The intracellular electrical potential profile of the frog skin epithelium.

The potential profile of the frog skin epithelium incubated in Cl-Ringer was reinvestigated with improved technique. Under open circuit conditions (PDtr up to 120 mV) the potential profile was demonstrated to be trough like in contrast to the stair-step like potential profile reported by previous investigators which has probably been recorded after injuring of the punctured cells. In 67 successful impalements the potential difference across the basolateral membranes was 108 +/- 2 mV. The potential across the outer, epithelial-facing membrane was inversely related to the transepithelial PD, but was found to be negative (with respect to the epithelial bathing solution) in all punctures. Electrogenic sodium transport might be responsible for part of the potential difference across the basolateral membranes which correlatee directly with the short circuited state was -73 +/- i mV and decreased with increasing short cirucit current. It is suggested that these changes result from variations of the outer membrane sodium conductance.