Hyperresponsiveness of arterial rings induced by renal prehypertensive rabbit plasma

Vascular rings from normal rabbit renal arteries, when bathed in processed plasma from 3-day renal artery stenosis (RAS) rabbits, had greater contractile responses to norepinephrine than did matched rings bathed in processed plasma from sham-operated rabbits. This vascular hyperresponsiveness of the rings produced by 3-day RAS plasma was abolished by the angiotensin II (ANG II) antagonist [Sar1, Ile8] ANG II but not by [Sar1, Ala8] ANG II at a dose that completely blocked the contractile responses of the rings to ANG II. The addition of [Sar1, Ala8]-ANG II to rings bathed in normal rabbit plasma did not alter the contractile responses to norepinephrine, indicating a lack of agonistic action by this ANG II analogue. These studies demonstrated that the ANG II receptors involved in the hormonally mediated vascular hyperresponsiveness in 3-day RAS rabbits are contained in the tissues that comprise these renal arterial rings.