The role of intestinal endotoxin in experimental peritonitis.

Escape of endotoxin from the intraintestinal site was investigated in experimental models of intestinal ischemia and during intraabdominal infection in rats. Following the instillation of Salmonella abortus equi endotoxin (S-form) into the proximal large bowel, we recorded the presence of the lipopolysaccharide molecule in the bowel wall, the intestinal lymph nodes, the peritoneal cavity, and in the liver sinusoids by immunohistochemical methods. At 3, 6, 12, 24, and 48 hr after the operative procedure, peritoneal fluid, blood, and tissue samples were taken. Survival rates were similar between the two test-groups (occlusion of the superior mesenteric artery [SMA] and cecal ligation and puncture [CLP]) and were not influenced by the amount of the injected endotoxin. There was no detectable morbidity in the sham-operated control animals with endotoxin doses up to 20 mg. Endotoxin could only be detected at 24 and 48 hr in the SMA group in the liver as well as in the peritoneal sediment and in intestinal lymph nodes. CLP and control samples remained negative throughout the observation period. Bacteria were found intraperitoneally within 12 to 24 hr in the SMA group and within 3 to 12 hr in the CLP group.