Effect of cloned Salmonella typhimurium enterotoxin on rabbit intestinal motility

We analysed the small intestine myoelectric responses of anesthetized New Zealand albino rabbits to Escherichia coli lysates containing an enterotoxin cloned from Salmonella typhimurium. Migrating action potential complex, which consisted of rapid bursts of action potentials and secretion of fluid, was observed only in ileal loops injected with the enterotoxin-containing lysate. Migrating action potential complex produced by Stn usually propagated aborally, which was typical of cholera toxin, but orad or bidirectional propagation occurred from a single point of origin when activity was intense. Gell lysates from an E. coli clone containing vectors alone, as well as proximal control segments injected with phosphate-buffered saline, gave neither a change in motility nor fluid secretion. These results show that Stn caused dramatic changes in intestinal motility and substantial fluid production.