Effect of deoxycholate on the perfused rat colon. Concentration dependence of the effect on net fluid and electrolyte transfer and the correlation with paracellular permeability.

We reexamined the question whether the deoxycholate-evoked alteration of net transfer of fluid and electrolytes is primarily caused by active secretion or paracellular filtration. In the in vivo perfused rat colon, deoxycholate caused a dose-related increase in 51Cr-EDTA clearance proportional to the rate of fluid, sodium, and chloride secretion. These increases of fluid production and epithelial permeability were reversible and showed the same time dependence. Potassium, however, was already maximally secreted at the lowest deoxycholate concentration (1 mmol/l). This study supports the hypothesis that the secretion of fluid in the deoxycholate-treated colon is quantitatively determined by the increase of the paracellular permeability.