Differences in jejunal and ileal response to E. coli enterotoxin: possible mechanisms.
Escherichia coli, which produce heat-stable enterotoxin (STa), cause intestinal fluid secretion as a mechanism of diarrhea. To determine the factors that modulate the intestinal secretory response, we first compared the time course of the STa-induced secretion in ligated in situ loops of rat jejunum and ileum. We found that the jejunal secretory response was brief (less than or equal to 30 min) while the ileal response to STa was sustained (greater than or equal to 3 h). We then compared the modification of purified STa that occurred in jejunum and ileum and found a close correlation between the continued presence of unmodified, authentic STa and continued fluid secretion in the ligated-loop model. At both sites alteration of STa was demonstrated by high-performance liquid chromatography profile and brush-border membrane binding activity. However, in the jejunum, the modification of STa was qualitatively different and quantitatively much greater. We conclude that the degree to which STa is inactivated or removed from the intestine correlates with the secretory response observed. Inactivation of STa may be a mechanism by which the host limits its secretory response.
Cohen
M B
MB
Division of Pediatric Gastroenterology, Children's Hospital Medical Center, Cincinnati 45229.
Thompson
M R
MR
Giannella
R A
RA
D000818:Animals; D000833:Animals, Suckling; D001427:Bacterial Toxins / Q000032:analysis / Q000494:pharmacology*; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D004768:Enterotoxins / Q000032:analysis / Q000494:pharmacology*; D029968:Escherichia coli Proteins; D007082:Ileum / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)