Antioxidants and aging: NMR-based evidence of improved skeletal muscle perfusion and energetics
ABSTRACT We sought to examine the potential role of oxidative stress on skeletal muscle function with advancing age. Nuclear magnetic resonance (NMR) was employed to simultaneously assess muscle perfusion (arterial spin labeling) and energetics ((31)P NMR spectroscopy) in the lower leg of young (26 + or - 5 yr, n = 6) and older (70 + or - 5 yr, n = 6) healthy volunteers following the consumption of either placebo (PL) or an oral antioxidant (AO) cocktail (vitamins C and E and alpha-lipoic acid), previously documented to decrease plasma free radical concentration. NMR measurements were made during and after 5 min of moderate intensity (approximately 5 W) plantar flexion exercise. AO administration significantly improved end-exercise perfusion (AO, 50 + or - 5, and PL, 43 + or - 4 ml x 100 g(-1) x min(-1)) and postexercise perfusion area under the curve (AO, 1,286 + or - 236, and PL, 866 + or - 144 ml/100 g) in older subjects, whereas AO administration did not alter hemodynamics in the young group. Concomitantly, muscle oxidative capacity (time constant of phosphocreatine recovery, tau) was improved following AO in the older (AO, 43 + or - 1, and PL, 51 + or - 7 s) but not the young (AO, 54 + or - 5, and PL, 48 + or - 7 s) group. These findings support the concept that oxidative stress may be partially responsible for the age-related decline in skeletal muscle perfusion during physical activity and reveal a muscle metabolic reserve capacity in the elderly that is accessible under conditions of improved perfusion.
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ABSTRACT: Sarcopenia is a geriatric syndrome that is characterized by gradual loss of muscle mass and strength with increasing age. Although the underlying mechanism is still unknown, the contribution of increased oxidative stress in advanced age has been recognized as one of the risk factors of sarcopenia. Thus, eliminating reactive oxygen species (ROS) can be a strategy to combat sarcopenia. In this review, we discuss the potential role of vitamin E in the prevention and treatment of sarcopenia. Vitamin E is a lipid soluble vitamin, with potent antioxidant properties and current evidence suggesting a role in the modulation of signaling pathways. Previous studies have shown its possible beneficial effects on aging and age-related diseases. Although there are evidences suggesting an association between vitamin E and muscle health, they are still inconclusive compared to other more extensively studied chronic diseases such as neurodegenerative diseases and cardiovascular diseases. Therefore, we reviewed the role of vitamin E and its potential protective mechanisms on muscle health based on previous and current in vitro and in vivo studies.07/2014; 2014:16. DOI:10.1155/2014/914853
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ABSTRACT: To determine the effects of age and sex on in vivo mitochondrial function of distinct locomotory muscles, the tibialis anterior (TA) and medial gastrocnemius (MG), of young (Y; 24 ± 3 years) and older (O; 69 ± 4) men (M) and women (W) of similar overall physical activity (PA) was compared. In vivo mitochondrial function was measured using phosphorus magnetic resonance spectroscopy, and PA and physical function were measured in all subjects. Overall PA was similar among the groups, although O (n = 17) had fewer daily minutes of moderate-to-vigorous PA (p = 0.001), and slowed physical function (p < 0.05 for all variables), compared with Y (n = 17). In TA, oxidative capacity (V max; mM s(-1)) was higher in O than Y (p < 0.001; Y = 0.90 ± 0.12; O = 1.12 ± 0.18). There was no effect of age in MG (p = 0.5; Y = 0.91 ± 0.17; O = 0.96 ± 0.24), but women had higher oxidative capacity than men (p = 0.007; M = 0.84 ± 0.18; W = 1.03 ± 0.18). In vivo mitochondrial function was preserved in healthy O men and women, despite lower intensity PA and physical function in this group. The extent to which compensatory changes in gait may be responsible for this preservation warrants further investigation. Furthermore, women had higher oxidative capacity in the MG, but not the TA.Journal of the American Aging Association 10/2014; 36(5):9713. DOI:10.1007/s11357-014-9713-5 · 3.45 Impact Factor
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ABSTRACT: The purpose of this study was to investigate blood flow and its heterogeneity within and among knee muscles of five young (26 ± 6 years) and five old (77 ± 6 years) healthy men with similar physical activity levels when they performed two types of submaximal fatiguing isometric contractions that required either force or position control. Positron emission tomography (PET) and [15O]-H2O were used to determine blood flow two minutes (beginning) and 12 minutes (end) after the start of the tasks. Young and old men had similar maximal forces and endurance times for the fatiguing tasks. Although muscle volumes were lower in the old subjects, total muscle blood flow was similar between the groups (young: 25.8 ± 12.6; old: 25.1 ± 15.4 ml • min-1; age main effect, P = 0.77) since blood flow per unit mass of muscle in the exercising knee extensors was greater for the old men (12.5 ± 6.2 ml • min-1 • 100 g-1) than for the young men (8.6 ± 3.6 ml • min-1 • 100 g-1; age main effect, P = 0.001). Further, blood flow heterogeneity in the exercising knee extensors was significantly lower in the old (56 ± 27 %) compared to the young (67 ± 34 %) men. Taken together, despite smaller skeletal muscles, the intact neural drive to the muscle and the greater, less heterogeneous blood flow per gram of muscle indicates that old fit muscle achieves adequate exercise hyperaemia.The Journal of Physiology 11/2013; 592(2). DOI:10.1113/jphysiol.2013.264614 · 4.54 Impact Factor