Electrical Fields in the Vicinity of Small Wounds in Notophthalmus viridescens Skin

Abstract

The transepithelial potential (TEP) across the skin of Notophthalmus viridescens hindlimb digits was measured in animals immersed in artificial pond water (APW) that was 1.5 mM in NaCl, 0.06 mM in KCl, and 0.1 mM in CaCl, before and after making a wound in the digit tip. Before wounding, the TEP of the digit skin averaged 35.3 mV ± 5.5 mV (S.E.M.), inside positive. After wounding, the TEP at locations distant from the wound approximated the TEP before wounding, but, at points progressively closer to the wound surface, the measured TEP was progressively less. The slope of this change in TEP, the lateral wound potential, averaged 41.7 mV/mm ± 9.5 mV/mm, with the regions closer to the wound being more negative than those away from the wound. When the Na channels of the outer surface of the external epidermal cells were blocked with benzamil (30 µM in APW), the TEP of the unwounded skin was reversed, to an average of - 14.1 mV ± 3.7 mV (inside negative). After benzamil-blocked digits were wounded, the lateral wound potentials averaged -21.5 mV/mm ± 4.0 mV/mm, with the polarity reversed: regions close to the wound were more positive than those away from the wound. The magnitudes of both the normal and the reversed wound fields are greater than those known to promote the migration of cells in vitro. What remains to be determined is how Notophthalmus viridescens epidermal cells and fibroblasts behave in such fields, and how this behavior relates to the process of wound healing under normal and modulated wound field conditions.

The involvement of Ca2+ and integrins in directional responses of zebrafish keratocytes to electric fields

“…Thus, the endogenous wound current at the wound site is likely to be greater than 26 mA cm À2 . In the amphibian, Notophthalmus viridescens, skin wounds caused outward currents of 21 mA cm À2 (Rhodes et al, 1990), which resulted in measured lateral EFs adjacent to wounds of 60 mV mm À1 (Chiang et al, 1989). The intrinsic EFs in the newt were shown to be required for normal wound healing (Sta Iglesia et al, 1996).…”

Electric field effects on human spinal injury: Is there a basis in the in vitro studies?

“…Significant EFs within the tissues near amphibian wounds have been directly measured. In an amputated newt limb, an EF of 60 mV/mm was measured over the first 125 lm adjacent to the edge of the cut within the tissues (McGinnis and Vanable, 1986) and the magnitude of the field fell in half in about 1 h. Small wounds to newt digits resulted in EFs that averaged 42 mV/mm (Chiang et al, 1989). When the digit of the newt was amputated, EFs averaging 89 mV/mm were measured within 100 lm of the cut surface (Sta Iglesia et al, 1996).…”

Endogenous lateral electric fields around bovine corneal lesions are necessary for and can enhance normal rates of wound healing

“…These results support the hypothesis that these endogenous fields may influence in vivo cell migration, thereby influencing the development and repair of the organism .The role of these fields in wound healing has been studied in amphibians . [3][4][5][6][7] In the newt, nullification or even decreasing the strengths of the electric fields by 50% significantly decreased the rate of new wound epithelization . s,7 However, increase of the strengths beyond normal levels did not enhance healing.…”