Effects of L-carnitine on phospholipids in the ischemic myocardium

To evaluate the protective effects of L-carnitine on the ischemic myocardium, the effects of its administration on tissue levels of high energy phosphate and phospholipids were studied in ischemic dog hearts. Myocardial ischemia was induced by the ligation of the left anterior descending coronary artery for 40 min. In the experiment, L-carnitine (300 mg/kg) was administered intravenously prior to coronary artery ligation. Mitochondrial phospholipids were extracted from nonischemic and ischemic regions of the myocardium and subsequently analyzed. In ischemic myocardial tissues, levels of adenosine 5'-triphosphate (ATP) were reduced. The decrease was significantly elevated by L-carnitine pretreatment. The mitochondrial fractions obtained from ischemic myocardia had significantly lower levels of phospholipids than those obtained from nonischemic tissues. Moreover, the amounts of phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine were significantly decreased in ischemic myocardial tissues. L-carnitine-pretreatment prevented the reduction of these phospholipids. Lysophosphatidylethanolamine and sphingomyelin did not show statistically significant decreases. This may explain why the administration of carnitine has beneficial effects on ischemic myocardium.