Acute Dietary Nitrate Supplementation Does Not Alter Sympathetic Vasoconstrictor Responsiveness At Rest And During Exercise.
Bibliographic record
Abstract
Dietary nitrate (NO3−) supplementation has been shown to reduce resting blood pressure. However, the mechanism(s) responsible for the reduction in blood pressure has not been identified. Dietary NO3− supplementation may increase nitric oxide (NO) bioavailability and NO has been shown to inhibit sympathetic vasoconstriction in resting and contracting skeletal muscle. Therefore, dietary NO3− supplementation may attenuate sympathetic vasoconstrictor responsiveness. PURPOSE: To investigate the hypothesis that acute dietary NO3− supplementation would attenuate sympathetic vasoconstrictor responsiveness at rest and during exercise. METHODS: In a double-blind randomized crossover design, 12 men (23±5 yrs.) performed a cold pressor test (CPT) at rest and during moderate- (30% WRmax) and heavy-intensity (60% WRmax) alternate-leg knee-extension exercise after consumption of NO3− rich beetroot juice (~12.9 mmol NO3−) or a NO3−-depleted placebo (~0.13 mmol NO3−). Venous blood was sampled before and 2.5 hours after the consumption of beet root juice for the measurement of total plasma [NO3−]. Beat-by-beat blood pressure was measured by Finometer. Leg blood flow (LBF) was measured via Doppler ultrasound and leg vascular conductance (LVC) was calculated. Sympathetic vasoconstrictor responsiveness was calculated as the percentage decrease in LVC in response to the CPT. RESULTS: Total plasma [NO3−] was greater (p<0.001) in the NO3− (285±120 μM) compared to the placebo (65±30 μM) condition. However, mean arterial blood pressure was not different (p>0.05) between NO3− and placebo conditions at rest (NO3−: 82±5 mmHg; Placebo: 84±7 mmHg) and during moderate- (NO3−: 98±7 mmHg; Placebo: 97±9 mmHg) and heavy- (NO3−: 110±5 mmHg; Placebo: 115±12 mmHg) intensity exercise. Sympathetic vasoconstrictor responsiveness was also not different (p>0.05) between nitrate and placebo conditions at rest (NO3−: -33±10 %; Placebo: -35±11 %) and during moderate- (NO3−: -17±9 %; Placebo: -20±10 %) and heavy- (NO3−: -12±9 %; Placebo: -11±9 %) intensity exercise. CONCLUSION: These data demonstrate that acute dietary nitrate supplementation Supported by NSERC, Canada
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".