title: [Sar1Ile7]angiotensin III, a new selective antagonist of the pressor effect of angiotensin III in conscious rats.
abstract: Two analogues of angiotensin III were compared as antagonists of the pressor response to angiotensin II (ANG II) and angiotensin III (ANG III) in conscious, unrestrained rats. Dose-mean arterial pressure (MAP) response curves were obtained for ANG II and ANG III in the absence or presence of [Ile7]ANG III (1.3 x 10(-7) mol/kg) or [Sar1 Ile7]ANG III (1.2 x 10(-7) mol/kg). In the presence of [Ile7]ANG III, the dose-MAP response curves for ANG II and ANG III were significantly displaced to the right. [Ile7]ANG III behaved as a partial agonist on ANG II but not ANG III receptors. In the presence of [Sar1 Ile7]ANG III, the dose-MAP response curve for ANG III but not ANG II was significantly displaced to the right. This suggests that [Sar1 Ile7]ANG III is a selective antagonist of ANG III in the vasculature. [Ile7]ANG III, on the other hand, antagonizes both ANG II and ANG III receptors. Our results support the hypothesis of the existence of a sub-class of angiotensin receptors activated by ANG III in the vascular smooth muscle.
authors.affiliation: Department of Pharmacology & Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Tabrizchi
authors.forename: G J
authors.initials: GJ
authors.lastname: Moore
authors.forename: C C
authors.initials: CC
authors.lastname: Pang
mesh_terms: D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology; D000805:Angiotensin III / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000804:Angiotensin II; C056765:angiotensin III, Sar(1)-Ile(7)-; D000805:Angiotensin III; C056764:angiotensin III, Ile(7)-