Chloride transport in isolated frog (Rana temporaria) skin

Summary In a large number of isolated frog skins, with potential differences of from 20–92mV (mean, 55.3±3.6 S.E.M.), the chloride influx was found to be slightly greater than chloride efflux under shortcircuit conditions, but the difference was not statistically significant. However, if skins of low potential (less than 50 mV) were selected, chloride influx was significantly higher than chloride efflux (P<0.05). In this low potential group furosemide, (10^–3 M, applied to the solution bathing the mucosal surface) was found to produce a) a small increase in short-circuit current, which was generally apparent within 1 min, maximal in 5 min; and thereafter declined towards the control value; b) a marked increase in potential difference, apparent within 1 min and sustained for at least 30 min; c) a large and sustained increase in the calculated d.c. resistance of the skin and d) a decrease in the influx of chloride, such that influx and efflux were equalized.