RELATIONSHIP AMONG CARDIAC SYMPATHETIC-NERVE ACTIVITY, BLOOD-PRESSURE AND HEART-RATE DURING INFUSION OF CARPERITIDE IN RATS

The effect of the infusion of carperitide (alpha-human atrial natriuretic peptide; alpha-hANP) on cardiac sympathetic nerve activity, blood pressure and heart rate was studied in anesthetized rats. Intravenous infusion of carperitide (0.1 and 1.0-mu-g/kg/min) produced mild and dose-related decreases in mean arterial pressure without significant changes in cardiac sympathetic nerve activity or heart rate. In debuffered rats, carperitide (1.0-mu-g/kg/min) also produced a mild decrease in mean arterial pressure. No significant changes in cardiac sympathetic nerve activity or heart rate were observed. A significant correlation between changes in heart rate and cardiac sympathetic nerve activity was noted during infusion of carperitide and deafferentation did not alter this relationship. In contrast, no significant correlation was observed between changes in cardiac sympathetic nerve activity and blood pressure during infusion of carperitide in either buffer nerve intact or debuffered rats. These results suggest that the reduction of blood pressure induced by intravenous infusion of carperitide may not trigger the baroreceptor-mediated cardiac sympathoexcitation and this inhibition of baroreflex may be responsible for the anti-tachycardic effect of carperitide.