Baroreceptor influences on plasma atrial natriuretic peptide (ANP): sinoaortic denervation reduces basal levels and the response to an osmotic challenge.

The objective of these studies was to investigate baroreceptor/osmotic interactions by determining the effect of sinoaortic denervation (SAD) on the ANP response to a hypertonic saline challenge in conscious rats. A time course study showed that there was a rapid increase in plasma ANP in response to iv hypertonic saline. The peak effect was at 5 min, a 3-fold increase (P less than .01). Baroreceptor denervation produced significant decreases in basal ANP levels and osmotic induced release (P less than 0.01). Plasma ANP increased from 25 +/- 3.2 to 136.8 +/- 28 in the sham-operated rats and from 11.8 +/- 2.6 to 30.8 +/- 4.6 in the SAD. Plasma sodium was the same in the 2 groups, and there was no change in atrial ANP content. Blood pressure was elevated in the denervated animals; however, the pressor response to the hypertonic challenge was not different from the controls. These results suggest that the baroreceptor system may have important influences on cardiovascular/hormonal regulation.