A previous study has suggested that atrial natriuretic peptide (ANP) alters arterial baroreflex control of lumbar and renal sympathetic nerve activity. To explore these mechanisms, we examined the interrelationship of arterial pressure, afferent aortic nerve activity, and aortic diameter in the rabbits anesthetized with α-chloralose before and after sinoarotic denervation and bilateral vagotomy. Arterial pressure was decreased in stepwise fashion by intravenous infusion of α-human ANP (α-hANP, 0.1-1.0 μg/kg/min) or sodium nitroprusside (SNP, 1-5 μg/kg/min). Both in rabbits with intact baroreceptors and in those with baroreceptors denervated, aortic nerve activity and the aortic diameter decreased during hypotension caused by the infusion of SNP but remained unchanged during hypotension caused by the infusion of α-hANP. In addition, we examined the effects of α-hANP and SNP on the responses of the aortic diameter and aortic nerve activity to rapid changes in arterial pressure caused by intravenous phenylephrine or nitroglycerin. Changes in aortic nerve activity and the aortic diameter in response to rapid changes in arterial pressure caused by phenylephrine or nitroglycerin were not different between the infusion of α-hANP and SNP. These results suggest that aortic nerve activity remains unchanged despite hypotension during the infusion of α-hANP, because α-hANP dilates the aorta. Since the aortic diameter increases, strain of aortic baroreceptors does not decrease. A second suggestion is that α-hANP does not alter aortic baroreceptor responses to changes in arterial pressure caused by phenylephrine or nitroglycerin.
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine