P402 THE LEVEL OF NITROGEN SUPPLY MODULATES THE EXPRESSION OF ARGININE METABOLIZING ENZYMES IN CACO-2/TC7 INTESTINAL CELLS

Portal arginine (Arg) plays a key role in liver ureagenesis. Intestine ability to control Arg availability from the diet may depend on a modulation of arginase, glutaminase, ornithine aminotransferase (OAT), argininosuccinate lyase (ASL) and synthetase (ASS) expression, according to protein supply. The aim of this work was to study the influence of amino acid (AA) supply on the intestinal expression of these enzymes.Caco‐2/TC7 cells were exposed for 3 days to different media containing AA at 0 (0), 1 (1X), 2 (2X) or 4 (4X) fold plasma post‐prandial concentrations. Enzymes mRNA were quantified using real time PCR. 18S rRNA was used as an internal control. Results (mean ± SEM) were analyzed by linear regression.There was an inverse relationship between AA supply and glutaminase (p= 0,028), OAT (p= 0,035), ASS (p= 0,028) and arginase (p= 0,058) expressions.This study shows for the first time a direct effect of AA supply on transcriptional regulation of arginine metabolizing enzymes. Such a regulation would enable in situations of low protein supply to increase Arg catabolism and to decrease hepatic AA oxidation thus promoting nitrogen sparing.