BIDIRECTIONAL SMALL-INTESTINAL PERMEABILITY CHANGES TO DIFFERENT-SIZED MOLECULES AFTER HCL-INDUCED INJURY IN THE RAT

A rat model was developed to assess bidirectional passage of macromole cules and low-molecular-weight markers across the intestinal barrier i n intact and injured mucosa. Isolated in situ loops of distal small in testine were luminally perfused for 30 min with saline as control or H Cl (pH 2.0) to induce an acute injury. The lumen-to-blood passage was followed during perfusion with bovine serum albumin, [C-14]mannitol, a nd sodium fluorescein. Intravenously administered sodium fluorescein a nd endogenous serum albumin were used as blood-to-lumen markers. Acid exposure resulted in severe injury of the villi tips, with significant ly increased lumen-to-blood passage of all markers compared with that of intact mucosa. Moreover, blood-to-lumen passage of rat serum albumi n increased after the injury, while that of sodium fluorescein did not . The acid induced injury impaired the intestinal barrier function wit h an increased marker passage, where the macromolecules were more sens itive markers of the altered barrier function than low-molecular-weigh t markers.