Sedentary aging increases resting and exercise-induced intramuscular free radical formation.
Mitochondrial free radical formation has been implicated as a potential mechanism underlying degenerative senescence, although human data are lacking. Therefore, the present study was designed to examine if resting and exercise-induced intramuscular free radical-mediated lipid peroxidation is indeed increased across the spectrum of sedentary aging. Biopsies were obtained from the vastus lateralis in six young (26 + or - 6 yr) and six aged (71 + or - 6 yr) sedentary males at rest and after maximal knee extensor exercise. Aged tissue exhibited greater (P < 0.05 vs. the young group) electron paramagnetic resonance signal intensity of the mitochondrial ubisemiquinone radical both at rest (+138 + or - 62%) and during exercise (+143 + or - 40%), and this was further complemented by a greater increase in alpha-phenyl-tert-butylnitrone adducts identified as a combination of lipid-derived alkoxyl-alkyl radicals (+295 + or - 96% and +298 + or - 120%). Lipid hydroperoxides were also elevated at rest (0.190 + or - 0.169 vs. 0.148 + or - 0.071 nmol/mg total protein) and during exercise (0.567 + or - 0.259 vs. 0.320 + or - 0.263 nmol/mg total protein) despite a more marked depletion of ascorbate and uptake of alpha/beta-carotene, retinol, and lycopene (P < 0.05 vs. the young group). The impact of senescence was especially apparent when oxidative stress biomarkers were expressed relative to the age-related decline in mitochondrial volume density and absolute power output at maximal exercise. In conclusion, these findings confirm that intramuscular free radical-mediated lipid peroxidation is elevated at rest and during acute exercise in aged humans.
Neurovascular Research Laboratory, Faculty of Health, Science and Sport, Univ. of Glamorgan, Mid-Glamorgan, South Wales UK CF37 1DL. dbailey1@glam.ac.uk
Damian M
DM
Bailey
Jane
J
McEneny
Odile
O
Mathieu-Costello
Robert R
RR
Henry
Philip E
PE
James
Joe M
JM
McCord
Sylvia
S
Pietri
Ian S
IS
Young
Russell S
RS
Richardson
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D002338:Carotenoids / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D015444:Exercise; D005609:Free Radicals / Q000378:metabolism*; D006801:Humans; D015227:Lipid Peroxidation; D000077276:Lycopene; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism; D009119:Muscle Contraction; D018384:Oxidative Stress; D052097:Quadriceps Muscle / Q000378:metabolism*; D012146:Rest; D057185:Sedentary Behavior; D013997:Time Factors; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism; D014801:Vitamin A / Q000378:metabolism; D055815:Young Adult; D019207:beta Carotene / Q000378:metabolism
D000975:Antioxidants; D015415:Biomarkers; D003497:Cyclic N-Oxides; D005609:Free Radicals; D019207:beta Carotene; D014801:Vitamin A; D014451:Ubiquinone; D002338:Carotenoids; C029217:phenyl-N-tert-butylnitrone; C041635:alpha-carotene; C024989:coenzyme Q10; D001205:Ascorbic Acid; D000077276:Lycopene