title: Biphasic effects of angiotensin (1-7) and its interactions with angiotensin II in rat aorta.
abstract: Using isolated rat aortic rings perfused with Krebs-Henseleit saline, the vascular effects of angiotensin (1-7) (Ang [1-7]) and its interactions with angiotensin II (Ang II) were investigated. Ang (1-7) induced endothelium-dependent relaxation and vasodilating effects in preparations precontracted with phenylephrine. Without preconstriction, Ang (1-7) at high doses (10(-6) 10(-5) M) produced either a significant inhibition of Ang II-induced vasoconstriction or a non-tachyphylactic vasopressor response. While losartan inhibited the vasoconstriction induced by Ang (1-7), A779 blocked only its relaxation. Unlike losartan, blockade of AT(2)-receptors with PD 123319 had no effect. Taking into account the biphasic effects of angiotensin (1-7), we propose that it is one of the active components of the renin-angiotensin system, which is involved as a modulator both in the counter-regulatory actions of Ang II and in the self-regulation of its own vasodilating effects.
authors.affiliation: Labroatory of Experimental and Applied Physiology, The Romanian Academy Iasi, Iasi, Romania. ihaulica@yahoo.com
authors.forename: Ion
authors.initials: I
authors.lastname: Haulica
authors.forename: Walther
authors.initials: W
authors.lastname: Bild
authors.forename: Christian N
authors.initials: CN
authors.lastname: Mihaila
authors.forename: Teodor
authors.initials: T
authors.lastname: Ionita
authors.forename: Corneliu P
authors.initials: CP
authors.lastname: Boisteanu
authors.forename: Bogdan
authors.initials: B
authors.lastname: Neagu
mesh_terms: D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D004347:Drug Interactions; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D019808:Losartan / Q000494:pharmacology; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000959:Antihypertensive Agents; D007093:Imidazoles; D010446:Peptide Fragments; D011725:Pyridines; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; C073402:PD 123319; D000803:Angiotensin I; C118790:angiotensin I (1-7); D019808:Losartan