Altered stoichiometry of the human leucocyte Na+/H+ antiport with decreasing pH.
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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Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford, U.K.
Bomford
J
J
D002352:Carrier Proteins / Q000097:blood*; D055598:Chemical Phenomena; D002621:Chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007962:Leukocytes / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers