Comparison of the effects of disodium ethylenediaminetetraacetate, theophylline, and deoxycholic acid on colonic ion transport and permeability.

The effects of ethylenediaminetetraacetate (EDTA), theophylline, and deoxycholic acid (DCA) on colonic ion transport and permeability were examined in an isolated loop system of the pig colon. The 3 agents abolished net water absorption, but only EDTA and DCA induced an increase in mucosal permeability. Theophylline resulted in active bicarbonate secretion and increased the transmural electrical potential difference, whereas DCA resulted in a dose-dependent inhibition of the theophylline-stimulated potential difference and antagonized or abolished the effect of theophylline on ion transport. A similar inhibition of the sodium transport potential across the mucosa resulted with DCA. The effects of DCA on the potential difference were immediate and reversible and paralleled the changes in colonic permeability. These results are consistent with the hypothesis that the mechanism of bile acid-induced diarrhea is through an increase in mucosal permeability and/or mucosal damage. Evidence of an active secretory process was not demonstrable with this preparation.