Improvement of pentobarbital-induced heart failure by MCI-154, a novel and potent cardiotonic agent, in the dog heart-lung preparation.

The efficacy of MCI-154, a new pyridazinone cardiotonic agent, in improving heart failure was assessed in dog heart-lung preparations in which cardiac function had been severely depressed by pentobarbital. MCI-154 in doses of 10-100 micrograms improved the cardiac function curve and restored it to the control level at 100 micrograms. At this dose, MCI-154 neither produced an increase in heart rate beyond the control value nor induced arrhythmias. The effects of MCI-154 were not affected by atenolol, a cardioselective beta 1-blocker. These results indicate that MCI-154 would be of potential use in the treatment of heart failure.