Permeability of the rabbit colon in vitro

The rabbit colon, in vitro as everted-sac or diaphragm preparations, exhibits a transmural PD, as high as 70 mV, a short-circuit current (SCC) of 100 to 150 muA cm-3 and a resistance of 300-500 omega-cm2. It maintains these functions for at least 3 h. The SCC can be abolished by amiloride or increased by amphotericin B. Na, Cl, and K flux measurements showed a net influx (mucosa to serosa) of Na and a net efflux of K. The SCC can be accounted for by the movements of these ions. The SCC in the presence of amphotericin B was nearly equivalent to the net Na flux. Amiloride abolished the net Na transfer but did not ht (Ktrnas X 10(7)) for water was 5,000 cm s-1 while that for urea was 26 cm s-1. The rabbit provides a viable pn and the present observations appear to be consistent with its physiological role.