EXUDATIVE AND ABSORPTIVE PERMEABILITY IN DIFFERENT PHASES OF AN EXPERIMENTAL COLITIS CONDITION

Background: Increased intestinal 'permeability' in inflammatory bowel disease and in animal models of this disease has been reported. This s tudy asks if permeability changes are bidirectional and parallel cellu lar inflammation. Methods: In rats acute inflammatory cell infiltratio n (ICI) was induced in an excluded bowel loop by instillation of 4% ac etic acid. Plasma exudation was investigated by intravenous infusion o f I-125-albumin and determination of radioactivity in loop perfusates. Absorption was measured by placing Cr-51-ethylenediaminetetraacetic a cid in the loop and counting total radioactivity appearing in urine ov er 24 h. Results: Acute ICI was induced with acetic acid on day 4 but, as judged by ICI and histology, recovered by day 14. Acetic acid trea tment resulted in increased absorption on day 4, which returned to con trol levels by day 14. Acetic acid treatment resulted in increased pla sma exudation on day 4, which remained increased on day 14. Conclusion : Absorption and exudation changes are not necessarily bidirectional, and ICI may not be required for significant and sustained plasma exuda tion to take place. We suggest that the exudative response reflects a 'functional inflammation' that may occur and be important also in the absence of the traditional indices of bowel inflammation.