NET FLUXES OF ELECTROLYTES IN THE RAT INTESTINE INFECTED WITH MONILIFORMIS-DUBIUS (ACANTHOCEPHALA)

The effect of Moniliformis dubius on fluxes of Na+, K+, Cl- and HCO3- in the rat intestine was determined using a conventional in vivo single-pass perfusion technique. Results for ion and H2O movements in the uninfected gut were in agreement with previous studies. In the parasitized intestine the jejunal pH was significantly lower than that in control animals, matching the restriction of the parasites to this region of the small intestine. While parasitism did not affect Na+ transport in the distal ileum, Na+ absorption was reduced (pH 7.0), or secretion enhanced (pH 6.0), in the 2 proximal regions. Cl- absorption was reduced in the distal ileum, but secretion was enhanced in the other 2 segments. Parasitism also enhanced K+ secretion in all segments. Net H2O absorption was reduced at pH 7.0; at pH 6.0 net secretion was also reduced. These changes clearly indicate that a parasite restricted to the jejunum may significantly affect the absorptive and secretory activity of the intestine distal to the site of infection. The results are discussed in the light of current concepts of electrolyte transport. The effect of the parasites on mucosal function distal to their site of attachment is discussed in terms of the release by the parasite of toxin-like substances, changes in the physical-chemical characteristics of the intestinal lumen and interference with neurohormonal control of gastrointestinal function.