TY - JOUR
T1 - Dose-dependent Effects Of Uv-a Light On Nitric Oxide Bioavailability And Cardiometabolic Function In Humans
AU - Monaghan, Chris
AU - McIlvenna, Luke C.
AU - Cousins Burleigh, Mia
AU - Fernandez, Bernadette O.
AU - Feelisch, Martin
AU - Muggeridge, David
AU - Easton, Chris
PY - 2016/5
Y1 - 2016/5
N2 - Exposing human skin to 20 J·cm2 of
ultraviolet-A (UV-A) light has been shown to release nitric oxide (NO) species
from dermal storage forms and mildly reduce blood pressure (BP). The
dose-response relationship of these effects, however, remains unknown.
PURPOSE: To determine the effects of two different
doses of UV-A light on NO metabolites, mean arterial pressure (MAP) and resting
energy expenditure (REE).
METHODS: Eight healthy males (age: 28 ± 5 yr, body
mass: 81 ± 12 kg) were exposed to three light conditions in a randomised
counter-balanced order. Following at least 30 min of supine rest, participants
were exposed to either (i) no light (CON) (ii) 10 J·cm2 UV-A
light (UVA10), or (iii) 20 J·cm2 UV-A light (UVA20). UVA20 is
comparable to 30 min of sunshine in southern Europe in summer. During the
experiment oxygen consumption (VO2) and REE were monitored
continuously using indirect calorimetry. Regular BP measurements were taken and
samples of venous blood collected before and after light exposure. Plasma
nitrate [NO3-] and nitrite [NO2-]
were later analysed via HPLC (n=7). Statistical differences are reported
together with effect sizes (Cohen’s d) where appropriate.
RESULTS: There were no significant changes in plasma
[NO3-] or [NO2-] between pre- and
post-exposures in all conditions (P>0.05). Plasma [NO2-]
was moderately higher after UVA20 exposure compared to CON (Δ 29%, 178 ± 299
nM, d=0.58, P=0.17) but increased to only a small
extent with UV10 (Δ 9%, 58 ± 220 nM, d=0.26, P=0.51).
There were no differences in MAP between conditions or before and after
exposure (both P>0.50). There was a marked decline in REE
following UVA20 (Δ 7%, 112 ± 143 kcal/day, d=0.78, P<0.01)
and UV10 (Δ 4% 134± 159 kcal/day, d=0.84, P=0.07) while
no significant differences were observed in the CON group (P=1.0). From
pre- to post-light exposure, VO2 declined with UVA20 (Δ 6%, 13
± 19 ml/min, P=0.04), but did not change with UVA10 (P=0.26)
or CON (P=0.44).
CONCLUSION: The present data suggests that a 20 J·cm2 dose
of UV-A light increases [NO2-] and decreases REE and VO2 to
a greater extent than 10 J·cm2. Although speculative, it is probable
that reductions in REE and VO2 were mediated by an increased NO
availability. Neither dose of UV-A light resulted in a detectable change in BP
although a larger sample is required before definitive conclusions can be made.
AB - Exposing human skin to 20 J·cm2 of
ultraviolet-A (UV-A) light has been shown to release nitric oxide (NO) species
from dermal storage forms and mildly reduce blood pressure (BP). The
dose-response relationship of these effects, however, remains unknown.
PURPOSE: To determine the effects of two different
doses of UV-A light on NO metabolites, mean arterial pressure (MAP) and resting
energy expenditure (REE).
METHODS: Eight healthy males (age: 28 ± 5 yr, body
mass: 81 ± 12 kg) were exposed to three light conditions in a randomised
counter-balanced order. Following at least 30 min of supine rest, participants
were exposed to either (i) no light (CON) (ii) 10 J·cm2 UV-A
light (UVA10), or (iii) 20 J·cm2 UV-A light (UVA20). UVA20 is
comparable to 30 min of sunshine in southern Europe in summer. During the
experiment oxygen consumption (VO2) and REE were monitored
continuously using indirect calorimetry. Regular BP measurements were taken and
samples of venous blood collected before and after light exposure. Plasma
nitrate [NO3-] and nitrite [NO2-]
were later analysed via HPLC (n=7). Statistical differences are reported
together with effect sizes (Cohen’s d) where appropriate.
RESULTS: There were no significant changes in plasma
[NO3-] or [NO2-] between pre- and
post-exposures in all conditions (P>0.05). Plasma [NO2-]
was moderately higher after UVA20 exposure compared to CON (Δ 29%, 178 ± 299
nM, d=0.58, P=0.17) but increased to only a small
extent with UV10 (Δ 9%, 58 ± 220 nM, d=0.26, P=0.51).
There were no differences in MAP between conditions or before and after
exposure (both P>0.50). There was a marked decline in REE
following UVA20 (Δ 7%, 112 ± 143 kcal/day, d=0.78, P<0.01)
and UV10 (Δ 4% 134± 159 kcal/day, d=0.84, P=0.07) while
no significant differences were observed in the CON group (P=1.0). From
pre- to post-light exposure, VO2 declined with UVA20 (Δ 6%, 13
± 19 ml/min, P=0.04), but did not change with UVA10 (P=0.26)
or CON (P=0.44).
CONCLUSION: The present data suggests that a 20 J·cm2 dose
of UV-A light increases [NO2-] and decreases REE and VO2 to
a greater extent than 10 J·cm2. Although speculative, it is probable
that reductions in REE and VO2 were mediated by an increased NO
availability. Neither dose of UV-A light resulted in a detectable change in BP
although a larger sample is required before definitive conclusions can be made.
U2 - 10.1249/01.mss.0000486121.41975.74
DO - 10.1249/01.mss.0000486121.41975.74
M3 - Meeting abstract
SN - 0195-9131
VL - 48
SP - 370
JO - Medicine and Science in Sports and Exercise
JF - Medicine and Science in Sports and Exercise
IS - 5S
ER -
