Changes in body posture alter plasma nitrite but not nitrate concentration in humans

Liddle, Luke; Monaghan, Christopher; Burleigh, Mia C.; McIlvenna, Luke C.; Muggeridge, David J.; Easton, Chris

Abstract

PURPOSE: This study evaluated the change (Δ) in plasma volume (PV), nitrate [NO3-], and nitrite [NO2-] concentration following changes in posture in the presence and absence of elevated plasma [NO3-] and [NO2-] METHODS: Fourteen healthy participants completed two trials that were preceded by either supplementation with NO3--rich beetroot juice (BR; total of ∼31 mmol NO3-) or no supplementation (CON). Both trials comprised 30 min of lying supine followed by 2 min of standing, 2 min of sitting and 5 min of sub-maximal cycling. Measurements of plasma [NO3-] and [NO2-] were made by gas-phase chemiluminescence and ΔPV was estimated using the Dill and Costill method.

RESULTS: Plasma [NO2-] decreased from baseline (CON: 120 ± 49 nM, BR: 357 ± 129 nM) after lying supine for 30 min (CON 77 ± 30 nM; BR 231 ± 92 nM, both P < 0.01) before increasing during standing (CON 109 ± 42 nM; BR 297 ± 105 nM, both P < 0.01) and sitting (CON 131 ± 43 nM; BR 385 ± 125 nM, both P < 0.01). Plasma [NO2-] remained elevated following exercise only in CON (125 ± 61 nM P = 0.02). Plasma [NO3-] was not different between measurement points in either condition (P > 0.05). PV increased from baseline during the supine phase before decreasing upon standing, sitting, and exercise in both trials (all P

Citation

Liddle, L., Monaghan, C., Burleigh, M. C., McIlvenna, L. C., Muggeridge, D. J., & Easton, C. (2018). Changes in body posture alter plasma nitrite but not nitrate concentration in humans. Nitric Oxide: Biology and Chemistry, 72, 59-65. https://doi.org/10.1016/j.niox.2017.11.008

• Journal Article Type: Article
• Acceptance Date: Nov 28, 2017
• Online Publication Date: Dec 2, 2017
• Publication Date: 2018-01
• Deposit Date: Oct 22, 2020
• Publicly Available Date: Oct 23, 2020
• Journal: Nitric Oxide
• Print ISSN: 1089-8603
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 72
• Pages: 59-65
• DOI: https://doi.org/10.1016/j.niox.2017.11.008
• Keywords: Beetroot juice, Exercise, Plasma volume
• Public URL: http://researchrepository.napier.ac.uk/Output/2694105