1. Epithelium is a battery
Epithelium is a battery. Skin and other epithelia maintain an electric potential difference across them due to active ion transport. (A) Epithelium of the cornea pumps Na+ to the basal side and Cl– to the apical side. The transport of those ions generates an electric potential difference, positive at the basal side relative to the apical side. (Modified from Levin, MH, Kim, JK, Hu, J, et al: Potential difference measurements of ocular surface Na+ absorption analyzed using an electrokinetic model. Invest Ophthalmol Vis Sci 2006; 47:306–316.) (B) Diagram of Na+ transporting syncytial epithelium in frog skin. Sodium ions enter the outer cells (top) of the epithelium via Na+ channels in the outer membranes of these cells, migrating along a steep electrochemical gradient. Once in the cell, they can diffuse to other cells of the epithelium via gap junctions that link the cells of the epithelium, and they can be actively transported from all of these cells via electrogenic pumps that are in all of the plasma membranes of the epithelium except the outer membrane with the Na+ channels. This results in a transport of Na+ from the water bathing the epithelium to the internal body fluids of the animal and the generation of a 50-mV potential across the epithelium. Tight junctions between cells at the outer edge of the epithelium minimize the escape of the positive charge transported inward and therefore minimize the collapse of the potential generated by the epithelium's electrogenic Na+ transport. (Modified from Vanable, JW, Jr: Integumentary potentials and wound healing. In: Borgans, RB, et al (eds): Electric Fields in Vertebrae Repair. New York, Alan R. Liss, 1989.)
Source: Endogenous and Exogenous Electrical Fields for Wound Healing, Wound Healing Evidence-Based Management, 4e
Citation: McCulloch JM, Kloth LC. Wound Healing Evidence-Based Management, 4e; 2010 Available at: Accessed: October 15, 2017
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