THE INFLUENCE OF CIRCULATORY AND GUT LUMINAL CHALLENGES ON BIDIRECTIONAL INTESTINAL BARRIER PERMEABILITY IN RATS

Background: The endothelial and epithelial barriers are important for maintenance of intestinal barrier function. The present study evaluate d the response of these barriers after various challenges. Methods: Mu cosal endothelial and epithelial barrier integrity was evaluated by th e leakage of human serum albumin, labeled with different isotopes, fro m the circulation to the interstitium and the intestinal lumen, or fro m the intestinal lumen to the interstitium and the circulation, in rat s with endothelial or epithelial challenge. Results: Epithelial barrie r dysfunction and alterations in epithelial microvillous ultrastructur e showed a pattern dependent on the dose of the intraluminal detergent s, whereas only higher doses induced an increase in endothelial barrie r permeability. intravenous challenge with CHAPS or Triton caused a do se-dependent increase in both endothelial and epithelial barrier perme ability. The development of endothelial barrier dysfunction was relate d to a decrease in blood pH values. Conclusions: The results indicate that capillary endothelial barrier integrity may play an important rol e in maintaining intestinal barrier function and that endothelial inju ry may initiate or at least be involved in the development of intestin al barrier failure.