Studies on chloride permeability of the skin ofLeptodactylus ocellatus: I. Na+ and Cl− effect on passive movements of Cl−

Summary The outflux of chloride through the isolated skin (J ₃₁ ^Cl ) of the South American frogLeptodactylus ocellatus (L.) is carried by a mechanism that saturates at high concentration of chloride on the inside, and is stimulated by the presence of Cl^– in the outer solution (trans side). The presence of Na⁺ on the outside, by itself, does not increaseJ ₃₁ ^Cl . However, whenJ ₃₁ ^Cl is already increased by chloride on thetrans side, the addition of Na⁺ produces a significant further increase. At low concentration of Cl^– on the outsideJ ₃₁ ^Cl proceeds through a route which involves changes in electrical parameters. The results suggest that both mechanisms are located on the cell membranes and, therefore, that the fluxes would cross through the cytoplasm of the cells. Na⁺ stimulates the second mechanism only.