title: Characterization of avian angiotensin II cardiac receptors: coupling to mechanical activity and phosphoinositide metabolism.
abstract: We have characterized the avian angiotensin II (AII) cardiac receptor and provide data that this receptor couples to both mechanical activity and phospholipid metabolism in the avian heart. In 10-day-old chicks, 125I-AII bound to a high affinity site (Kd = 10 nmol) and a low affinity site (Kd = 79.4 nmol) with estimated binding capacities of 531 and 1330 fmol/mg protein, respectively. The 125I-AII binding was rapid, saturable, reversible and modulated by divalent cations and guanine nucleotides. The potency order for the competitive binding of angiotensin I and II paralleled that observed for in vitro contractile force development in bioassays utilizing left atrial tissue. In avian heart, AII also produced a dose-dependent accumulation of inositol-1-phosphate which was inhibited by the angiotensin antagonist [Sar1, Ile8]AII. The data demonstrate specific avian AII cardiac receptors and provide the first evidence that these receptors couple to both mechanical activity and phosphoinositide metabolism in avian heart.
authors.affiliation: Weis Center for Research, Geisinger Clinic, Danville, PA 17822.
authors.forename: K M
authors.initials: KM
authors.lastname: Baker
authors.forename: J A
authors.initials: JA
authors.lastname: Aceto
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002645:Chickens; D066298:In Vitro Techniques; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D011945:Receptors, Angiotensin / Q000378:metabolism*
chemical_list: D010716:Phosphatidylinositols; D011945:Receptors, Angiotensin