23Na NMR measurement of the maximal rate of active sodium efflux from human red blood cells.
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.
Knubovets
T L
TL
Institute of Chemical Physics, Academy of Science USSR, Moscow.
Revazov
A V
AV
Sibeldina
L A
LA
Eichhoff
U
U
D000255:Adenosine Triphosphate / Q000032:analysis; D004419:Dysprosium; D004912:Erythrocytes / Q000032:analysis / Q000201:enzymology / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D011122:Polyphosphates; D011188:Potassium / Q000493:pharmacokinetics; D012964:Sodium / Q000493:pharmacokinetics*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013054:Spectrophotometry, Atomic; D013997:Time Factors
D007202:Indicators and Reagents; D011122:Polyphosphates; D004419:Dysprosium; C048543:bis(tripolyphosphate)dysprosium(III); D000255:Adenosine Triphosphate; D012964:Sodium; D005954:Glucosephosphate Dehydrogenase; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium