title: Activation of Heat-labile Escherichia coli enterotoxin by trypsin.
abstract: Trypsin-treated, cell-free filtrates derived from enterotoxigenic Escherichia coli, strain H197 (O78:H11), exhibited a fourfold or greater increase in heat-labile vascular permeability factor activity and a 10-fold or greater increase in the ability to stimulate secretion of growth hormone by cultured rat pituitary cells. In contrast, trypsin-treated filtrates were not different from untreated filtrates in their ability to elicit a secretory response in ligated rabbit intestinal loops. However, incubation of culture filtrate in ligated intestinal loops, or with rabbit intestinal fluid (in vitro), resulted in at least a twofold increase in permeability factor that did not occur in the presence of trypsin inhibitor or with heat-inactivated intestinal fluid. Moreover, trypsin inhibitor could reduce the secretory response to culture filtrate. These findings suggest that activation of heat-labile E. coli enterotoxin by host enzymes may play a role in the development of a full pathogenic effect.
mesh_terms: D000818:Animals; D000992:Antitoxins / Q000494:pharmacology; D002199:Capillary Permeability; D004926:Escherichia coli; D005732:Gangliosides / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism; D006358:Hot Temperature; D007082:Ileum / Q000378:metabolism; D066298:In Vitro Techniques; D007419:Intestinal Secretions / Q000201:enzymology; D010902:Pituitary Gland / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D014357:Trypsin / Q000494:pharmacology*; D014361:Trypsin Inhibitors / Q000494:pharmacology; D014734:Vibrio cholerae
chemical_list: D000992:Antitoxins; D005732:Gangliosides; D014361:Trypsin Inhibitors; D013006:Growth Hormone; D014357:Trypsin