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

Chris 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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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 ([Formula: see text]), resting metabolic rate (RMR) and skin temperature were recorded continuously.

RESULTS: None of the measured parameters changed significantly during CON (all P > 0.05). [Formula: see text] and RMR were significantly reduced immediately after UVA10 (P < 0.05) despite no change in plasma [NO2-] (P > 0.05). Immediately after exposure to UVA20, plasma [NO2-] was higher (P = 0.014) and [Formula: see text] and RMR tended to be lower compared to baseline (P = 0.06). There were no differences in [NO2-] or [Formula: see text] at the 30 min time point in any condition. UV-A exposure did not alter systolic BP, diastolic BP or MAP (all P > 0.05). 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 [Formula: see text] and RMR 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
Number of pages10
JournalEuropean Journal of Applied Physiology
Volume118
Issue number5
DOIs
Publication statusPublished - May 2018

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Monaghan, C., McIlvenna, L. C., Liddle, L., Burleigh, M., Weller, R. B., Fernandez, B. O., ... Easton, C. (2018). The effects of two different doses of ultraviolet-A light exposure on nitric oxide metabolites and cardiorespiratory outcomes. European Journal of Applied Physiology, 118(5), 1043-1052. https://doi.org/10.1007/s00421-018-3835-x