Altered stoichiometry of the human leucocyte Na+/H+ antiport with decreasing pH. |
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| Authors: | L L Ng and J Bomford |
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| Affiliation: | Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford, U.K. |
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| Abstract: | The Na+/H+ antiport is an important regulator of cellular volume, pH and Na+ concentration in mammalian cells. The stoichiometry of this antiporter has previously been shown to be a 1:1 exchange of internal H+ for external Na+. We have investigated this stoichiometry in human leucocytes by using a novel intracellular pH-clamping technique and measuring 22Na+ influx and H+ efflux in the same cells. As internal pH was lowered, the stoichiometry of H+/Na+ exchange rose to a mean +/- S.D. of 2.23 +/- 0.69. This mechanism allows a higher H+ efflux in the face of intracellular acid stress without causing excessive intracellular Na+ overload. |
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