COLONIC WATER ABSORPTION IS IMPAIRED DURING SMALL INTESTINAL SECRETION DUE TO CHOLERA TOXIN (CT)

Abstract

The effects of CT on small intestinal transport of water and electrolytes are well characterized. However, it is not known whether ion and water transport are altered in the colon when CT is present only in the small intestine. Aiming at defining the role of the colon in handling of water and electrolyte transport in such circumstances, we have measured water and ion transport in vivo in rat jejunal and colonic separate loops. Two groups of rats were investigated: in one, CT (1 ug/ml) was instilled in the jejunal loop two hours before separate perfusion of both loops for the ensuing 3 hours with a modified Ringer solution; the other (control) was likewise handled, but without any previous instillation of CT. Results: In CT animals, water transport in the jejunum was significantly (p<0.01) shifted toward secretion (-0.77±2.0 ul/min g wet weight vs. 13.19±1.9 in the controls). Similarly, in CT animals, the simultaneously measured water transport to the colon was also significantly (p<0.01) shifted toward secretion (0.6±2,4 vs. 6.7±1.6 in the controls). Ha net transport paralleled these changes. In conclusion: our data shows that the colon contributes to the overall intestinal secretion seen in cholera infection, even when CT does not interact with its mucosa. It remains to be seen whether such observation relates only to CT-elicited small intestinal secretion or it represents a general pattern linking small and large intestinal transport.