Plasma membrane charging of Jurkat cells by nanosecond pulsed electric fields |
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Authors: | Jody A White Uwe Pliquett Peter F Blackmore Ravindra P Joshi Karl H Schoenbach Juergen F Kolb |
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Institution: | (1) Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA;(2) Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA, USA;(3) Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, USA; |
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Abstract: | The initial effect of nanosecond pulsed electric fields (nsPEFs) on cells is a change of charge distributions along membranes.
This first response is observed as a sudden shift in the plasma transmembrane potential that is faster than can be attributed
to any physiological event. These immediate, yet transient, effects are only measurable if the diagnostic is faster than the
exposure, i.e., on a nanosecond time scale. In this study, we monitored changes in the plasma transmembrane potential of Jurkat
cells exposed to nsPEFs of 60 ns and amplitudes from 5 to 90 kV/cm with a temporal resolution of 5 ns by means of the fast
voltage-sensitive dye Annine-6. The measurements suggest the contribution of both dipole effects and asymmetric conduction
currents across opposite sides of the cell to the charging. With the application of higher field strengths the membrane charges
until a threshold voltage value of 1.4–1.6 V is attained at the anodic pole. This indicates when the ion exchange rates exceed
charging currents, thus providing strong evidence for pore formation. Prior to reaching this threshold, the time for the charging
of the membrane by conductive currents is qualitatively in agreement with accepted models of membrane charging, which predict
longer charging times for lower field strengths. The comparison of the data with previous studies suggests that the sub-physiological
induced ionic imbalances may trigger other intracellular signaling events leading to dramatic outcomes, such as apoptosis. |
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