Pathway of sodium moving from blood to intestinal lumen under the influence of oxyphenisatin and deoxycholate.

The transfer of (51)CrEDTA and inulin--substances which are distributed only in the extracellular space--across the rat colonic mucosa in vivo is increased by oxyphenisatin O (3.5 times 10(-5)M) and deoxycholate D(3 times 10(-3)M). O and D do not change the size of the intra- and extracellular fluid compartments of the mucosa as measured with (51)CrEDTA from the blood side. The sodium and potassium content of the mucosal tissue is not altered. Therefore the calculated intracellular concentrations of sodium and potassium remain constant. The time course of the (22)Na uptake into the mucosal epithelium is not influenced by O and D up to 5 min after i.v. injection. The specific activity of sodium, however, in the luminal fluid increases under the influence of O(twofold) and D(fivefold). The uptake of (22)Na into the mucosal tissue after administration of (22)Nainto the intestinal lumen is not changed in presence of O and D. We conclude that the net transport of sodium and water from blood to lumen under the influence of O and D occurs mainly via the intercellular way.