Effect of L-Carnitine on Cardiac Hernodynamics

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The effect of L-carnitine on cardiac hemodynamics was evaluated in normal closed chest dogs. Extracorporeal circulation was produced to measure coronary blood flow in closed chest dogs. Coronay venous blood was introduced to the extracorporeal circuit through a polyethylene catheter wedged into the coronay sinus under fluoroscopic control and was returned to the animal through the left jugular vein. L-carnitine was infused intravenously at a constant rate of 80mg/Kg/min for 8min. Hemodynamic responses appeared within 1 to 3min of carnitine infusion and peak effects were observed nearly after 5min. Peak effects on cardiac hemodynamics after 5 to 8min of carnitine infusion were as follows. Heart rate decreased by 17% from control (p<0.05). Aortic and left ventricular pressure increased by 20% (p<0.05 and p<0.01 respectively) and peak positive left ventricular dp/dt increased by 35% (p<0.01), the mean rate pressure product as the index of myocardial oxygen consumption remained unchanged. Coronary blood flow increased by 60% (p<0.001) and coronary vascular resistance decreased by 25% (p<0.01). As the infusion of carnitine was discontinued, the effects promptly disappeared. These data suggest that L-carnitine has direct vasodilating and positive inotropic effects on cardiovascular system.