title: Differential patterns of relaxation by synthetic atrial peptide (APII) in the pulmonary artery, ascending and distal abdominal aorta.
abstract: The vasodilatory effects of the synthetic rat atriopeptin (APII) have been studied in vitro in agonist-contracted, endothelium-denuded segments of the rat pulmonary artery, the ascending, and the distal abdominal aorta. In the pulmonary artery the contractures to methoxamine were inhibited more potently by APII (pD2 = 9.10 +/- 0.40, n = 6) than by the vasodilatory neuropeptide VIP (pD2 = 7.37 +/- 0.66, n = 6). The intrinsic activity of APII was 0.46 +/- 0.16 (n = 6). In segments previously exposed to either VIP or the beta 2-agonist salbutamol, APII was a near complete agonist (alpha = 0.82 +/- 0.17, n = 7 and 0.84 +/- 0.14, n = 6, respectively) without significant changes in the potencies. APII was a complete agonist also for the inhibition of the alpha-agonist-contracted segments of the aorta, however, with potencies 10-fold lower than in the pulmonary artery. VIP was without functionally significant effects in the aorta. The tachykinins (CGRP, SP, Neurokinins A and B) were without effects in all segments tested. In the ascending aorta, APII induced a long-lasting tachyphylaxis to the alpha-agonists, nearly completely abolishing the subsequent responsiveness to NA and methoxamine for more than 4 h.
authors.affiliation: Department of Physiology, University of Bergen, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Aardal
authors.forename: M
authors.initials: M
authors.lastname: Bråtveit
authors.forename: K B
authors.initials: KB
authors.lastname: Helle
mesh_terms: D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D001012:Aorta, Abdominal / Q000187:drug effects*; D005260:Female; D066298:In Vitro Techniques; D008729:Methoxamine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D015320:Tachykinins / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D000889:Anti-Arrhythmia Agents; D009842:Oligopeptides; D015320:Tachykinins; D014660:Vasoactive Intestinal Peptide; C029579:antiarrhythmic peptide; D008729:Methoxamine; D000420:Albuterol; D009638:Norepinephrine