Figure 3.

Generation of wound-induced electric currents. When the skin is injured, the epithelial layer is disrupted locally, and the ionic gradient across the epithelium collapses at the wound site. A consequence of the disruption of the epithelial integrity is leakage of Na⁺ ions out of the wound, down their concentration gradient, and an uptake of Cl⁻ ions. The respective ion movements give rise to a physiological injury current that flows toward the wound center (defined as the movement of positive charge) and a lateral voltage gradient oriented parallel to the epithelial sheet (EF, electric field; green discontinuous arrow at bottom). The discontinuous red arrows indicate positive ion (current) flux through the cell layers and the return path. The wound is, therefore, more negatively charged and acts as a cathode (negative sign in figure) as compared with healthy tissue (which acts as the anode, positive sign in figure). For simplification, we only show the ionic flux loop and EF on the right side of the figure, although the same applies for the left side. These endogenously generated EFs contribute to the guidance of cells, blood vessels, and nerves toward the wound site. Based on Nuccitelli et al.¹³ and Shaw and Martin.¹⁵ To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound