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Research Article Free access | 10.1172/JCI113037

Properties of the Na+-K+ pump in human red cells with increased number of pump sites.

J A Halperin, C Brugnara, A S Kopin, J Ingwall, and D C Tosteson

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Published July 1, 1987 - More info

Published in Volume 80, Issue 1 on July 1, 1987
J Clin Invest. 1987;80(1):128–137. https://doi.org/10.1172/JCI113037.
© 1987 The American Society for Clinical Investigation
Published July 1, 1987 - Version history
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Abstract

We studied the Na+/K+ pump in red cells from an obese human subject (MAJ) in which the number of pumps/cell was 10-20 times higher than normal. Through measurements of the kinetic properties of several modes of operation of the Na+/K+ pump we determined that the pumps in MAJ cells are kinetically normal. In the presence of adequate metabolic substrate the maximum rates of Na+ pumping and lactate production saturated at 60 and 12 nmol/1 cell per h, respectively. Under physiological conditions pump and "leak" Na+ fluxes were similar in MAJ and normal cells. Since internal Na+ was lower in MAJ than in normal cells (Nai+ approximately 2 and 8 mmol/1 cell, respectively), we conclude that the reduction in cell Na+ allows the Na+/K+ pump in MAJ cells to operate at lower fraction of maximum capacity and to compensate for the increased number of pumps.

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