Interrelationships between glutamine and citrulline metabolism

Abstract

Purpose of review To analyze the evidence that glutamine supplementation increases citrulline production. To determine the contribution of glutamine to the synthesis of citrulline. Recent findings Glutamine supplementation has been proposed in the treatment of critically ill patients; however, a recent large multicenter randomized controlled trial resulted in increased mortality in the glutamine supplemented group. Within this context, defining the contribution of glutamine to the production of citrulline, and thus to de novo arginine synthesis, has become a pressing issue. Summary The beneficial effects of glutamine supplementation may be partially mediated by the effects of glutamine on citrulline synthesis by the gut and the de novo synthesis of arginine by the kidney and other tissues. Although there is no strong evidence to support that glutamine is a major precursor for citrulline synthesis in humans, glutamine has the potential to increase overall gut function and in this way increase citrulline production.

Nutritional therapy complications in children with ultra‐short bowel syndrome include growth deficiency but not cholestasis

“…Citrulline is an amino acid that is mainly produced by enterocytes of the small bowel from glutamine‐derived from intestinal lumen and smaller amounts come from the blood supply . It plays a significant role in detoxification of ammonia and the production of urea, because citrulline is converted in the kidney to arginine, but it is also a potent factor in producing nitric oxide . In clinical studies, both the chronic and acute reductions of enterocyte mass have been correlated with low plasma citrulline concentration .…”

Intravenous citrulline generation test to assess intestinal function in intensive care unit patients

“…As documented earlier in the proof of principle study on CGT,8 the slope of the line between the baseline plasma citrulline concentration and peak plasma citrulline level during the CGT was calculated, reflecting the ability of citrulline generation from administered glutamine by the enterocytes. Then, the incremental area under the CGT curve was measured from 0 to 90 min (iAUCT90; incremental area under the plasma citrulline concentration vs time curve) 10…”

“…Since the small bowel is by far the largest source of circulating citrulline, this amino acid is thought to be a suitable biomarker of enterocyte function 6. Recently, this mechanism has been questioned based on tracer studies in which the carbon skeleton of glutamine and not the amino nitrogen was followed 7,8. It has been proposed that citrulline might be generated by various pathways; however, an overdose of glutamine initiates a maximal generation of citrulline in a skewed bell-shaped curve.…”

Biochemical Blood Parameters of Students in the Pre-Exam Period of Study

“…Один із важливих регуляторів проміжного обміну в організміамінокислота цитрулінпотужний антиоксидант, особливо виражена його активність щодо нейтралізації гідроксильних радикалів. Нирки є основним органом, де відбувається метаболізм цитруліну, визначення його рівня в крові може бути використано як специфічний біохімічний маркер для оцінки функціонального стану проксимальних канальців нирок, ступеня пошкодження нирок і наявності ниркової недостатності за різних патологічних станів [16,17]. Вміст цитруліну достовірно не змінювався у осіб дослідної групи порівняно з контрольною групою, хоча існує певна тенденція до зростання.…”