Aspects of Bacterial Enterotoxins Other than Cholera on Intestinal Permeability

Abstract

Cholera enterotoxin (CT) (Holmgren and Lonnroth 1980) has been the major stimulus for studies of other bacterial enterotoxins. Its features are well described in Chap. 26. Studies of the labile toxin (LT) of Escherichia coli (Field 1974), demonstrating that its mode of action is very similar to that of CT, and recent studies of the stable toxin (ST) of E. coli (Field et al. 1978; Staples et al. 1980) which have demonstrated that ST specifically activates guanylate cyclase in intestinal mucosal cells, have been the major recent developments in studies of other bacterial enterotoxins. Many enterotoxins have been identified, but have either not been as fully purified as E. coli LT and ST or their mode of action on transport processes is less well defined. Information as to their role or significance in bacterial diarrheal disease processes is also limited. Definition of their specific mode of action will, however, be of importance for several reasons, (a) They may help to define normal intestinal physiologic processes in a manner similar to that demonstrated by CT-activated chloride secretion, (b) Other bacterial toxins may cause fluid and electrolyte secretion by activation of secretory processes distinct from those dependent on activation of the cAMP or cGMP systems; for instance, no toxins have yet been identified to cause secretion by mechanisms similar to those accompanying serotonin-induced intestinal secretion and there is no clear knowledge of whether filtrative secretion is a factor in a toxin-mediated process.