DIFFERENTIAL-EFFECTS OF AN INFUSION OF ENDOTOXIN ON PROXIMAL AND DISTAL FELINE JEJUNAL PERMEABILITY

The effects of an intravenous infusion of endotoxin (750 mu g/kg) or a n equal volume of saline solution (control) on the proximal and distal jejunal permeability and blood flow were evaluated in cats. In 8 cats , proximal and distal jejunal segments were isolated and mucosal clear ance of Cr-51-ethylenediaminetetraacetic acid (EDTA) was measured. The mucosal clearance in the distal loop was not altered by endotoxin inf usion in 6 cats given endotoxin or 2 cats given saline solution. In 6 cats given endotoxin, the proximal jejunal segment exhibited a 10-fold increase in mucosal permeability. In contrast, mucosal clearance rema ined stable in the proximal jejunal loop in 2 cats infused with saline solution. In a second group of 13 cats (7 cats infused with endotoxin ; 6 cats infused with saline solution), blood flow to the proximal and distal segments was measured. Either endotoxin (n = 7) or saline solu tion (n = 6) did not significantly alter blood flow to the proximal an d distal jejunum in these experiments. Samples of proximal and distal jejunum were collected from 12 cats (6 cats infused with endotoxin and 6 cats infused with saline solution). There was significantly more ep ithelial necrosis in the endotoxin treated cats than in the saline tre ated cats. Neutrophil infiltration was greater in the jejunal segments of endotoxin treated cats than in the jejunal segments of saline trea ted cats. In the endotoxin treated cats, there was significantly great er necrosis in the proximal jejunal segment than in the distal jejunal segment. There were no significant differences in numbers of neutroph ils in the proximal and distal jejunal segments. These results demonst rate that the proximal jejunum is more sensitive to endotoxin-induced increases in mucosal permeability than is the distal jejunum. The incr eases in mucosal permeability in the proximal jejunum were not accompa nied by significant reductions in jejunal arterial blood flow. Endotox emia induced neutrophil infiltration to the proximal and distal jejunu m.