Arginine or citrulline associated with a statin stimulates nitric oxide production in bovine aortic endothelial cells.

Nitric oxide (NO) is an antiatherogenic vasodilator synthesized from arginine and, indirectly, from citrulline through argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL). Hypercholesterolemia-induced atherosclerosis is usually treated by statins, which decrease cholesterolemia and increase endothelial NO synthase (eNOS) activity. Therefore, a treatment associating a statin with arginine or citrulline could be more efficient than statin alone. The aim of this study was to optimize NO production in bovine aortic endothelial cells (BAEC) by a combination of simvastatin with arginine or citrulline and to identify the molecular mechanisms involved. NO production was measured after stimulation of BAEC in different conditions (simvastatin 0 to 10 µM associated with arginine or citrulline 0 to 5 mM) after 24-hour incubation. Intracellular levels of specific proteins were evaluated by Western-Blot analysis, and mRNA levels of eNOS, iNOS, caveolin-1, ASS and ASL were assessed by RT-PCR. Simvastatin co-administrated with arginine or citrulline increased NO production, but at simvastatin 10 µM, 1 mM arginine-induced NO production was significantly (P < 0.01) higher than 1 mM citrulline-induced NO production. Simvastatin induced an increase in eNOS mRNA expression and protein levels in the presence of arginine or citrulline. ASS and ASL mRNA levels were increased by simvastatin, whereas a high substrate concentration (1 mM) strongly decreased ASL mRNA levels. Combining statin with arginine or citrulline increased NO production in endothelial cells by increasing eNOS protein levels. These results form a strong rationale to evaluate the potential utilization of these in atherosclerosis prevention and treatment.

High plasma citrulline and arginine levels ensured by sustained-release citrulline supplementation in rats.

OBJECTIVE: Dietary-supplemented arginine has been shown to have positive effects on cardiovascular disease, but several drawbacks exist and could potentially be avoided by using L-citrulline, since it is recycled to L-arginine. However, citrulline is very rapidly metabolized. We therefore developed a sustained-release form of citrulline and evaluated its metabolic behavior in rats. METHODS: Male Sprague Dawley rats were divided into three groups: receiving "empty microcapsule" (control group), 1 g/kg/d immediate-release citrulline (IR citrulline group), or 1 g/kg/d sustained-release citrulline (SR citrulline group). Citrulline was given each day at 9 a.m. after blood samples for 9 d, and on day 10, blood samples were drawn every 4 h to study the decrease in plasma amino acid concentrations. RESULTS: SR citrulline led to a sustained increase in citrullinemia and argininemia compared to IR citrulline, and on day 6 argininemia was significantly (P < 0.01) higher with SR compared to IR citrulline. Moreover, argininemia was significantly higher in the SR citrulline group than in controls throughout the study and SR citrulline maintained high argininemia and citrullinemia, at least over 12 h. CONCLUSION: This experimental study provides a strong rationale for using this new formulation for atherosclerosis treatment.

Plasma citrulline concentration reflects enterocyte mass in children with short bowel syndrome.

Plasma citrulline was recently shown to reflect the residual functional enterocyte mass in various situations characterized by intestinal failure. However, few data are available in children with short bowel syndrome. The objective of this study was to assess the value of citrulline assays in this situation. Prospective plasma citrulline assays were performed in 31 children with short bowel syndrome. Median age was 16 mo (range, 1 mo to 15 y), and median follow-up was 14 mo (6-40 mo). The energy supplied by parenteral nutrition (PN), served to assess intestinal failure severity. Plasma citrulline at inclusion showed a positive correlation with residual short bowel length. Subsequent values correlated negatively with intestinal failure severity. Plasma citrulline increased over time during or after weaning from PN (from 15.8 +/- 11.5 microM to 19.3 +/- 3.8 microM) but remained stable and low in patients who continued to need PN (6.5 +/- 3.0 microM at inclusion and 7.7 +/- 6.0 microM at last follow-up). No weaned patients had a residual short bowel length less than 40 cm and plasma citrulline less than 11 microM. Our findings constitute the first evidence that serial plasma citrulline assays help to monitor residual small bowel adaptation in children.