Transfer of sodium and water through isolated rat colonic mucosa under the influence of deoxycholate and oxyphenisatin.

1. The influence of oxyphenisatin (OP), a diphenolic laxative, and deoxycholate (DC) on the transfer of sodium and water in an everted sac preparation of stripped rat colon was investigated. 2. OP (10(-5) M, mucosal side) and DC (3 X 10(-4) M, mucosal side) completely blocked net water and sodium absorption. Net movements from the serosal to the mucosal side could not be induced by higher concentrations of the drugs. 3. Unidirectional sodium movements in both directions were increased by OP and DC. 4. The effect of DC on the sodium flux from the serosal to the mucosal side was reversible. 5. The potassium content of the mucosal epithelium was not changed by DC and OP. 6. The integrity of the epithelium, as judged by light microscopy, was not disturbed by either drug under the experimental conditions. 7. It is concluded that DC and OP do not interfere with active transport mechanisms but increase the permeability of the epithelium to sodium.