GLUTAMINE DEPRIVATION IN RAT INTESTINAL CELLS. 476

Abstract

Our objective is to establish the importance of both endogenous and exogenous sources of glutamine (GLN) for proliferation and differentiation of small intestinal epithelium. We hypothesize that exposure to sub-physiologic concentrations of GLN (<0.4 mM) in cell culture media (exogenous GLN source) results in upregulation of glutamine synthetase (GS) activity(endogenous GLN source). Increased GS activity should compensate for the lack of exogenous GLN and result in no differences in variables indicative of cell growth. IEC-6 cells were grown in GLN-free DMEM containing 10% FBS. Confluent stock cultures were trypsinized and seeded (1 × 105 cells/well) onto plates grown in media containing 1 of 6 different concentrations of supplemental GLN (4, 2, 0.4, 0.2, 0.02, and 0 mM). The approximate percentage of area covered by cells, an indicator of cell growth, was monitored each day and time to confluency was noted. Cells were trypsinized and processed for determination of protein concentration, GS activity (μ M•mg-1protein•h-1), and 3H-thymidine incorporation (dp m•mg protein-1). Results (means± SD, *p<0.05): All variables decreased in response to decreased [GLN] in a dose-dependent manner. Table