Effect of L-carnitine on cardiac hemodynamics.

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. Coronary venous blood was introduced to the extracorporeal circuit through a polyethylene catheter wedged into the coronary sinus under fluoroscopic control and was returned to the animal through the jugular vein. L-carnitine was infused intravenously at a constant rate of 80 mg/Kg/min for 8 min. Hemodynamic responses appeared within 1 to 3 min of carnitine infusion and peak effects were observed nearly after 5 min. Peak effects on cardiac hemodynamics after 5 to 8 min of carnitine infusion were as follows. Heart rate decreased by 17% from control (p less than 0.05). Aortic and left ventricular pressure increased by 20% (p less than 0.05 and p less than 0.01 respectively) and peak positive left ventricular dp/dt increased by 35% (p less than 0.01), the mean rate pressure product as the index of myocardial oxygen consumption remained unchanged. Coronary blood flow increased by 60% (p less than 0.01) and coronary vascular resistance decreased by 25% (p less than 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.