Electric field-induced functional reductions in the K+ channels mainly resulted from supramembrane potential-mediated electroconformational changes.
The goal of this study is to distinguish the supramembrane potential difference-induced electroconformational changes from the huge transmembrane current-induced thermal damages in the delayed rectifier K+ channels. A double Vaseline-gap voltage clamp was used to deliver shock pulses and to monitor the channel currents. Three pairs of 4-ms shock pulses were used to mimic the electric shock by a power-line frequency electric field. Each pair consists of two pulses with the same magnitude, starting from 350 to 500 mV, but with opposite polarities. The shock pulse-generated transmembrane ion flux and the responding electric energy, the Joule heating, consumed in the cell membrane, as well as the effects on the K+ channel currents, were obtained. Results showed that huge transmembrane currents are not necessary to cause damages in the K+ channel proteins. In contrast, reductions in the K+ channel currents are directly related to the field-induced supramembrane potential differences. By a comparison with the shock field-induced Joule heating effects on cell membranes, the field-induced supramembrane potential difference plays a dominant role in damaging the K+ channels, resulting in electroconformational changes in the membrane proteins. In contrast, the shock field-induced huge transmembrane currents, therefore the thermal effects, play a secondary, trivial role.
Chen
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W
Departments of Dermatology and Physiology and Biophysics, The University of Illinois at Chicago, Chicago, Illinois 60612, USA. weichen@uic.edu
Han
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Y
Chen
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Astumian
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D
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002462:Cell Membrane / Q000378:metabolism; D004553:Electric Conductivity; D004560:Electricity; D004563:Electrochemistry; D018274:Electroporation; D006358:Hot Temperature; D066298:In Vitro Techniques; D017136:Ion Transport; D008564:Membrane Potentials; D018482:Muscle, Skeletal / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D011896:Rana temporaria; D011898:Ranidae
D015221:Potassium Channels