Cardiovascular effects of chronic reserpine administration in mongrel dogs

Abstract

Twenty-four mongrel dogs received small oral doses of reserpine daily for 12–13 months. Chronic administration of low doses of reserpine did not induce significant alterations in arterial blood pressures; however, there was a gradual, significant decrease in heart rate. Studies on autonomic function revealed a certain degree of impairment of cardiovascular reflexes and sympathetic tone. Hypotensive response to hexamethonium was inhibited in reserpine-treated dogs. At the termination of the study, left ventricular work was significantly lower and cardiac output decreased in the reserpine-treated group under pentobarbital anesthesia. Although the right ventricular contractile force and rate of tension development were significantly greater in the reserpine-treated group, the stroke volumes were not. Greater pressor responses obtained to intravenous administration of epinephrine and norepinephrine in the reserpine group were due to a greater elevation of total peripheral resistance rather than cardiac output. It is concluded that the efficiency of the right ventricular myocardium was attenuated in the dogs treated with reserpine.