title: 23Na and 39K NMR studies of ion transport in human erythrocytes.
abstract: Ion transport in human erythrocytes was studied by 23Na and 39K NMR with an anionic paramagnetic shift reagent, Dy(P3O10)2(7-). The intra- and extracellular 23Na and 39K NMR signals were well separated (over 10 ppm) at 5 mM concentration of the shift reagent. The NMR visibility of the intracellular Na+ and K+ was determined to be 100% in human and duck erythrocytes. The intracellular ion concentrations were 8.1 +/- 0.8 mM Na+ (n = 7) and 110 +/- 12 mM K+ (n = 4) for fresh human erythrocytes. The ouabain-sensitive net Na+ efflux was 1.75 +/- 0.08 mmol/hr per liter of cells at 37 degrees C (n = 3). The gramicidin-induced ion transport in human erythrocytes was also studied by 23Na and 39K NMR or by simultaneous measurements of 23Na NMR and a K+-selective electrode. The time courses of the Na+ and K+ transport induced by the ionophore were biphasic. The initial rapid fluxes were due to an exchange of Na+ for K+, which were found to occur with a 1:1 stoichiometry. The subsequent slow components were the net Na+ and K+ effluxes rate-limited by the Cl- permeability and accompanied by a reduction in cell volume. The Cl- permeability determined from the NMR measurements of these slow fluxes was 3.2 +/- 0.5 X 10(-8) cm/sec at 25 degrees C (n = 4).
authors.forename: T
authors.initials: T
authors.lastname: Ogino
authors.forename: G I
authors.initials: GI
authors.lastname: Shulman
authors.forename: M J
authors.initials: MJ
authors.lastname: Avison
authors.forename: S R
authors.initials: SR
authors.lastname: Gullans
authors.forename: J A
authors.initials: JA
authors.lastname: den Hollander
authors.forename: R G
authors.initials: RG
authors.lastname: Shulman
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006096:Gramicidin / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood*
chemical_list: D006096:Gramicidin; D010042:Ouabain; D012964:Sodium; D011188:Potassium