Molecular Mechanisms of Electric Signals Generated at Corneal Wounds

Over 150 years ago, it was demonstrated that wounds produce electric fields and currents. Recent research provides strong evidence that these electric fields send a powerful signal to guide the migration of cells and epithelial sheets to heal. However, the mechanisms by which wounds generate and regulate the electric signals are not known. Here, we demonstrate that cornea wound electric currents are an actively regulated wound response. Using a systematic and hierarchical drug screening strategy, starting with general inhibitors for channels/pumps of sodium, chloride, potassium, and calcium channels, we found an essential role for chloride channels. The flux of chloride ions contributes over 80% of the wound electric current, and the increase in chloride flux after cornea injury correlates with the rise of the wound electric signal. Next, utilizing more specific chloride channel blockers, we identified calcium-activated chloride channels (CaCCs) as playing an important role in generating the wound electric currents in rat cornea. Specific CaCC blockers dramatically and reversibly blocked the currents. In addition, using specific drugs which increase or decrease corneal epithelial cell internal calcium in turn enhanced or diminished, respectively, the wound electric current. The electric signals are also (both reversibly) energy-consuming and temperature-dependent. These data identify CaCCs as molecular generators that actively produce cornea wound electric currents, suggesting critical molecular links between calcium signaling, chloride channel activities, and wound electric fields in wound electrical signaling and wound healing.