RELATIONSHIP OF K+ EFFLUX AT THE INNER SURFACE OF THE ISOLATED FROG-SKIN EPITHELIUM TO THE SHORT-CIRCUIT CURRENT

Isolated frog skins (without chorion) were incubated with 42K+ Ringer's solution, bathing the internal surface for 2 h. All the K+ contained in the frog skin was equilibrated in specific activity with external 42K+. The kinetics of the washout of 42K+ from the internal surface of the skin exhibits one fast and one slow exponential component. Amiloride reduces the release of 42K+ corresponding to both components without affecting the K+ content of the skin. Ouabain increases the loss of 42K+ of the slow component by 200%. Since the total K+ in the skin decreases to 25% of its original value both compartments are affected. The results suggest that two distinct functional compartments exist defined by two 42K+ release ratios and that because of the large K+ contents of these compartments both are intracellular. The relation with the transepithelial Na+ transport and the morphological identification of these compartments is discussed. © 1979.