Cellular responses to applied electric fields
Abstract
Electric fields are known to exist in developing embryos and around fresh epithelial wounds. We have investigated the responses to applied electric fields of cells which will be exposed to such electric fields in vivo. Zebrafish keratocytes migrated towards the cathode of in vitro applied EFs of physiological magnitude (7-100 mV/mm). The size of a keratocyte did not correlate with the degree of response to a given applied EF magnitude, suggesting that cells do not have a 'voltage sensor', but are responding to some effect of the EF in the medium. Multi-layered epidermal sheets migrated to the cathode in a manner indistinguishable from keratocytes isolated from these sheets. The mechano-sensitive ion channel blocker Gd3+, abolished response to an electric field, as did nifedipine. An EF opened ion channels that allowed FM 1-43 to enter keratocyte cell bodies. We propose a central role for mechano-sensitive ion channels in the response of zebrafish keratocytes to applied electric fields. Cultured embryonic zebrafish neurons did not respond to an applied electric field, either by increased growth rate or by turning towards either electrode. This is unlike Xenopus neurons in culture, suggesting that the response of Xenopus neurons to applied electric fields cannot be considered a universal feature of embryonic neurons. Drosophila neuroblast response to an applied electric field was variable, perhaps due to some unknown variation in culture conditions from day to day. We found that there was a role for calcium in the control of division of Drosophila neuroblasts. In the presence of 2 mM or 5 mM EGTA, a Ca2+ chelator which would greatly reduce the extracellular [Ca2+], localization of cell polarity proteins was not affected. The difference in size between neuroblasts and ganglion mother cells was reduced in Ca2+-free medium and in the presence of ≥ 6.67 μM BAPTA-AM.
Degree
Ph.D.
Advisors
Robinson, Purdue University.
Subject Area
Cellular biology
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