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Research Article Free access | 10.1172/JCI105635
Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina
‡Work done during the term of U. S. Public Health Service postdoctoral fellowship 5F2-AM-19,537.
Address requests for reprints to Dr. John R. Sachs, Department of Hematology, Division of Medicine, Walter Reed Army Institute of Research, Washington, D. C. 20007.
*Submitted for publication 9 February 1967; accepted 25 May 1967.
This work was supported by U. S. Public Health Service research grant 5 RO1 HE 01301 and training grant AM 05054.
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Published September 1, 1967 - More info
The effect of some cations on the active potassium transport system of the human red blood cell has been investigated. At low extracellular potassium concentrations, extracellular sodium competitively inhibits the active potassium influx at all sodium concentrations investigated, and tetraethylammonium behaves in a fashion similar to that of sodium. At low extracellular concentrations of potassium, ammonium at low concentrations at first stimulates the active potassium influx, but at higher concentrations inhibits it. Tetramethylammonium at most slightly stimulates the active potassium influx, and calcium is without effect. The behavior is consistent with a model in which potassium is required at more than one site before transport occurs, and the sites are indistinguishable as far as their behavior toward the ions investigated is concerned. The affinity of the alkali metal cations for the sites appears to be explicable in terms of their physical characteristics.