Comparison of the Effects of Enterotoxins of Shigella dysenteriae and Vibrio cholerae on the Adenylate Cyclase System of the Rabbit Intestine

Secretion of fluid by rabbit ileum and the relation of the secretion to intestinal adenylate cyclase, phosphodiesterase, and cyclic adenosine 3',5'-monophosphate (cyclic AMP) were compared in intestinal segments exposed to the enterotoxin of Shigella dysenteriae and / or the enterotoxin of Vibrio cholerae. Although there were some similarities in the gross appearance and kinetics of fluid secretion in-duced by the two toxins, the biochemical pathways appeared to differ. Shigella enterotoxin applied in vivo or to in vitro intestinal preparations did not produce the marked increase in adenylate cyclase or cyclic AMP noted after the application of V. cholerae enterotoxin. Moreover, despite known cytotoxic properties of shigella enterotoxin, prior treatment with this toxin did not prevent the intestine from responding to V. cholerae enterotoxin. An enterotoxin produced by Shigella dysenteriae type 1 has been recently isolated [1]. The toxin is able to elicit secretion of fluid in ligated seg-ments of rabbit ileum, and this secretion is sig