Direct effect of physiological doses of arginine vasopressin on the arterial wall in vivo.

Effects of topically applied arginine vasopressin (VPA), in 100-150 muU/ml blood concentration, on external diameter (D) and on dynamic elastic modulus (E*) of surgically denervated common carotid (CC) and femoral (FA) arteries have been studied before and after hypophysectomy in anesthetized dogs. Changes in D, E*, and flow resistance (R) of the CC and FA vascular beds before and after removal of the pituitary were also determined. It was found that VPA elicited a substantial (max 21-26%) decrease in E* and a smaller (max 5.9-6.9%) reduction in D of FA independent of the presence of absence of the pituitary gland. The VPA effect developed more rapidly after hypophysectomy than before. In the CC, VPA did not significantly affect values of E*. During the 1-h period after hypophysectomy, statistically significant decreases in E*-CC, E*-FA, and D-CC were observed, but D-FA did not change, although arterial pressure as well as R-FA and R-CC were diminished. These results give further support to physiological vascular actions of VPA and a possible role in short-term circulatory control. In large arteries, the effects of VPA also seem to be regionally differentiated.