title: Direct determination of endothelin receptor antagonist levels in plasma using a scintillation proximity assay.
abstract: An assay using scintillation proximity bead technology has been developed suitable for the quantitation of endothelin (ET) receptor antagonists in preclinical and clinical samples of plasma. The assay measures the competitive inhibition of radiolabelled ET-1 binding to ET(A) receptor membranes bound to wheat germ agglutinin (WGA)-coated scintillation proximity assay (SPA) beads in the presence of plasma containing A-127722, a potent orally active, ET(A) selective ET antagonist. The assay requires as little as 50 microl plasma and no extraction procedure is needed. The SPA methodology eliminates the need for the separation of bound from free ligand. Using this method, A-127722 could be directly quantified in rat plasma with a detection limit of 1 ng/ml.
authors.affiliation: Metabolic Disease Research, Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, Illinois 60064, USA. brian.dayton@abbott.com
authors.forename: B D
authors.initials: BD
authors.lastname: Dayton
authors.forename: W J
authors.initials: WJ
authors.lastname: Chiou
authors.forename: T J
authors.initials: TJ
authors.lastname: Opgenorth
authors.forename: J R
authors.initials: JR
authors.lastname: Wu-Wong
mesh_terms: D000818:Animals; D000077868:Atrasentan; D016466:CHO Cells; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism; D006801:Humans; D011759:Pyrrolidines / Q000097:blood*; D011869:Radioligand Assay; D051381:Rats; D017466:Receptors, Endothelin / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D012588:Scintillation Counting; D013050:Spectrometry, Fluorescence
chemical_list: D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D011759:Pyrrolidines; D017466:Receptors, Endothelin; D011994:Recombinant Proteins; D000077868:Atrasentan