23Na NMR measurement of the maximal rate of active sodium efflux from human red blood cells

• Published in: Magnetic resonance in medicine Vol. 9; no. 2; p. 261
• Main Authors: Knubovets, T L, Revazov, A V, Sibeldina, L A, Eichhoff, U
• Format: Journal Article
• Language: English
• Published: United States 01.02.1989
• Subjects: Adenosine Triphosphate - analysis; Dysprosium; Erythrocytes - analysis; Erythrocytes - enzymology; Erythrocytes - metabolism; Glucosephosphate Dehydrogenase - metabolism; Hemolysis; Humans; Indicators and Reagents; Magnetic Resonance Spectroscopy; Polyphosphates; Potassium - pharmacokinetics; Sodium - pharmacokinetics; Sodium-Potassium-Exchanging ATPase - metabolism; Spectrophotometry, Atomic; Time Factors
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.1910090211

The method for 23Na NMR measurement of the maximal rate of active Na+ efflux from human red blood cells (RBC) is proposed. The nonpenetrating paramagnetic shift reagent (SR) bis(tripolyphosphate)dysprosium(III) complex is used to distinguish extracellular Na+ ions from intracellular. RBC are proved to retain their physiological activity in the presence of SR. Intracellular Na+ is shown to be 100% NMR visible. The levels of intracellular and extracellular Na+ and K+ ions are changed to decrease their concentration gradients across the erythrocyte membrane to make active Na+ efflux the only 23Na NMR measurable process; so the integrated areas of intra- and extracellular Na+ peaks remain invariant throughout the incubation period in the presence of 0.25 mM ouabain, a specific inhibitor of Na+, K+-ATPase. The accuracy of the proposed technique is evaluated to be 10%. The maximal Na+ efflux is determined to be 10.1 +/- 1.0 mM/h/liter of cells.