Bidirectional supply of glutamine maintains enterocyte ATP content in the in vitro Ussing chamber model

Glutamine is the principal energy source for enterocytes, but it is not kno wn whether parenteral or enteral supplementation is most beneficial to gut integrity. The aim of this study was to evaluate the effects of glutamine i n uni- or bidirectional supply on the viability of intestinal mucosa of sta rved rats during incubation in Ussing chambers. Segments of jejunum from ra ts starved for 48 h were randomly mounted in Ussing chambers with three nut rient solutions: Krebs buffer without glutamine; 6 mM glutamine added to th e mucosal side; 6 mM glutamine added to the mucosal side and 0.6 mM glutami ne to the serosal side. ATP content of the mucosa, electrophysiology, and C r-51-ethyl-enediaminetetraacetate (EDTA) permeability were studied during 1 80 min of incubation. The addition of glutamine to both sides of the stripp ed mucosa improved ATP levels compared to the Krebs solution (P<0.05), and the addition of glutamine resulted in an increase in short circuit current (P<0.05). No significant differences were seen in Cr-51-EDTA permeability o r epithelial electrical resistance. Glutamine supplementation to both the l uminal and serosal side in the Ussing chamber was more effective than lumin al glutamine only in maintaining ATP levels of intestinal mucosa. Bidirecti onal supplementation of glutamine might improve intestinal energy metabolis m and viability in in vitro studies.