The Journal of Cell Biology, Vol 98, 885-893, Copyright © 1984 by The Rockefeller University Press
pH homeostasis in human lymphocytes: modulation by ions and mitogen
C Deutsch, JS Taylor and M Price
Quiescent human peripheral blood lymphocytes have been shown to maintain a
relatively constant intracellular pH of 7.0-7.2 over an extracellular pH
range of 6.9-7.4. Two methods of measuring intracellular pH were used in
these studies, 19F nuclear magnetic resonance and
[14C]5,5-dimethyloxazolidine-2,4-dione (DMO) equilibrium distributions.
When ATP levels were decreased in these cells, actively maintained pH
regulation was abolished and cells exhibited a constant pH gradient of 0.2
pH unit (acid inside relative to outside). Possible mechanisms for pH
regulation are discussed. The effects of the Na+ and K+ composition of the
medium on pH regulation showed no correlation with their effects on
mitogen-induced proliferative response, which we have previously determined
(Deutsch, C., and M. Price, 1982, J. Cell. Physiol., 111:73-79). In low-Na+
mannitol medium, pH regulation was similar to that observed for lymphocytes
in normal medium, whereas mitogen-induced proliferation was severely
inhibited in low-Na+ mannitol. In contrast, high-K+, low Na+ medium caused
loss of pH homeostasis, whereas it restored the proliferative response.
Loss of pH homeostasis was also observed on prolonged exposure of
lymphocytes to mitogen (greater than 6 h in culture). However, mitogen
stimulation led to little or no change in intracellular pH in the first few
hours of cell culture. Therefore, a shift in intracellular pH is not a
necessary or general event in mitogen-stimulated proliferation of
lymphocytes.
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