The action of Cu2+ on the frog epithelium

The mechanism of action of Cu2+ when applied to the external side of the frog skin preparation was investigated. Cu2+ acts most probably on the external barrier of this preparation, since it increases the transport pool of Na proportionally to the increase in the short-circuit current (I(sc)). Cu2+ does not open new routes for the Na+ entry since the stimulated I(sc) is still completely abolished by amiloride. The I(sc) dependence of Na concentration in the external medium is modified by cooper, since the Ksm value increases in addition to changes in I(sc).