Electro- and transportphysiological changes in pig proximal colon during parasitic infection

Oesophagostomum dentatum, one of the most common nematodes in pigs, causes the formation of subepithelial granuloma in the large intestine. To investigate possible changes in epithelial function or response during the infection we incubated epithelia of pig proximal colon in Ussing chambers at different days post infectionem (p.i.). Transepithelial conductance, gt, and the Cl flux from serosal to mucosal, JsmCl, were increased on day 2 p.i., when the nematodes penetrate the epithelium of the large intestine, and declined toward control levels thereafter. Histamine, PGE2 and carbachol caused transient increases in short circuit current, Isc, and conductance that could partly be attributed to a higher JsmCl. The Isc responses were highest on the days of nematode penetration in or out of the epithelium (days 2 and 14 p.i.) and did decline on day 7 p.i. during the histotropic development of the parasite. This reduced epithelial reaction on day 7 p.i. might be an adaptation to secretory stimuli released from the inflammatory cells in the intestinal wall or might reflect modulation by the parasite and could be responsible for the absence of marked clinical signs during the infection.