EFFECT OF AN ELEMENTAL VS A COMPLEX DIET ON L-CITRULLINE PRODUCTION FROM L-ARGININE IN RAT ISOLATED ENTEROCYTES

Background: L-Arginine and L-glutamine are highly metabolized by intes tinal cells, leading to various metabolites, including L-citrulline, w hich is required for optimal growth. Elemental diets, used in clinical practice to treat growth failure and malnutrition, are very different from complex diets normally consumed. The aim of the present study wa s to assess the effects of an elemental diet compared with a complex d iet on L-arginine metabolism in rat isolated enterocytes and its modul ation by L glutamine, Methods: Rats were fed the elemental diet (group ED) or the control diet (group C) for 14 days. Villus enterocytes the n were isolated, and metabolic capacities or enzyme activities were as sessed. Results: The incubation of enterocytes isolated from group C w ith 0.1 mmol/L L-[U-C-14]-arginine led to the production of 125 +/- 25 pmol L-citrulline/10(6) cells per 30 minutes. This production showed a twofold increase in the presence of 2 mmoL/L L-glutamine. In group E D, L-citrulline synthesis from L-arginine was markedly lower in the ab sence or in the presence of L-glutamine. This coincided with lower car bamoylphosphate synthase I activity and carbamoylphosphate (CP) conten t of enterocytes. Other L-arginine and L-glutamine metabolic pathways were not affected. Similar results were obtained when the elemental di et was administered continuously through a gastric catheter or fed by mouth. Conclusions: L-Glutamine favors the synthesis of L-citrulline f rom L-arginine in isolated enterocytes, probably via an increase in CP production. Changing the diet composition;from a complex to an elemen tal diet, results in an alteration of the enterocyte capacity to synth esize L-citrulline from L-arginine, irrespective of the rhythm of deli very.