EFFECTS OF ACETYL STROPHANTHIDIN ON CARDIOVASCULAR FUNCTION IN INTACT, CONSCIOUS DOGS

¹ Thorndike Memorial Laboratory, Harvard Medical Unit, Boston City Hospital and the Department of Medicine, Harvard Medical School, Boston, Massachusetts

Eight intact, conscious mongrel dogs were studied to investigate the hemodynamic effects of and tolerance to acetyl strophanthidin and the data were compared with those from anesthetized dogs described in the literature. The study was done under light sedation with morphine sulfate, 15 mg. Acetyl strophanthidin was given i.v. by continuous infusion at 3 µg/kg/min until ventricular tachycardia was noted. It was found that in conscious animals, acetyl strophanthidin did not significantly alter heart rate, aortic, pulmonary arterial or left ventricular end-diastolic pressures or systemic or pulmonary vascular resistance. Stroke volume, systolic ejection rate and stroke power increased significantly. These results contrast strikingly with the rise in peripheral vascular resistance and decrease in cardiac output which is noted in anesthetized dogs. The results suggest that the more competent barostatic mechanism in the unanesthetized state may produce an entirely different hemodynamic response to systemic digitalization compared to the anesthetized state.