Chloride transport in amphibian skin: a review

1. The transport of Cl- ions across amphibian skin is a complex subject since it involves different mechanisms such as electrodiffusion, exchange diffusion and active transport. Cl- translocation occurs predominantly through a transcellular route, the paracellular pathway being of lesser importance. 2. Transcellular Cl- passage takes place mainly through specialized cells, the mitochondria-rich cells. The principal cells of the epithelium, the cells of the stratum granulosum, which handle most of the active transepithelial Na+ transport, have been shown to play an insignificant role in transepithelial Cl- transport. 3. It is accepted that the main limiting barrier to transepithelial Cl- movement is the apical membrane of the outermost epithelial cells. The apical membrane of the mitochondria-rich cells seems to be the site of a Cl- permeability which is modulated by voltage and Cl- ions.