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Call Me Radical: Going Anti-Antioxidants ?

Call Me Radical: Going Anti-Antioxidants ?. Kevin L. Shimkus Texas A&M University. Objectives . Identify Reactive Oxygen Species (ROS) and their sources in skeletal muscle Define antioxidants, their interaction with ROS, and identify foods high in antioxidants

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Call Me Radical: Going Anti-Antioxidants ?

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  1. Call Me Radical: Going Anti-Antioxidants? Kevin L. Shimkus Texas A&M University

  2. Objectives • Identify Reactive Oxygen Species (ROS) and their sources in skeletal muscle • Define antioxidants, their interaction with ROS, and identify foods high in antioxidants • Describe potential scenarios regarding ROS + antioxidant supplementation • Inactive/injured individual • Aerobic athlete • Anaerobic athlete

  3. Reactive Oxygen Species (ROS) • Chemical particles with an odd number of electrons • Superoxide (O2•-), Hydroxyl radical (•OH), and Nitric Oxide (NO•) • Produced by normal metabolic reactions in the muscle cell • Mitochondria, SR, t-tubules, sarcolemma, cytosol • Short-lived and quickly combine with molecules such as fats, proteins, and DNA, converting them into free radicals that continue reacting

  4. ROS-induced signaling pathways • ERK 1/2 – MPS • p38 MAPK – apoptosis • NF-κB – nuclear transcription • Activates and deactivates

  5. Antioxidants + ROS Interaction • Antioxidants are molecules that neutralize free radicals • Typically done by converting the free radical to a safer compound • Enzyme superoxide dismutase (SOD) converts superoxide into hydrogen peroxide • Antioxidant deficiencies linked to heart attack, sterility, muscular dystrophy

  6. Dietary Sources • β-Carotene • Yellow, orange, and green leafy vegetables and fruits: carrots, turnips, sweet potatoes, squash, mangoes, papayas, spinach • Vitamin C • Citrus fruits and juices, cabbage, broccoli, cantaloupe, green and red sweet peppers • Vitamin E • Poultry, seafood, vegetable oils, whole-grain breads and fortified cereals, nuts and seeds, eggs

  7. Inactive/Injured Individual • Vitamin E – S. Servaiset al. (2007) • 60 mg/kg 2x/wk for 5wk, HU Winstar final 14d • Bowman-Birk Inhibitor – M. Reid et al. (2007) • Soy protein, 1% concentrate • Mouse model 12d HU

  8. Aerobic Athlete • Male Human: 65%-80% VO2max cycle test (3x/wk for 8wks, unsuppvs 1g/d supp) • Male Winstar: Treadmill tested 5d/wk for 3wks, 6wks, unsuppvs 500mg/kg/d supp • VO2max increased 22% in unsupp group, 10.8% in supplemented group (Human,NS)

  9. Anaerobic Athlete • Type II fiber mitochondria promote higher levels of ROS production (D. Neuferet al. 2006) • Antioxidants blunt post-exercise insulin sensitivity (Ristowet al. 2009) • Ischemia/Reperfusion findings (various authors)

  10. Knowledge Gaps & Complications • Just how much oxidative damage is too much or not enough? • Chronic intense training • Training combined with other environmental stressors • Would ROS production conducive to muscle benefits be debilitating to other tissues? • Blood vessels, heart • Quantifying the levels of different ROS in live cells

  11. Closing Thought

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