Effects of Oral Citrulline on Protein Metabolism in Patients With Intestinal Failure (Citrugrêle 2)

After receiving a 7-day oral supplementation with either citrulline or placebo, each subject will be admitted for a half day, after an overnight fast, and will receive a 5-h intravenous infusion of L-\[1-13C\]leucine. At regular intervals throughout the isotope infusion, blood will be obtained to measure 13C-enrichment in plasma a-keto-isocaproate, using gas chromatography-mass spectrometry. Simultaneously, 13C-enrichment will be measured in aliquots of expired air CO2 using isotope ratio mass spectrometry, and total CO2 production (VCO2) will be measured using direct calorimetry, respectively. Then the subject take no treatment for 13 days. The study will then be repeated a second time in an identical fashion, after a second 7-day period of oral supplementation with either citrulline or placebo.