NONSELECTIVE CATION CHANNEL ACTIVATION DURING WOUND-HEALING IN THE CORNEAL ENDOTHELIUM

Rabbit corneas were injured by mechanical or thermal trauma. At severa l time points after wounding, corneal endothelial cells were isolated and their ion channels examined using standard and amphotericin perfor ated-patch whole cell patch-clamp configurations. Within 15-24 h after mechanical or thermal trauma, a nonselective cation current was obser ved in 79% of the cells examined that was not present in unwounded or sham-wounded corneas. By 73 h postwounding, the current was present in only 10% of the cells examined. The wound healing-induced current is outwardly rectifying, activates at depolarized voltages, shows no sign of inactivation, and is inhibited by flufenamic acid, quinidine, and acetate. In addition to this new current, it was observed that endothe lial cells from freeze-wounded corneas no longer expressed the transie nt K+ current seen in control, sham, and mechanically wounded corneas. Corneal endothelial superfusion experiments found no significant diff erence in swelling rates between control and flufenamic acid-superfuse d wounded corneas, indicating that the wound healing-induced channel i s not involved in the stromal hydration maintenance function of the co rneal endothelium.