Endogenous angiotensin II enhances phenylephrine-induced tone in hypertensive rats

Abstract

Subthreshold concentrations of angiotensin II (Ang II) potentiate agonist- induced tone in a variety of blood vessels. We measured in vivo the mesenteric artery diameter and blood flow in 12-week-old normotensive Wistar- Kyoto (WKY) rats (n=20) and spontaneously hypertensive rats (SHR, n=20); systemic blood pressure was monitored continuously. Phenylephrine (10 μmol/L) superfused on the exteriorized mesentery reduced arterial diameter from 480±40 to 256±18 μm (P