The relationship of K + efflux at the inner surface of the isolated frog skin epithelium to the short circuit current

Abstract

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.