Acute dietary nitrate does not reduce resting metabolic rate or oxidative stress marker 8-isoprostane in healthy males and females.

To investigate changes in resting metabolic rate and 8-isoprostane, an oxidative stress biomarker, following acute dietary nitrate supplementation in healthy males and females. In a randomised, double-blind, cross-over study, 10 males and seven females (age range 19-25 years) underwent protocol familiarisation (visit 1), baseline assessments (visits 2 and 4) and assessments following supplementation, placebo or 6.2 mmol nitrate, 2 hours prior to visits 3 and 5. Participants completed a 30-minute RMR test with visits 2 and 3 on consecutive days, separated by a week-long washout period concluding with visits 4 and 5 on consecutive days. Plasma nitrate/nitrite (NOx) significantly increased (p ≤ 0.05) following dietary nitrate consumption compared to baseline values. No significant effect on resting metabolism (p = 0.194) or 8-isoprostane (p = 0.660) was observed following dietary nitrate supplementation. Dietary nitrate increases NO bioavailability, but acute supplementation does not effect resting metabolism or 8-isoprostane in healthy males and females.

Comparison between cuff-based and radial tonometry exercise-induced central blood pressure.

PURPOSE: Non-invasive central blood pressure assessed during exercise may provide better cardiovascular prognostic than measurements taken at rest. Radial tonometry is the only technique validated to perform this type of assessment; however, it relies on the experience of the tester. Cuff-based devices have been developed to avoid operator dependency, although these systems have yet to be validated during exercise. The purpose of this study was to compare exercise-induced central blood pressure estimations between a cuff-based device and radial tonometry. METHODS: Twenty young healthy subjects were recruited to perform a three-workload steady-state exercise test at blood lactate levels of < 2, 2-4, and > 4 mmol/L, respectively. Central systolic and diastolic blood pressure (cSBP and cDBP, respectively), central pulse pressure (cPP), and augmentation index (AIx) were assessed at rest and during each workload with a cuff-based device and radial tonometry. Statistical analysis included Bland-Altman analysis for agreement between techniques. Agreement was considered when 95% of the data set for each central blood pressure parameter was within 1.96 standard deviations from the mean difference. Significance was considered at α = 0.05. RESULTS: Central blood pressure measurements with the cuff device were obtained only at rest and during low-intensity exercise. During low-intensity exercise, all measurements showed agreement between both devices (cSBP 95% CI [- 6.0 to 10.7], cDBP 95% CI [- 4.5 to 6.3], cPP 95% CI [- 4.7 to 8.3], and AIx (95% CI [- 20.1 to 22.2]). CONCLUSION: A cuff-based device can estimate central blood pressure at low-intensity exercise, without operator dependency, and showing agreement to radial tonometry.

Internal validation of an automated system for brachial and femoral flow mediated dilation.

BACKGROUND: Flow Mediated Dilation (FMD) has immense potential to become a clinical, non-invasive biomarker of endothelial function and nitric oxide bioavailability, which regulate vasomotor activity. Unfortunately, FMD analysis techniques could deviate significantly in different laboratories if a validation process is not involved. The purpose of this study was to provide validation to the assessment of FMD analysis in our laboratory and to standardize this process before reporting results of FMD. METHODS: Brachial and femoral arteries FMD were performed on 28 apparently healthy participants (15 male and 13 female, ages 18-35 years). For the intratester reliability study, nine subjects were asked to come to the lab for a second brachial FMD within 48 h. All FMD procedures were performed by the same investigator, while the FMD analyses were performed by 2 independent testers who were blind to each other's analyses. FMD analyses included baseline artery diameter measurements, peak artery diameter after 5 min of ischemia, and FMD. Analysis was completed via an automated edge detection system by both testers after training of the methodical process of analysis to minimize variability. Intratester and intertester reliability were determined by using coefficient of variation (CV) between first and second visit (intratester) and between results obtained by both testers (intertester). RESULTS: The intratester CVs for tester 1 and 2 were 3.28 and 2.62%, 3.74 and 3.27%, and 4.95 and 2.38% for brachial baseline artery diameter, brachial peak artery dilation, and brachial FMD, respectively. In the intertester CVs were 2.40, 3.16, and 3.37% for brachial baseline artery diameter, peak artery dilation, and FMD, respectively and 4.52, 5.50, and 3.46% for femoral baseline artery diameter, peak artery dilation, and FMD, respectively. CONCLUSION: All CVs were under or around 5%, confirming a strong reliability of the method. Our laboratory has shown that the FMD protocol is reproducible due to the significantly low coefficient of variation. This is one step closer to use FMD as a biomarker for endothelial function in our laboratory.