19F-NMR study of primary human T lymphocyte activation: effects of mitogen on intracellular pH.
Intracellular pH of purified human T lymphocytes was studied using nuclear magnetic resonance (NMR) spectroscopy under physiological conditions. In this paper we introduce a new improved 19F-NMR pH probe, 2-amino-3,3'-difluoroisobutyric acid (vic-difluoro-alpha-methylalanine), which has a pKa of approximately 7.0, sensitivity of 0.83 ppm/pH, is noncytotoxic, and provides better signal-to-noise ratio for intracellular pH determinations. Quiescent and stimulated lymphocytes display different homeostatic intracellular pH values. Quiescent cells maintain intracellular pH of 7.04 +/- 0.03 at extracellular pH values between 6.9 and 7.3, and stimulated cells maintain intracellular pH of 7.25 +/- 0.05 at extracellular pH values between 7.0 and 7.5. Stimulation with ionomycin plus phorbol 12-myristate 13-acetate leads to intracellular alkalinization within 90 min, reaching the more alkaline steady-state value of 7.25 within 7-10 h. Proliferation, but not viability, of lymphocytes is dependent on extracellular pH in the range of 6.4-8.0, and this dependence is not due to limiting interleukin-2 elaboration. The mechanisms of pH regulation and the possible implications of a permissive pH for T lymphocyte proliferation are discussed.
Bental
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M
Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104.
Deutsch
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D000409:Alanine / Q000031:analogs & derivatives; D000613:Aminobutyrates; D005461:Fluorine; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism*; D008213:Lymphocyte Activation; D009682:Magnetic Resonance Spectroscopy; D008934:Mitogens / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
C086477:2-amino-3,3'-difluoroisobutyric acid; D000613:Aminobutyrates; D008934:Mitogens; D005461:Fluorine; D000409:Alanine