title: Characterization of a Na+/K+-ATPase inhibitor from human plasma: preliminary data.
abstract: The role of an endogenous sodium pump inhibitor in the pathogenesis of hypertension has been reported in several papers. Unfortunately, because of the unknown structure and lack of biochemical characterization, some discrepancies have arisen. In this study we report a method to obtain extracts from human plasma that are able to inhibit Na+/K+-ATPase in vitro. Preliminary characterization was carried out, which showed that the extracts are able to inhibit Na+/K+-ATPase, pNPPase, and [3H]ouabain binding to red blood cells. The enzyme inhibition is not due to vanadate, FFA, or bivalent cations, and it seems to be reversible, dose-dependent, and largely prevented in E1 conformation of the enzyme. These results seem to support the hypothesis that human plasma contains a sodium pump inhibitor with many characteristics of a "ouabainlike" compound.
authors.affiliation: Department of Clinical Pharmacology and Therapeutics, University of Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Boschi
authors.forename: A
authors.initials: A
authors.lastname: Munarini
authors.forename: C
authors.initials: C
authors.lastname: Borghi
authors.forename: E
authors.initials: E
authors.lastname: Strocchi
authors.forename: F V
authors.initials: FV
authors.lastname: Costa
authors.forename: A
authors.initials: A
authors.lastname: Mussi
authors.forename: A
authors.initials: A
authors.lastname: Ettore
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D010949:Plasma / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014020:Tissue Extracts / Q000494:pharmacology
chemical_list: D014020:Tissue Extracts; D000254:Sodium-Potassium-Exchanging ATPase