UVA light, Nitrate and Exercise
Research type
Research Study
Full title
UVA light and NO: An investigation into the effects on oxygen cost of exercise (UVANOX)
IRAS ID
156307
Contact name
Martin Feelisch
Contact email
Sponsor organisation
Research Governance Office
Duration of Study in the UK
0 years, 9 months, 12 days
Research summary
Nitric oxide (NO) is integral to the human physiological response to hypoxia (lack of oxygen). Levett D et al (2011). In a critical care setting, hypoxia may arise as a result of multiple organ malfunctions and ultimately contributes to patient mortality (death), so any measures that can be taken to decrease a patient’s need for oxygen to fulfil normal bodily functions will have an impact on survival.
In healthy individuals, nitrate (the major end product of NO breakdown and also a ubiquitous constituent of our diet) has been shown to reduce the oxygen cost of exercise. Larsen F et al (2010). Thus, nitrate administration may also lower the need for oxygen in critically ill patients.
UVA light has been shown to increase concentrations of NO independently of NO synthase activity. It has been investigated in relation to blood pressure and blood flow regulation, but the mechanisms underpinning this are unknown. Liu D et al (2014). Literature suggests that effects of UVA light are mainly derived from vitamin D. Research showed improved exercise performance when exposed to UVA light during the summer months. Cannell JJ. Et al (2009). The mechanism related to increased performance was ascribed to vitamin D, however, its effects are rather slow (within 24 h) and cannot account for many of immediate effects of UVA light. With vitamin D an unlikely candidate for short or transient changes, the role of NO will be investigated.
It has been hypothesised that the release of NO is via preformed stores in the skin as a result of UVA irradiation. This release was shown to have a measureable reduction on blood pressure demonstrating a systemic effect of the NO on the cardiovascular system. Liu D et al (2014).
Dietary nitrate has been demonstrated to lower upon blood pressure and have a favourable effect on other cardiometabolic risk factors. Kapil V et al. (2010). The hypothesis that NO stored in and released from skin exists in large enough quantities to exert a measureable effect is based upon the observations made by Liu et al (2014) who identified a measureable reduction in blood pressure as a result of NO released from skin.
This research project will attempt to combine two currently disparate concepts: investigate the role of UVA light in releasing NO from storage forms in the skin to see whether this also has an effect on oxygen cost of exercise in healthy individuals (via CPET testing), and whether this effect can be potentiated by combination with supplemental nitrate in the form of natural, commercially available beetroot juice. The project will attempt to see if 1) there is a reduced oxygen cost with UVA and beetroot and 2) mechanisms involved in the process by measuring NO in exhaled breath and by obtaining samples (blood, urine, exhaled NO, saliva) at various time points for NO metabolite analyses and general metabolic screening.
The potential impact of this project for the critically ill patient is substantial. Even a small reduction in a healthy individual’s oxygen cost of exercise could translate into a large survival increase in the critically ill where a small percentage of improvement in cardiovascular function and oxygen delivery could make large improvements in the chances of patient survival.References:
Cannell JJ. Et al. Med Sci Sports Exerc. 2009 May;41(5):1102-10. doi: 10.1249/MSS.0b013e3181930c2b
Kapil V et al. Inorganic nitrate supplementation lowers blood pressure in humans: role for nitrite-derived NO. Hypertension. 2010 Aug;56(2):274-81. doi: 10.1161/HYPERTENSIONAHA.110.153536.
Larsen F et al. Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise. Free Radical Biology & Medicine 48 (2010) 342–347
Levett D et al. The role of nitrogen oxides in human adaption to hypoxia. Scientific reports. 2011. Sci Rep. 2011;1:109. doi: 10.1038/srep00109
Liu D et al. UVA Irradiation of Human Skin Vasodilates Arterial Vasculature and Lowers Blood Pressure Independently of Nitric Oxide Synthase, Journal of Investigative Dermatology. 2014; doi: 10.1038/jid.2014.27.REC name
East Midlands - Nottingham 2 Research Ethics Committee
REC reference
14/EM/1168
Date of REC Opinion
23 Sep 2014
REC opinion
Favourable Opinion