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Transmembrane calcium influx induced by ac electric fields
Author(s) -
Cho Michael R.,
Thatte Hemant S.,
Silvia Mary T.,
Golan David E.
Publication year - 1999
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.13.6.677
Subject(s) - calcium , transmembrane protein , chemistry , biophysics , microbiology and biotechnology , biology , biochemistry , receptor , organic chemistry
Exogenous electric fields induce cellular responses including redistribution of integral membrane proteins, reorganization of microfilament structures, and changes in intracellular calcium ion concentration ([Ca 2+ ] i ). Although increases in [Ca 2+ ] i caused by application of direct current electric fields have been documented, quantitative measurements of the effects of alternating current (ac) electric fields on [Ca 2+ ] i are lacking and the Ca 2+ pathways that mediate such effects remain to be identified. Using epifluorescence microscopy, we have examined in a model cell type the [Ca 2+ ] i response to ac electric fields. Application of a 1 or 10 Hz electric field to human hepatoma (Hep3B) cells induces a fourfold increase in [Ca 2+ ] i (from 50 nM to 200 nM) within 30 min of continuous field exposure. Depletion of Ca 2+ in the extracellular medium prevents the electric field‐induced increase in [Ca 2+ ] i , suggesting that Ca 2+ influx across the plasma membrane is responsible for the [Ca 2+ ] i increase. Incubation of cells with the phospholipase C inhibitor U73122 does not inhibit ac electric field‐induced increases in [Ca 2+ ] i , suggesting that receptor‐regulated release of intracellular Ca 2+ is not important for this effect. Treatment of cells with either the stretch‐activated cation channel inhibitor GdCl 3 or the nonspecific calcium channel blocker CoCl 2 partially inhibits the [Ca 2+ ] i increase induced by ac electric fields, and concomitant treatment with both GdCl 3 and CoCl 2 completely inhibits the field‐induced [Ca 2+ ] i increase. Since neither Gd 3+ nor Co 2+ is efficiently transported across the plasma membrane, these data suggest that the increase in [Ca 2+ ] i induced by ac electric fields depends entirely on Ca 2+ influx from the extracellular medium.—Cho, M. R., Thatte, H. S., Silvia, M. T., Golan, D. E. Transmembrane calcium influx induced by ac electric fields. FASEB J. 13, 677–683 (1999)