Hypoxia compounds exercise-induced free radical formation in humans; partitioning contributions from the cerebral and femoral circulation
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Hypoxia compounds exercise-induced free radical formation in humans; partitioning contributions from the cerebral and femoral circulation. / Bailey, Damian M; Rasmussen, Peter; Evans, Kevin A; Bohm, Aske M; Zaar, Morten; Nielsen, Henning B; Brassard, Patrice; Nordsborg, Nikolai Baastrup; Homann, Pernille Halberg; Raven, Peter B; McEneny, Jane; Young, Ian S; McCord, Joe M; Secher, Niels H.
I: Free Radical Biology & Medicine, Bind 124, 2018, s. 104-113.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Hypoxia compounds exercise-induced free radical formation in humans; partitioning contributions from the cerebral and femoral circulation
AU - Bailey, Damian M
AU - Rasmussen, Peter
AU - Evans, Kevin A
AU - Bohm, Aske M
AU - Zaar, Morten
AU - Nielsen, Henning B
AU - Brassard, Patrice
AU - Nordsborg, Nikolai Baastrup
AU - Homann, Pernille Halberg
AU - Raven, Peter B
AU - McEneny, Jane
AU - Young, Ian S
AU - McCord, Joe M
AU - Secher, Niels H.
N1 - CURIS 2018 NEXS 209
PY - 2018
Y1 - 2018
N2 - This study examined to what extent the human cerebral and femoral circulation contribute to free radical formation during basal and exercise-induced responses to hypoxia. Healthy participants (5♂, 5♀) were randomly assigned single-blinded to normoxic (21% O2) and hypoxic (10% O2) trials with measurements taken at rest and 30min after cycling at 70% of maximal power output in hypoxia and equivalent relative and absolute intensities in normoxia. Blood was sampled from the brachial artery (a), internal jugular and femoral veins (v) for non-enzymatic antioxidants (HPLC), ascorbate radical (A•-, electron paramagnetic resonance spectroscopy), lipid hydroperoxides (LOOH) and low density lipoprotein (LDL) oxidation (spectrophotometry). Cerebral and femoral venous blood flow was evaluated by transcranial Doppler ultrasound (CBF) and constant infusion thermodilution (FBF). With 3 participants lost to follow up (final n = 4♂, 3♀), hypoxia increased CBF and FBF (P = 0.041 vs. normoxia) with further elevations in FBF during exercise (P = 0.002 vs. rest). Cerebral and femoral ascorbate and α-tocopherol consumption (v < a) was accompanied by A•-/LOOH formation (v > a) and increased LDL oxidation during hypoxia (P < 0.043 to 0.049 vs. normoxia) implying free radical-mediated lipid peroxidation subsequent to inadequate antioxidant defense. This was pronounced during exercise across the femoral circulation in proportion to the increase in local O2 uptake (r = -0.397 to -0.459, P = 0.037 to 0.045) but unrelated to any reduction in PO2. These findings highlight considerable regional heterogeneity in the oxidative stress response to hypoxia that may be more attributable to local differences in O2 flux than to O2 tension.
AB - This study examined to what extent the human cerebral and femoral circulation contribute to free radical formation during basal and exercise-induced responses to hypoxia. Healthy participants (5♂, 5♀) were randomly assigned single-blinded to normoxic (21% O2) and hypoxic (10% O2) trials with measurements taken at rest and 30min after cycling at 70% of maximal power output in hypoxia and equivalent relative and absolute intensities in normoxia. Blood was sampled from the brachial artery (a), internal jugular and femoral veins (v) for non-enzymatic antioxidants (HPLC), ascorbate radical (A•-, electron paramagnetic resonance spectroscopy), lipid hydroperoxides (LOOH) and low density lipoprotein (LDL) oxidation (spectrophotometry). Cerebral and femoral venous blood flow was evaluated by transcranial Doppler ultrasound (CBF) and constant infusion thermodilution (FBF). With 3 participants lost to follow up (final n = 4♂, 3♀), hypoxia increased CBF and FBF (P = 0.041 vs. normoxia) with further elevations in FBF during exercise (P = 0.002 vs. rest). Cerebral and femoral ascorbate and α-tocopherol consumption (v < a) was accompanied by A•-/LOOH formation (v > a) and increased LDL oxidation during hypoxia (P < 0.043 to 0.049 vs. normoxia) implying free radical-mediated lipid peroxidation subsequent to inadequate antioxidant defense. This was pronounced during exercise across the femoral circulation in proportion to the increase in local O2 uptake (r = -0.397 to -0.459, P = 0.037 to 0.045) but unrelated to any reduction in PO2. These findings highlight considerable regional heterogeneity in the oxidative stress response to hypoxia that may be more attributable to local differences in O2 flux than to O2 tension.
KW - Faculty of Science
KW - Hypoxia
KW - Exercise
KW - Free radicals
KW - Muscle
KW - Brain
U2 - 10.1016/j.freeradbiomed.2018.05.090
DO - 10.1016/j.freeradbiomed.2018.05.090
M3 - Journal article
C2 - 29859345
VL - 124
SP - 104
EP - 113
JO - Free Radical Biology & Medicine
JF - Free Radical Biology & Medicine
SN - 0891-5849
ER -
ID: 197436344