Effects of L-carnitine on ventricular arrhythmias in dogs with acute myocardial ischemia and a supplement of excess free fatty acids.

Abstract

The effects of L-carnitine on ventricular arrhythmias were evaluated in dogs with acute myocardial ischemia and a supplement of excess free fatty acids (FFA). Acute myocardial ischemia was induced by ligation of left anterior descending coronary artery. After 80 min of coronary occlusion, high plasma FFA was induced by i.v. injection of heparin 200 u/kg and Intralipid 5 ml/kg as a bolus. After additional 60 min, bearing hearts were removed from animals and tissue levels of free carnitine, short and long chain acyl carnitine, FFA and ATP were determined. L-Carnitine 100 mg/kg was administered i.v. 5 min before coronary artery ligation. ECG were recorded continuously by a Holter ECG recorder during the experiment and ventricular arrhythmias were quantified by an arbitrary scoring system. In ischemic and excess FFA supplemented myocardium, free carnitine and ATP decreased, whereas long chain acyl carnitine and FFA increased. And these metabolic changes tended to be reduced by L-carnitine. Pretreatment of L-carnitine reduced the grade of ventricular arrhythmias induced both by acute myocardial ischemia and by supplement of excess FFA. The administration of L-carnitine may be beneficial to prevent serious arrhythmias in ischemic heart disease, presumably by restoring the impaired FFA oxidation.