ALANYL-GLUTAMINE DIPEPTIDE-SUPPLEMENTED PARENTERAL-NUTRITION IMPROVESINTESTINAL METABOLISM AND PREVENTS INCREASED PERMEABILITY IN RATS

Objective The authors determined the effects of alanyl-glutamine-suppl emented total parenteral nutrition (TPN) on mucosal metabolism, integr ity, and permeability of the small intestine in rats. Methods Male Spr ague-Dawley rats were randomized to receive TPN supplemented with a co nventional amino acids mixture (STD group) or the same solution supple mented with alanyl-glutamine; both solutions were isocaloric and isoni trogenous. On the seventh day of TPN, D-xylose and fluorescein isothio cyanate (FITC)-dextran were administered orally. One hour later, super ior mesenteric vein (SMV) D-xylose and plasma FITC-dextran concentrati on were measured. Intestinal blood flow and calculated intestinal subs trates flux were measured with ultrasonic transit time flowmetery. Res ults Plasma FITC-dextran increased significantly in the STD group. Int estinal blood flow and SMV D-xylose concentration did not differ betwe en the groups. Mucosal weight, villus height, mucosal wall thickness, mucosal protein, and DNA and RNA content in jejunal mucosa were signif icantly increased in the alanyl-glutamine group. Jejunal mucosal gluta minase activity and net intestinal uptake of glutamine (glutamine flux ) were significantly higher in the alanyl-glutamine group as compared with the STD group. Conclusion Addition of alanyl-glutamine dipeptide to the TPN solution improves intestinal glutamine metabolism and preve nts mucosal atrophy and deterioration of permeability.