Lack of voltage sensitive potassium channels and generation of membrane potential by sodium potassium ATPase in murine T lymphocytes.
Voltage sensitive K+ channels, which are responsible for generation of membrane potential in most cells, are functionally absent in about one-third of peripheral murine T cells and greatly reduced in the rest as shown by resistance of their membrane potential to changes in extracellular potassium concentration and failure of K+ channel dependent volume regulation. Despite the absence of voltage- sensitive K+ channels, the membrane potential of peripheral T cells is between -60 and -70 mV, the same as thymocytes. A total of 40 to 70 mV of the membrane potential of peripheral T cells is produced by the direct electrogenic action of the asymmetric Na+K+ ATPase pump because the cells are depolarized by ouabain, an inhibitor of the pump, removal of extracellular potassium or reduction of temperature. The residual, ouabain-resistant membrane potential, is sensitive to the K+ channel blocker, quinine, and thus due to electrodiffusion through K+ channels. Na+ and K+ turnover, and sensitivity to ouabain, are the same in peripheral T cells and thymocytes. The predominant mechanism of membrane potential generation changes during T lymphocyte differentiation from electrodiffusion in the thymus to electrogenic in peripheral T cells and back to electrodiffusion upon peripheral cell activation.
Ishida
Y
Y
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
Chused
T M
TM
D000818:Animals; D002138:Calibration; D002478:Cells, Cultured; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013601:T-Lymphocytes / Q000502:physiology*
D015221:Potassium Channels; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium