Penetration of Anions Through Frog Skin

¹ From the Biophysical Laboratory, Purdue University, Lafayette, Indiana and the Zoophysiological Laboratory, Isotope Division, Copenhagen, Denmark

A feedback amplifier-servomotor circuit is described for holding frog skins at short-circuit. Under conditions of zero potential difference across the skin, the rate of transfer of radioactive chloride and iodide ions have been compared. Chloride crosses the skin about 2.5 times as fast as iodide when both sides of the skin are bathed with Ringer's solution. Iodide appears to cross somewhat more rapidly if both sides of the skin are bathed with an iodide-Ringer's solution.