ELECTROPHYSIOLOGICAL AND TRANSPORTPHYSIOLOGICAL CHANGES IN PIG PROXIMAL COLON DURING PARASITIC INFECTION

Oesophagostomum dentatum, one of the most common nematodes in pigs, ca uses the formation of subepithelial granuloma in the large intestine. To investigate possible changes in epithelial function or response dur ing the infection we incubated epithelia of pig proximal colon in Ussi ng chambers at different days post infectionem (p.i.). Transepithelial conductance, g(t), and the Cl flux from serosal to mucosal, J(sm)(Cl) , were increased on day 2 p.i., when the nematodes penetrate the epith elium of the large intestine, and declined toward control levels there after. Histamine, PGE(2) and carbachol caused transient increases in s hort circuit current, I-sc, and conductance that could partly be attri buted to a higher J(sm)(Cl). The I-sc responses were highest on the da ys 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 parasi te and could be responsible for the absence of marked clinical signs d uring the infection. (C) 1997 Elsevier Science Inc.