Inhibition of potassium conductance by barium in frog skin epithelium

The effect of Ba2+ (0.5 mM, corial side) upon the transport characteristics of the frog skin epithelium was investigated. It was observed that Ba2+ decreased the conductance of the preferably K+-permeable basolateral border to less than 30% of its control value. Furthermore, Ba2+ abolished the K+ electrode-like behaviour, existing at the basolateral membrane under conditions of zero transcellular current flow, for [K+] below 10--15 mM. Effects upon other parameters of transepithelial transport (electromotive forces and resistance of outer or basolateral border and shunt pathway, respectively) were small and might represent secondary events. It is concluded that Ba2+ inhibits passive fluxes of K+ across basolateral membranes of tight, Na+ transporting epithelia, similar to its influence upon membranes of nonpolar cells.