Edge damage effect in in vitro frog skin preparations

Abstract

When frog skin is mounted between conventional chambers, some of the tissue in the exposed area is damaged by stresses imposed by the clamping process. It was possible to measure the extent and* characteristics of this damaged region by systematically altering the edge to surface ratio in chambers of special design. In the damaged area, extending about 0.7 mm from the clamped edge, intercellular spaces are enlarged and passive ion conductivity is increased, accounting for the drop in transmural electrical potential difference observed in small chambers. Short-circuit current is not affected. A method for estimating the series resistance, shunt resistance, and "sodium battery" potential from electrical measurements is described, which, combined with the variation of edge-to-surface ratio makes possible the estimation of the intercellular and intracellular shunt resistances.