Abstract: The whole cell patch technique was applied to Jurkat cells, a human leukemic T-lymphocyte cell line. From a holding potential of 70 mv, a sequence of depolarizing square voltage pulses ranging from 0 to 130 mv., spaced 10 mv apart and of duration 190ms., was applied to the cell membrane and the resulting currents measured. Peak currents as high as two nanoamps could be obtained from some cells while other cells showed barely detectable currents in response to 130 mv. depolarizing pulses. The shape of the current responses to the large depolarizing pulses varied greatly from cell to cell. Some cells showed current vs. time curves with broad peaks with latency to the peak of about 12 ms and other cells showed narrow peaks with latency to the peak of less than 5 ms. The reasons for this variability are not clear but may reflect the stage of the cell cycle when the patch was made as the cultures were in log phase during our studies. In addition to square pulses, trapezoidal voltage wave forms were applied to the cell and the evoked currents were measured. In some experiments of this sort there appeared to be a negative resistance region of the current voltage curve. Also, it may be possible to interpret the current vs. time records evoked by the trapezoidal voltage wave forms in terms of a variable capacitance. These points may become clearer when adequate electrical models of preparation are made. Under zero current clamp, the membrane voltage fluctuates with time. This phenomenon may be related to the negative resistance sometimes observed....T-Lymphocyte, Membrane potential, Electrophysiology, Voltage clamp.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Description: |
Technical rept. 1991-1992 |
| Pages: |
28 |
| Report Date: |
APR 93 |
| Report Number: |
A292462 |
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