K+-permeability of the outer border of the frog skin (R. temporaria)

Abstract

Skins fromRana temporaria, investigated with microelectrode techniques in the absence of Na uptake across the outer border (Na-free epithelial solution or amiloride), were found to be permeable to K⁺ at the apical membrane in 10–20% of the experiments. Full development of the K⁺-permeable state requires the absence of Na⁺ uptake for certain periods of time, which suggests that the K⁺-permeability of the apical membrane is higher at lower intracellular [Na]. The addition of Ba⁺⁺ reduces the K⁺-permeability of the apical membrane. These skins may provide a model for the study of transcellular K⁺ movements.