Carotid sinus pressure and plasma vasopressin in anesthetized rabbits

Abstract

The arterial baroreceptors are known to influence the release of vasopressin, but the quantitative relationship between baroreceptor stimulation and plasma vasopressin concentration has not been defined. These experiments examine the effect of stepwise changes in carotid sinus pressure (40-160 mmHg) on the plasma concentration of vasopressin in chloralose-urethan anesthetized rabbits. Plasma vasopressin concentration (9.2 +/- 1.2 pg/ml, n = 27) did not change in response to changes in carotid sinus pressure when the aortic depressor nerves were intact. These results were unaltered by bilateral cervical vagotomy. However, after aortic depressor nerve section, decreases in carotid sinus pressure were associated with increases in plasma vasopressin concentration. There appeared to be a greater redundancy in the baroreceptor control of plasma vasopressin than in the baroreceptor control of arterial pressure or heart rate. The results provided no evidence that receptors with vagal afferents have a tonic influence on the baroreceptor control of vasopressin release in the anesthetized rabbit.