title: 23Na-NMR study of cation cotransport in human red blood cells.
abstract: Na(+)-K+ cotransport in human erythrocytes from healthy subjects has been studied by means of 23Na-nuclear magnetic resonance (NMR) in the presence of the anionic paramagnetic shift reagent dysprosium (III) tripolyphosphate [Dy(PPP)2(7-)]. The intra- and extracellular 23Na-NMR signals were well separated, giving values of 6 +/- 1 mM for internal sodium concentration. Determination of the furosemide-sensitive Na+ efflux, in the presence of ouabain, was obtained by correlating the chemical shift variation of the external signal with changes in external Na+ concentration. For this purpose, calibration curves were generated. The values of the maximum efflux velocity (Vmax; 0.29-1 mmol.h-1.l cells-1) measured in 10 healthy adult male subjects were found to be within the range of values obtained by other authors. The NMR method proposed for the study of Na(+)-K+ cotransport is relatively simple and allows quick evaluation of cotransport Vmax values for a number of samples, being a good candidate for the study of this transport mechanism in the presence of different pathologies.
authors.affiliation: Istituto di I Clinica Medica, Facoltà di Medicina e Chirurgia, Università di Roma La Sapienza, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cacciafesta
authors.forename: V
authors.initials: V
authors.lastname: Marigliano
authors.forename: C
authors.initials: C
authors.lastname: Ferri
authors.forename: G
authors.initials: G
authors.lastname: Piccirillo
authors.forename: A
authors.initials: A
authors.lastname: Scuteri
authors.forename: L
authors.initials: L
authors.lastname: Guidoni
authors.forename: A M
authors.initials: AM
authors.lastname: Luciani
authors.forename: A
authors.initials: A
authors.lastname: Rosi
authors.forename: V
authors.initials: V
authors.lastname: Viti
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002138:Calibration; D002352:Carrier Proteins / Q000502:physiology; D002412:Cations / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D009994:Osmolar Concentration; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium; D028021:Sodium-Potassium-Chloride Symporters
chemical_list: D002352:Carrier Proteins; D002412:Cations; D028021:Sodium-Potassium-Chloride Symporters; D010042:Ouabain; D012964:Sodium