Effect of intracellular pH on the rate of chloride uptake and efflux in different mammalian cell lines

The effect of the internal pH on the rate of 36Cl- uptake and efflux was measured. While the rate of 36Cl- uptake by the antiport increased almost 10-fold over a narrow pH range in a number of cell lines, in other cells the pH-induced increase was considerably less. With increasing pH, the rate of 36Cl- efflux into chloride-free buffers increased strongly over a narrow pH range in all cell lines studied. Two groups of cell lines appeared, one group where the half-maximal increase in uptake and efflux rate was at pH 7.0-7.1 and another group where the corresponding values were 0.2-0.4 pH unit higher. The stoichiometry between chloride influx and chloride-stimulated efflux was close to 1:1 under various conditions.