Reversed potentials in isolated frog skin. II. Active transport of chloride

Abstract Net inward transport of Cl in the absence of an electrochemical potential difference was demonstrated in the skin of two species of frog, R. pipiens and R. esculenta under conditions of low (2 mM) Cl concentration in the bathing solutions. The electrical potential profile of skins of R. pipiens was examined with microelectrodes under conditions in which the inside solution was negative relative to the outside solution. This reversal of the normal potential difference was found to arise as a result of potential changes across the outward facing electrical barriers in the skin. The reversed potential difference appears to arise, at least in part, as a result of the inward Cl transport. The effect may be due either to electrogenic Cl transfer or to variations in internal composition of the epithelial cells arising as a result of Cl transport.