Cardiovascular effects of intravenous and intracoronary administration of atrial natriuretic peptide in halothane anesthetized dogs

Cardiovascular actions of synthetic 1-28 human natriuretic peptides (hANP) were examined in dogs anesthetized with halothane. In seven closed-chest dogs a Swan-Ganz catheter was inserted for measurement of cardiac output. Intravenous infusion of increasing doses of hANP (0.1, 0.3, 0.9ug/kg/min) lowered mena aortic pressure without affecting heart rate significantly. Cardiac output and pulmonary wedge pressure were markedly decreased while total peripheral resistance was increased significantly. All these parameters returned to control levels after 1hr of recovery with an 100-150ml of saline infusion to increase pulmonary capillary wedge pressure to the pre-infusion value. Intracoronary infusion of hANP (0.05 and 0.1ug/kg/min) did not cause any significant changes in coronary flow and regional contraction. These results indicate that the hypotensive action of hANP is due to a decrease in cardiac output mediated by reduced preload but not by negative inotropic action.