Colonic water and ion transport under the influence of deoxycholic acid, theophylline and ethylenediaminetetraacetate in rats

Abstrakt

The experiments (in situ) on and isolated colonic loop in rats aimed at indicating the changes in the secretion/absorption of electrolytes and water under the influence of such factors as deoxycholic acid (DCA), theophyline (T) and EDTA, in various ways changing the transport mechanisms in colon. Temporary changes of water volume in the studied loop and ion movement were calculated after finding the marker concentration of PEG 4000). Contrary to the control solution, both DCA and T caused the secretion of water and electrolytes to the colon. Combining the two applied compounds decreased the secretive response of colon. After applying EDTA only a decrease of water absorption was observed instead of secretion. DCA caused increased excretion of Na⁺ and the greatest, of all the used substances, increase of Cl^- secretion, while T caused the greatest secretion of sodium, decreasing the secretion of chloride. On the other hand, EDTA caused a considerable increase of Na+ and a slight increase of Cl^-. The received secretive responses point out that the applied substances affect various transport processes in colon. The effect of EDTA results from its properties chelating Ca²⁺ ions inside the cells. It should be supposed that only non-conjugated bile acids, including DCA, increase the filtration to the colon beside the cells, giving rise of microscopic injuries of mucosa.