Arterial baroreceptors control blood pressure and vasopressin responses tohemorrhage in conscious dogs

The goal of this study was to determine the role of arterial baroreceptors in the reflex control of arginine vasopressin (AVP), renin, and cortisol se cretion in response to a 30-ml/kg hemorrhage in conscious dogs. The hormona l responses were measured in six dogs under four treatment conditions: 1) i ntact, 2) acute cardiac denervation (CD) by intrapericardial infusion of pr ocaine, 3) after sinoaortic denervation (SAD), and 4) during combined SAD CD. In the intact condition, mean arterial pressure (MAP) was maintained a t control levels until blood loss reached 20 ml/kg and the absolute magnitu de of the fall at 30 ml/kg was 35 +/- 10 mmHg. Similar responses were obtai ned during acute CD. In contrast, MAP fell earlier (at 5 ml/kg, P < 0.05) a nd to much lower levels in both the SAD and SAD + CD conditions. The indivi dual slopes relating systolic pressure to plasma AVP, renin activity (PRA), and cortisol were used to compare the treatment effects using a 2 X 2 fact orial analysis. There was a significant (P < 0.01) effect of SAD on the slo pe relating AVP to systolic pressure but no effect of CD and no SAD X CD in teraction. In contrast, there was no effect of either SAD or CD on the rela tionship between PRA or plasma cortisol and systolic pressure. These result s indicate that maintenance of blood pressure and the normal pattern of ANP secretion during hemorrhage depend on intact arterial baroreceptor reflexe s.