Loss of fenamate-activated K+ current from epithelial cells during cornealwound healing

PURPOSE. The corneal epithelium provides a barrier between the external env ironment and the cornea. It also serves as an ion transporting epithelium. Because of its proximity with the external environment, the corneal epithel ium is frequently injured through physical or chemical insult. The purpose of this study was to determine whether corneal epithelial cell whole-cell c urrents change during corneal wound healing as the author of the present st udy has previously reported for corneal keratocytes and endothelial cells. METHODS. Rabbit corneal epithelial cells were injured by scraping, heptanol exposure, or freezing. The epithelium was allowed to heal for 12 to 74 hou rs. Cells were dissociated from corneas, and whole-cell currents were exami ned using the amphotericin-perforated-patch technique. RESULTS. Cells from the wounded corneal groups had significantly increased capacitance values, indicating increased surface area compared with that of control cells. As previously reported, the primary control whole-cell curr ent was a fenamate-activated K+ current. An inwardly rectifying K+ current and a Cl- current were also observed. In epithelial cells from heptanol-wou nded corneas, these conductances were generally unchanged. In cells from sc rape- and freeze-wounded corneas, however, the fenamate-activated current w as absent or significantly attenuated. CONCLUSIONS. AS they do in corneal keratocytes and endothelial cells, K+ ch annels disappear during some models of corneal epithelial wound healing. In addition, cell capacitance, a measurement of cell surface area, increases. These results suggest that substantial K+ channel activity is not required for in vivo epithelial cell proliferation during corneal wound healing.