DOBUTAMINE POTENTIATES AMRINONES BENEFICIAL-EFFECTS IN MODERATE BUT NOT IN ADVANCED HEART-FAILURE - P-31-MRS IN ISOLATED HAMSTER HEARTS

There is controversy as to whether potent inotropic agents are beneficial or detrimental in moderate to severe heart failure. Accordingly, we studied the effects of amrinone, amrinone plus dobutamine, and dobutamine alone on mechanical performance, myocardial oxygen consumption, and high energy phosphate metabolism in different stages of congestive heart failure in the cardiomyopathic Syrian hamster. In hearts with moderate heart failure, administration of amrinone, amrinone plus dobutamine, and dobutamine alone increased developed pressure significantly, whereas the phosphorylation potential increased significantly only with amrinone and amrinone plus dobutamine. In hearts with advanced heart failure, administration of amrinone and amrinone plus dobutamine increased developed pressure significantly, whereas dobutamine alone had no effect. The phosphorylation potential improved significantly only with amrinone. Thus, amrinone improved mechanical performance and mitochondrial activity in both heart failure states. Dobutamine potentiated amrinone's beneficial effects in moderate heart failure, but negated the positive inotropic effect of amrinone in advanced heart failure. Therefore, hearts responded differently to potent inotropic agents dependeing on the severity of heart failure.