Vasopressin and angiotensin in the control of arterial pressure and regional blood flow in anaesthetized, surgically stressed rats.

The effects of vasopressin and angiotensin II in the control of regional blood flow (BF) in halothane-anaesthetized rats were investigated by the administration of specific antagonists of vasopressin and angiotensin II, namely, [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid), 2-(O-methyl)tyrosine] arginine-vasopressin [d(CH2)5 Tyr(Me) AVP] and saralasin, respectively. Cardiac output and the distribution of BF was examined by the reference sample microsphere technique. The injection of the vasopressin antagonist into the left ventricle of rats caused reductions of mean arterial pressure (MAP) and total peripheral resistance (TPR), an increase of BF to the stomach and skin and a decrease of BF to the intestine. Intravenous infusion of saralasin caused reductions of MAP and TPR and an increase of BF to the kidneys and skin. The results show that both the vasopressin and the renin-angiotensin systems participate in the control of arterial pressure and peripheral vascular resistance in anaesthetized, surgically stressed rats.