title: Improved receptor assay for measuring digoxin activity.
abstract: We describe a receptor assay of digoxin activity involving Na+/K+-ATPase (EC 3.6.1.37) derived from human heart tissue. The procedure requires 500 microL of serum or plasma and incorporates one purification step, with Sep-Pak C18 cartridges (Waters). The method appears to be considerably more specific for digoxin and its cardio-active metabolites than are conventional immunoassays. Cardio-inactive metabolites and several digoxin-like factors cross react only slightly. The between-day coefficient of variation for the procedure ranged from 8.10% to 1.37% for digoxin concentrations between 0.5 and 5.0 nmol/L.
authors.affiliation: Research Institute Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Bednarczyk
authors.forename: S J
authors.initials: SJ
authors.lastname: Soldin
authors.forename: I
authors.initials: I
authors.lastname: Gasinska
authors.forename: M
authors.initials: M
authors.lastname: D'Costa
authors.forename: L
authors.initials: L
authors.lastname: Perrot
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D004077:Digoxin / Q000097:blood*; D004285:Dogs; D005227:Fatty Acids / Q000097:blood; D005454:Fluorescence Polarization; D006801:Humans; D007118:Immunoassay; D007668:Kidney / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D011869:Radioligand Assay / Q000592:standards; D000254:Sodium-Potassium-Exchanging ATPase; D013256:Steroids / Q000097:blood; D013552:Swine
chemical_list: D001798:Blood Proteins; D005227:Fatty Acids; D013256:Steroids; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase