Effect of dietary control on plasma nitrate level and estimation of basal systemic nitric oxide production rate in humans

Abstract

It is of great interest and value to evaluate the systemic nitric oxide (NO) production rate in humans under various conditions. However, the currently available estimation methods are troublesome and time-consuming. We thus aimed at developing a simple method to estimate the basal systemic NO production rate in humans based on a steady-state analysis, i.e., a balance between the systemic NO production rate and the total nitrate elimination rate. Plasma nitrate concentrations of young healthy volunteers (n = 7 in group 1: n = 9 in group 2) were measured for 2 days. In group 1, all subjects had the same meals for 7 days prior to the plasma nitrate measurement. In group 2, all subjects were allowed free diets. The plasma nitrate concentrations were highly influenced by dietary nitrite/nitrate intake in both groups and reached the steady-state levels after 14-h fasting. Accordingly, the basal systemic NO production rates were estimated from the plasma nitrate concentrations after 14-h fasting (group 1, 630 +/- 37 nmol min(-1) = 0.78 +/- 0.03 micromol kg(-1) h(-1); group 2, 597 +/- 45 nmol min(-1) = 0.66 +/- 0.05 micromol kg(-1) h(-1), P = not significant vs group 1). These estimated values were comparable to the values obtained by other methods. In conclusion, the present estimation method with 14-h fasting using a single-compartment analysis was found to be a simple approach to quantitative evaluation and intra- and interindividual comparisons of the basal systemic NO production rates in humans.

New Methods to Evaluate Endothelial Function: A Search for a Marker of Nitric Oxide (NO) In Vivo: Re-evaluation of NOx in Plasma and Red Blood Cells and a Trial to Detect Nitrosothiols

“…According to the equation, we determined a NOx formation rate of about 0.5 m mol / kg × h, in concordance with values of NO formation estimated in anesthetized and awake rats (0.33 -0.85 m mol / kg × h) using isotopelabeled oxygen (41), in humans (0.38 -0.96 m mol / kg × h) using isotope-labeled oxygen (42) or arginine (43), or by theoretical analysis without isotope-labeled substrate (44). It should be noted that the NOx formation rate does not necessarily reflect NO formation directly in vivo; however, it would be acceptable as an alternative measure when the real NO formation rate is hard to evaluate.…”

Simvastatin Prevents Vascular Hyporeactivity During Inflammation

“…Controversial reports exist about expression of the inducible nitric oxide synthase isoform (iNOS) and statins. No change was reported after simvastatin, 3,43 whereas other studies demonstrated an inhibitory effect of atorvastatin. 44 However, the role of iNOS in the human LPS model is probably very limited, because our previous trial failed to demonstrate increased iNOS mRNA and protein expression after LPS.…”

“…13 The measurement of NOx levels in the present study was an attempt to detect changes in NO metabolism. Although no changes were observed in NOx levels, the results of these measurements are limited, because nitrate/ nitrite intake, which is known to influence NOx levels, 43 was not standardized during the study period.…”

Pulmonary and Systemic Nitric Oxide Measurements During CCK-5-Induced Panic Attacks

“…Subjects followed a nitrate/nitrite restricted diet (Wang et al, 1997) for 3 days before the test and fasted overnight (12 h) (Mochizuki et al, 2000). At 45 min before injection, an intravenous catheter was inserted into the antecubital vein for drug infusion and blood collection.…”