title: Solubilization and characterization of endothelin-1 receptors in rat cardiac tissue.
abstract: Adult rat cardiac endothelin-1 (ET-1) receptors were solubilized with 0.5% digitonin and then characterized. The receptors retained binding activity after solubilization. Binding was saturable (KD of 0.065 +/- 0.004 nM, Bmax of 94.6 +/- 4.5 fmol/mg protein; Hill coefficient of 0.987 +/- 0.017 n = 6) and pH dependent, with the binding increasing as the pH was decreased from 10 to 4, but decreasing dramatically as pH dropped to 2. Specifically bound [125I]-ET-1 was not dissociated by 2 x 10(-7) M unlabelled ET-1, but was dissociated by pH 10 and 2. Returning the pH to 7.4 restored the binding activity of the receptors. Unlabelled ET-1 (10(-12) - 10(-7) M) and sarafotoxin S6b(10(-12) - 10(-7) M) competed with [125I]-ET-1 for binding to the receptors.
authors.affiliation: Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia.
authors.forename: J J
authors.initials: JJ
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Kelly
authors.forename: D J
authors.initials: DJ
authors.lastname: Casley
authors.forename: C I
authors.initials: CI
authors.lastname: Johnston
authors.forename: W G
authors.initials: WG
authors.lastname: Nayler
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D004072:Digitonin; D016232:Endothelins; D004730:Endothelium, Vascular; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000302:isolation & purification* / Q000378:metabolism; D017466:Receptors, Endothelin
chemical_list: D016232:Endothelins; D010455:Peptides; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D004072:Digitonin