L-CARNITINE EFFECTS ON THE STUNNED MYOCARDIUM REGIONAL FUNCTION DUE TO VERY BRIEF ISCHEMIAS

Introduction and objectives. Myocardial ATP is produced mainly by fatt y acid oxidation, a process in which the fatty acid metabolite carrier carnitine is needed to carry the metabolites into the mitochondria. C ardiac ischemia is associated with carnitine depletion. Our objective was to study the functional effect of L-carnitine on myocardium stunne d by very brief, repeated ischemias, and to examine its actions in the recovery period. Methods. The two series studied were the control ser ies (7 dogs) and the carnitine series (7 dogs). L-carnitine was admini stered to the carnitine series at doses of 250 mg/kg/day starting 7 da ys before the ischemic protocol and continuing during the follow-up pe riod (10 and 15 days). The ischemic protocol consisted of 20 anterior descending coronary artery occlusions lasting 2 min and with 3 min of reperfusion between occlusions. Global and regional cardiac function p arameters were recorded daily. Results. No differences in the global f unctional (haemodynamic) or ECG of the two series were found, but ther e were differences in regional myocardial function. The control series segment shortening fraction fell to dyskinesis values during the occl usion periods, then recovered during reperfusions. The segment shorten ing fraction worsened during the stunning period, reaching its maximal impairment on the 5th day, after which it returned to basal values on the 15th day. The carnitine series showed the same performance in the occlusion/reperfusion period. However, during the stunning period the segment shortening fraction recovered and reached values close to the basal ones maintained them during the follow-up period. Conclusions. L-carnitine induces an almost immediate recovery of myocardial contrac tility, when it has been affected by very brief, repeated coronary occ lusions. It limits the myocardial stunning apparition.