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Exercise‐induced PCr recovery kinetics and tissue oxygenation: The role of free radicals and aging
Author(s) -
Hart Corey R.,
Layec Gwenael,
Trinity Joel D.,
Liu Xin,
Kim SeongEun,
Groot H. Jon,
Jeong EunKee,
Richardson Russell S.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1202.17
Subject(s) - radical , oxygenation , kinetics , microcirculation , chemistry , oxidative phosphorylation , blood flow , oxidative stress , medicine , endocrinology , biochemistry , physics , quantum mechanics
We investigated the role of free radicals on muscle oxidative capacity and O 2 availability in activity matched young (Y) and old (O) people following exercise. 39 subjects (19 Y and 20 O) performed sub‐maximal plantar flexion exercise following the consumption of either a placebo (PL) or an antioxidant (AO) cocktail. PCr resynthesis was assessed by 31 P‐MRS (magnetic resonance spectroscopy), while muscle re‐oxygenation and limb blood flow were evaluated by near‐infrared spectroscopy and ultrasound Doppler, respectively. The PCr recovery time constant in O (PL: 37 ± 6; AO: 38 ± 6 s) and Y (PL: 38 ± 6; AO: 36 ± 4 s) as well as the maximal rate of oxidative ATP synthesis in O (PL: 15 ± 2; AO: 14 ± 2 mM.min −1 ) and Y (PL: 13 ± 2; AO: 15 ± 3 mM.min −1 ) were not altered by age or AO. In contrast, muscle reoxygenation rate, although not affected by age, was slower in the Y following AO, as evidenced by the time constant ( P < 0.05) and mean response time (PL: 49 ± 6; AO: 70 ± 10 s) of deoxy‐Hb recovery, while no difference was observed in the old. These data reveal that, when subjects are activity matched, muscle oxidative capacity is preserved with age. In addition, unlike the O, the compromising effect of the AO on O 2 availability in the microcirculation of the Y, without affecting PCr recovery kinetics, implies that free radicals play a role in blood flow regulation and that O 2 availability exceeds mitochondrial capacity in this population.