AJP - Cell Physiology, Vol 262, Issue 5 C1292-C1296, Copyright © 1992 by American Physiological Society
23Na-NMR study of cation cotransport in human red blood cells
M. Cacciafesta, V. Marigliano, C. Ferri, G. Piccirillo, A. Scuteri, L. Guidoni, A. M. Luciani, A. Rosi and V. Viti
Istituto di I Clinica Medica, Facolta di Medicina e Chirurgia, Universita di Roma La Sapienza, Italy.
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.
