The effects of L-carnitine on ischemic and reperfusion arrhythmias in isolated rat hearts

Abstract

Isolated rat hearts were subjected to 30 min coronary artery occlusion followed by 120 min reperfusion. Hearts (n = 8-12) were perfused with L-camitine (0.5-5 mM) for 10 min pre- and post-ischemia or reperfusion and for the whole period of ischemia and reperfusion. Perfusion of carnitine during ischemia/reperfusion produced a marked (p < 0.05) and dose dependent reduction in the total number of VT (max 65%) during reperfusion. The incidence of reperfusion VF was also decreased from its control value of 63% to 17%. in hearts perfused with 5 mM of carnitine, as reflected by a significant (p < 0.05) decline of VF duration from 218 +/- 99 sec in control to 19 +/- 19 sec. Perfusion of etomoxir but not ranolozine along with carnitine reversed the anti-arrhythmogenic action of the drug. Short time, pre ischemic administration of carnitine had dose dependent arrhythmogenic effects both on ischemia and reperfusion induced arrhythmias. These results show that L-carnitine produced a protective effect against reperfusion arrhythmias only when it was perfused for the whole period of the experiment. This protective action was reversed by concomitant use of etomoxir but not ranolozine, suggesting that the efficacy of carnitine was due to its mitochondrial action but was not solely attribute to an increase in fatty acid oxidation.