Colchicine effect on the permeability of the whole epithelium and of isolated cells of frog skin

The effect of 2×10^–5 M colchicine on epithelial cells isolated from frog skin was investigated. Three hours of treatment with colchicine did not change either Na⁺ and K⁺ content of isolated cells or nonelectrolyte permeability. When ADH (50 mU/ml) was added, thiourea uptake values became greater than without the hormone; the same values were found in the cells previously treated with colchicine. Na⁺ transepithelial transport, measured by means of short-circuit current, was inhibited by the antimitotic agent both under control conditions and after ADH stimulation. These results support the view that colchicine does not directly affect ADH action on membrane permeability, but influences some mechanism that controls ADH action on transepithelial transport. Intercellular junctions appear to be the location of such a mechanism.