Altered stoichiometry of the human leucocyte Na super(+)/H super(+) antiport with decreasing pH

The Na super(+)/H super(+) antiport is an important regulator of cellular volume, pH and Na super(+) concentration in mammalian cells. The stoichiometry of this antiporter has previously been shown to be a 1:1 exchange of internal H super(+) for external Na super(+). The authors have investigated this stoichiometry in human leucocytes by using a novel intracellular pH-clamping technique and measuring super(22)Na super(+) influx and H super(+) efflux in the same cells. This mechanism allows a higher H super(+) efflux in the face of intracellular acid stress without causing excessive intracellular Na super(+) overload.