EFFECTS OF ELTANOLONE ON MYOCARDIAL PERFORMANCE AND CORONARY FLOW IN INTACT AND CATECHOLAMINE-DEPLETED ISOLATED RABBIT HEARTS

Background Experimental studies suggest that the new short-acting intr avenous anesthetic agent eltanolone does not markedly alter hemodynami cs or cardiac function. However, because its intrinsic effects on myoc ardial performance and coronary blood flow are not yet known, they wer e examined in isolated blood-perfused rabbit hearts. Methods: Coronary blood flow, myocardial contractility, relaxation, and oxygen consumpt ion were measured during perfusion of hearts with 0.1 to 10 mu g/ml el tanolone (n = 7) or its vehicle (n = 7). To determine whether the card iac effects of eltanolone are mediated by indirect sympathetic activat ion, the same dose-response curve was studied in another group of five hearts depleted of catecholamine with reserpine treatment. Results: C oronary blood flow significantly increased with 10 mu g/ml eltanolone and significantly decreased with 10 mu g/ mi eltanolone vehicle. At el tanolone concentrations less than 10 mu g/ml, myocardial contractility and relaxation remained unchanged but decreased at 10 mu g/ml. Myocar dial contractility and relaxation mere not affected by perfusion of el tanolone vehicle alone. In eltanolone-perfused hearts, unchanged myoca rdial oxygen consumption was associated with significant increases in coronary venous oxygen content and tension, but in vehicle-perfused he arts, it was associated with reduced coronary venous oxygen content an d tension, In catecholamine-depleted hearts, the variations in myocard ial performance and coronary blood flow induced by eltanolone were sim ilar to those observed in intact hearts. Conclusions: Eltanolone (0.1 to 3 mu g/ml) did not alter myocardial performance or coronary blood f low in isolated blood-perfused rabbit hearts. These effects were not d ue to an eltanolone-induced indirect sympathetic activation, Cardiac d epression and coronary vasodilatation were only observed at concentrat ions of eltanolone far greater than those in clinical range.