Angiotensin receptors and pressor hyperresponsiveness in renal prehypertensive rabbits.
This study consisted of five different experiments with conscious rabbits. In experiment 1, the angiotensin II (ANG II) antagonist [Sar1-Ala8]ANG II infused iv into one-kidney rabbits with renal artery stenosis (RAS) of 3 days' duration, at a dose that blocked pressor responses to ANG II, did not decrease the exaggerated pressor responses to norepinephrine (NE). In experiment 2, captopril infused iv into one-kidney, 3-day, RAS rabbits blocked pressor hyperresponsiveness to NE, and the concurrent infusion of [Sar1-Ala8]ANG II did not reestablish pressor hyperresponsiveness, indicating that this ANG II analogue had no agonistic action to promote hyperresponsiveness to NE. In experiment 3, infusion of ANG II at a subpressor dose (6.7 pmol . min-1 . kg body wt-1) into normal rabbits resulted in pressor hyperresponsiveness to NE, which was blocked by [Sar1-Ala8]ANG II. Experiment 4 involved infusing [Sar1-Ala8]ANG II or [Sar1-Ile8]ANG II at various doses into 3-day RAS rabbits, to determine their abilities to attenuate the pressor responses to ANG II (100 ng/kg) and the pressor hyper-responses to NE (800 ng . min-1 . kg-1). [Sar1-Ile8]ANG II decreased the ANG II pressor responses at an ID50 dose of 64 +/- 5 (SEM) pmol . min-1 . kg-1 and attenuated the NE pressor hyper-response at an ID50 dose of 65 +/- 5 pmol . min-1 . kg-1; [Sar1-Ala8]ANG II diminished the ANG II pressor response at an ID50 dose of 757 +/- 247 and the NE pressor hyper-response at an ID50 dose of 10,061 +/- 944 pmol . min-1 . kg-1.(ABSTRACT TRUNCATED AT 250 WORDS)
D000804:Angiotensin II / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D006977:Hypertension, Renal / Q000209:etiology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D011945:Receptors, Angiotensin / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D012078:Renal Artery Obstruction / Q000503:physiopathology; D012504:Saralasin / Q000378:metabolism
D011945:Receptors, Angiotensin; D011956:Receptors, Cell Surface; D000804:Angiotensin II; C032651:angiotensin II, Sar(1)-Ile(5)-; D012504:Saralasin; D009638:Norepinephrine