Chronic Obstructive Pulmonary Disease (COPD) is characterized by chronic systemic hypoxia and low-grade inflammation as well as by an alteration of arginine (ARG) metabolism. As ARG is synthetized from circulating citrulline (CIT), an alteration of CIT homeostasis, particularly its production by ornithine transcarbamylase (OCT) in small intestine could be involved. We hypothesized that hypoxia +/- inflammation, classically associated to COPD, has effects on OCT regulation in enterocytes.