The purpose of this study is to compare the metabolic fate of two oral forms of L-Arginine in healthy subjects featuring metabolic syndrome related risk factors
The study is a randomized crossover study including 16 healthy subjects with risk factors for metabolic syndrome and 16 healthy control subjects. According a double crossover design, each subject received two oral forms of L-arginine (A and B) in random order, and participated in a exploration day on the first day of arginine administration and after one week of supplementation with this arginine form. The two weeks of arginine supplementation were separated by a washout period of 2 weeks at least. Each exploration extended over 24 hours after administration of the first arginine dose. Blood tests were performed at 0, 0.5, 1, 2, 4, 6, 8, 12, 16, 24 h after administration of the first dose. During explorations after the supplementation period, we also collected urine (0, 2, 4, 8, 12, 24 h after the first dose).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Masking
SINGLE
Enrollment
32
3 capsules containing 0.5g of A form of L-arginine (1.5g) 3 times daily (4.5g per day) for 1 week
3 capsules containing 0.5g of B form of L-arginine (1.5g) 3 times daily (4.5g per day) for 1 week
Centre de Recherche sur Volontaires (CRV), Hospital Avicenne
Bobigny, Île-de-France Region, France
Estimate of total conversion of a dose of oral arginine into NO
This assessment uses labelled arginine (\[15N2-(guanido)\]-arginine) for the first dose of arginine taken in the morning, and measurements of 15NO3 in urine for 24h. After administration of 15N-arginine, for each urine collection, we determined the nitrate excretion (from measurement of diuresis and nitrate concentration, by reactive chemiluminescence) and isotope 15N enrichment of nitrate ion (by microdiffusion technique and elementary analyzer connected to an isotope mass spectrometerEA-IRMS), to establish, by the principle of isotopic dilution, the total quantities of nitrate specifically from the ingested arginine. The sum of this excretion relative to the ingested dose determined the relative conversion of ingested arginine into NO.
Time frame: Repeated measurement for 24h before (day 0) and after supplementation (day 8) for each treatment
Estimate of kinetic profiles of plasma arginine concentrations over 24 hours
Plasma AA concentrations were determined using an ultra-performance liquid chromatography-mass spectrometry system as previously described (Haque and al., 2012).
Time frame: Repeated measurement for 24h before (day 0) and after supplementation (day 8) for each treatment
Quantitative analysis of plasma markers of endothelial function
Fasting plasma concentrations of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule (ICAM-1), E-Selectin, P-Selectin, Plasminogen activator inhibitor-1 (PAI-1), will be determined using two custom mixed assay kits with antibody-coated beads using the Luminex xMAP technology platform for multiplexing of immunochemical bioassays. In addition, we also have plasma concentrations of nitrite, a marker of of NO production (by reactive chemiluminescence) and other associated markers (3-nitrotyrosine, nitrosothiols, cGMP, in particular ANP, by immunochemistry).
Time frame: Before supplementation (day 0) and after supplementation (day 8) for each treatment
Estimate of kinetics use of arginine for NO and urea synthesis
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After administration of 15N-arginine, we measured 15N isotopic enrichment of arginine and citrulline (by mass spectrometry coupled with gas chromatography), of plasma and urinary urea (by separation, by ion exchange, and EA-IRMS) as well as the plasma and urine concentrations in urea. These data and those of arginine and citrulline concentrations provided, by the principle of isotopic dilution, the plasma appearance of ingested arginine and the plasma appearance and urinary excretion of products of its metabolism in NO synthase and arginase ways. These data were then subjected to a compartmental modeling work to establish the metabolic flow in these ways.
Time frame: Repeated measurement for 24h after supplementation (day 8) for each treament
Other quantitative analysis
* Fasting Asymmetric Dimethyl-L-Arginine (ADMA) concentrations were measured by an enzyme-linked immunosorbent assay. * The fasting lipid profile (triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol) was measured and were assayed using "classical clinical biochemical analyzers". * The fasting insulin and glucose were assayed using "classical clinical biochemical analyzers". * Fasting metabolomic analysis
Time frame: Before supplementation (day 0) and after supplementation (day 8) for each treatment