at either dose had a protective effect against myocardial damage seen during diabetes. The mechanism(s) underlying these effects remains to be elucidated but are discussed.