title: A beta-2-adrenergic receptor activates adenylate cyclase in human erythrocyte membranes at physiological calcium plasma concentrations.
abstract: More information is needed about the subtype of the beta-adrenergic receptor coupled to the G-protein-adenylate cyclase (AC) system in human erythrocytes and about the optimal experimental conditions to study this system. In this study we describe the characteristics of spontaneous and beta-agonist-activated AC in human erythrocytes. Human erythrocyte membranes were isolated and AC activity was utilized to assess the quantity of cAMP. Our data show that the subtype beta-2 is the functional beta-adrenergic receptor involved in such activation; this modifies the beta-adrenergic-stimulated activity of AC in human erythrocytes. Isoproterenol in a medium with calcium (1-10 mM, range that includes physiological plasma concentrations) enhances the activation of AC; this effect was blocked by propranolol, but not by atenolol. We conclude that in human erythrocytes subtype beta-2 is the functional beta-adrenergic receptor and that such a response depends to a large extent on Ca(2+) concentrations.
authors.affiliation: Department of Pharmacology and Therapeutics, University Miguel Hernández, San Juan, Alicante, Spain. jfhorga@umh.es
authors.forename: J F
authors.initials: JF
authors.lastname: Horga
authors.forename: J
authors.initials: J
authors.lastname: Gisbert
authors.forename: J C
authors.initials: JC
authors.lastname: De Agustín
authors.forename: M
authors.initials: M
authors.lastname: Hernández
authors.forename: P
authors.initials: P
authors.lastname: Zapater
mesh_terms: D000262:Adenylyl Cyclases / Q000097:blood*; D001262:Atenolol / Q000494:pharmacology; D002118:Calcium / Q000097:blood*; D004910:Erythrocyte Membrane / Q000201:enzymology / Q000502:physiology*; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D018343:Receptors, Adrenergic, beta-2 / Q000097:blood*
chemical_list: D018343:Receptors, Adrenergic, beta-2; D008345:Manganese; D001262:Atenolol; D000262:Adenylyl Cyclases; D008274:Magnesium; D007545:Isoproterenol; D002118:Calcium; D009638:Norepinephrine