Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells

B. Sarkadi, J. K. Alifimoff, R. B. Gunn, D. C. Tosteson

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Abstract

This paper describes the kinetics and stoichiometry of a tightly coupled Na-Li exchange transport system in human red cells. The system is inhibited by phloretin and furosemide but not by ouabain. Li influx by this system increases and saturates with increasing concentrations of external Li and internal Na and is inhibited competitively by external Na. Comparable functions relate Li efflux and Na efflux to internal and external Li and Na concentrations. Analysis of these relations yields the following values for the ion concentrations required to half-maximally activate the transport system: internal Na and Li 9.0 and 0.5 mM respectively, external Na and Li 25 and 1.5 mM, respectively. The system performs a 1:1 exchange of Na and Li moving in opposite directions across the red cell membrane. No evidence was found for a simultaneous transport of more than one Na and Li by the system. The maximum transport rate of Na-dependent Li transport varied between 0.1 and 0.37 mmol/(liter of cells x hr) in the red cells of the 5 normal male subjects studied. No significant variations between individual subjects were observed for bicarbonate-stimulated Li transport and for the residual Li fluxes which occur in the absence of bicarbonate and in the presence of ouabain plus phloretin.

Original languageEnglish
Pages (from-to)249-265
Number of pages17
JournalJournal of General Physiology
Volume72
Issue number2
Publication statusPublished - 1978

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Phloretin
Erythrocytes
Ouabain
Bicarbonates
Furosemide
Cell Membrane
Ions
Direction compound

ASJC Scopus subject areas

  • Physiology

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Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells. / Sarkadi, B.; Alifimoff, J. K.; Gunn, R. B.; Tosteson, D. C.

In: Journal of General Physiology, Vol. 72, No. 2, 1978, p. 249-265.

Research output: Contribution to journalArticle

Sarkadi, B, Alifimoff, JK, Gunn, RB & Tosteson, DC 1978, 'Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells', Journal of General Physiology, vol. 72, no. 2, pp. 249-265.
Sarkadi, B. ; Alifimoff, J. K. ; Gunn, R. B. ; Tosteson, D. C. / Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells. In: Journal of General Physiology. 1978 ; Vol. 72, No. 2. pp. 249-265.
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