Abstract
The distribution of fluorescein isothiocyanate dextran 70,000 (FITC-dextran) and mucous gel across the lumen of small intestine was observed as an investigation into the role of mucous gel on permeability in total parenteral nutrition (TPN). Thirty-two rats were randomly divided into two groups fed with either TPN or oral rat food. On day 4 or 7, FITC-dextran (750 mg/kg body weight) was given through the gastroduodenal tube. After 1 hour, blood samples were taken by aortic puncture to analyze plasma FITC-dextran by fluorescence spectrometry. Samples of small intestine with luminal contents were frozen and sectioned in a cryostat for fluorescence microscopy; the same sections were placed in a 0.2% celloidin solution for 3 minutes to preserve mucous gel and stained by periodic acid-Schiff reaction for light microscopy. The plasma level of FITC-dextran after 1 hour of this marker injection showed a significant increase (p < .01) in the TPN group compared with the rat food group on days 4 and 7. Morphologic findings on days 4 and 7 were similar in both the jejunum and ileum: The mucous gel filled the spaces between villi and FITC-dextran centered in the lumen in the rat food group, whereas the mucous gel decreased and FITC-dextran filled the spaces between villi in the TPN group. FITC-dextran and mucous gel showed complementary distributions in both groups. These data suggest that TPN decreases luminal mucous gel and increases permeability of small intestine in rats. (Journal of Parenteral and Enteral Nutrition 18:346–350, 1994)
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