EFFECTS OF L-CARNITINE ON TISSUE LEVELS OF ACYL CARNITINE, ACYL COENZYME A AND HIGH ENERGY PHOSPHATE IN ISCHEMIC DOG HEARTS

In order to evaluate the protective effects of L-carnitine on ischemic myocardium, its effects on tissue levels of acyl carnitine, acyl coenzyme A (CoA) and high energy phosphate were studied in ischemic dog hearts. Myocardial ischemia was induced by the ligation of left anterior descending coronary artery for 15 minutes. L-carnitine ( 100 mg/kg) was administered intravenously prior to coronary ligation. In ischemic myocardium, tissue levels of free carnitine decreased from 1043 ± 358 to 623 ± 180 n mol/g (p<0.001). On the other hand, long chain acyl carnitine increased from 214 ± 54 to 498 ± 149 n mol/g (p<0.001) and long chain acyl CoA increased from 15.7 ± 4.8 to 23.2 ± 5.4 n mol/g (p<0.01 ). Pretreatment of L-carnitine increased tissue levels of free carnitine to 863 ± 318 n mol/g (p<0.005) and decreased long chain acyl carnitine and long chain acyl CoA to 368 ±128 n mol/g (p<0.02) and 19.2 ± 6.5 n mol/g (p<0.1) respectively. Tissue levels of adenosine triphosphate (ATP) that was reduced by myocardial ischemia from 5.43± 0.67 to 2.80 ± 0.58 μ mol/g (p<0.001) was increased to 3.28 ± 0.63 μ mol/g (p< 0.02) by L-carnitine. Positive correlation was observed between ATP and free carnitine (p<0.01). On the other hand, negative correlation was observed not only between ATP and the ratio of long chain acyl CoA to free carnitine but also between ATP and the ratio of long chain acyl carnitine to free carnitine (p