Membrane chloride conductance and capacitance in Jurkat T lymphocytes during osmotic swelling.
Video microscopy and whole-cell patch-clamp recording were used to monitor changes in relative cell volume (V/Vo), chloride conductance (gCl), and membrane capacitance (Cm) during osmotically induced swelling in Jurkat T lymphocytes. Cellular swelling was initiated with hyperosmotic pipette solutions. Simultaneous evaluation of V/Vo and gCl revealed a 59-s delay between the inception of swelling and the activation of outwardly rectifying, ATP-dependent Cl- channels. Following the delay, increases in V/Vo and gCl progressed in parallel. In contrast, Cm, a measure of cell surface area, fell gradually at a rate of approximately 150 fF/min after whole-cell access was achieved. The decline in Cm lasted 200 s and was followed by a rapid rise (approximately 750 fF/min). The rise in Cm coincided with a variable increase in "leak" current, gCl increased at a slower rate and reached lower peak values in experiments performed without ATP; ATP had no effect on the biphasic Cm time course. The temporal separation of conductance and capacitance during swelling suggests that gCl and Cm vary independently, supporting the hypothesis that a large portion, if not all, of the whole-cell Cl- conductance activated during swelling is provided by volume-sensitive Cl- channels preexisting in the plasma membrane.
Ross
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PE
Department of Physiology and Biophysics, University of California, Irvine 92717.
Garber
S S
SS
Cahalan
M D
MD
D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D007700:Kinetics; D015458:Leukemia, T-Cell; D008433:Mathematics; D008954:Models, Biological; D009994:Osmolar Concentration; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
D018118:Chloride Channels; D002712:Chlorides