ROLE OF PROSTAGLANDINS AND ENTERIC NERVES IN ESCHERICHIA-COLI HEAT-STABLE ENTEROTOXIN (STA)-INDUCED INTESTINAL SECRETION IN PIGS

Objective-To examine the role of prostaglandins and enteric nerves in mediating intestinal secretion induced by enterotoxigenic Escherichia coil heat-stable enterotoxin (STa) in pig jejunum and distal portion o f the colon. Animals-Two- to 3-week-old suckling crossbred pigs were s tudied. Design-Changes in ion transport in response to mucosal additio n of E coli STa to jejunal and colonic tissues were studied in the pre sence and absence of inhibitors. Procedure-Flat sheets of muscle-strip ped proximal portions of the jejunum and distal portions of the colon were mounted in Ussing chambers equipped to measure changes in short-c ircuit current (Isc), a measure of active ion transport. Tissues were exposed to 200 ng of STa/ml administered to mucosal solutions, and sub sequent changes in Isc were recorded. Results-In control tissues, chan ges in Ise induced by STa in the distal colon were significantly great er (21.4 +/- 4 mu A/cm(2)) than those observed in the jejunum (14.0 +/ - 2 mu A/cm(2)). When either segment was exposed to the neurotoxin, te trodotoxin, or to the nitric oxide synthase inhibitor, N-G-nitro-L-arg inine-methyl ester, Isc responses to STa were unchanged, suggesting no involvement of submucosal nerves in mediating STa-induced secretion. When tissues from the distal portion of the colon and jejunum were pre treated with piroxicam, a prostaglandin synthesis inhibitor, the STa-i nduced Isc response was significantly reduced by 52 and 57%, respectiv ely. Conclusions-These results indicate that the pig jejunum and dista l portion of the colon are sensitive to the secretory actions of enter otoxigenic E coli STa, and that the responses are mediated, in part, b y release of prostaglandins.