The effects of two different doses of ultraviolet-A light exposure on nitric oxide metabolites and cardiorespiratory outcomes

Christopher Monaghan, Luke C McIlvenna, Luke Liddle, Mia Burleigh, Richard B. Weller, Bernadette O Fernandez, Martin Feelisch, David J. Muggeridge, Chris Easton

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2 Citations (Scopus)
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Abstract

Purpose: The present study investigated different doses of ultraviolet-A (UV-A) light on plasma nitric oxide metabolites and cardiorespiratory variables.
Methods: Ten healthy male participants completed three experimental conditions, 7 days apart. Participants were exposed to no light (CON); 10 J•cm2 (15 min) of UV-A light (UVA10) and 20 J•cm2 (30 min) of UV-A light (UVA20) in a randomized order. Plasma nitrite [NO2-] and nitrate [NO3-] concentrations, blood pressure (BP), and heart rate (HR) were recorded before, immediately after exposure and 30 min post-exposure. Whole-body oxygen utilization (V̇O2) and skin temperature were recorded continuously. 
 Results: None of the measured parameters changed significantly during CON (all P>0.05). V̇O2 was significantly reduced immediately after UVA10 (P=0.03) despite no change in plasma [NO2-] (P>0.05). Immediately after exposure to UVA20, plasma [NO2-] was higher (P=0.014) and V̇O2 tended to be lower compared to baseline (P=0.06). There were no differences in [NO2-] or V̇O2 at the 30 min time-point in any condition. UV-A exposure did not alter systolic BP (SBP), diastolic BP or MAP (all P>0.05). V̇O2 was significantly reduced immediately after UVA10 (P=0.03) despite no change in plasma [NO2-] (P>0.05). There were no differences in [NO2-] or V̇O2 at the 30 min time-point in any condition. UV-A light did not alter plasma [NO3-] at any time point (all P>0.05). 
Conclusions: This study demonstrates that a UV-A dose of 20 J•cm2 is necessary to increase plasma [NO2-] although a smaller dose is capable of reducing V̇O2 at rest. Exposure to UV-A did not significantly reduce BP in this cohort of healthy adults. These data suggest that exposure to sunlight has a meaningful acute impact on metabolic function.
Original languageEnglish
Pages (from-to)1043-1052
JournalEuropean Journal of Applied Physiology
Volume118
Issue number5
Early online date7 Mar 2018
DOIs
Publication statusE-pub ahead of print - 7 Mar 2018

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