Nyberg, Michael Permin4; Mortensen, Stefan Peter5; Cabo, Helena3; Gomez-Cabrera, Mari-Carmen3; Viña, Jose3; Hellsten, Ylva4
1 Integrated Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, Københavns Universitet2 Section of Surgery and Internal Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet3 Department of Physiology, Faculty of Medicine, University of Valencia, Fundación Investigacion Hospital Clinico Universitario/ INCLIVA, Spain.4 Integrated Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, Københavns Universitet5 Section of Surgery and Internal Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
Reactive oxygen species (ROS) are important signaling molecules with regulatory functions, and in young and adult organisms, the formation of ROS is increased during skeletal muscle contractions. However, ROS can be deleterious to cells when not sufficiently counterbalanced by the antioxidant system. Aging is associated with accumulation of oxidative damage to lipids, DNA and proteins. Given the pro-oxidant effect of skeletal muscle contractions, this effect of age could be a result of excessive ROS formation. We evaluated the effect of acute exercise on changes in blood redox state across the leg of young (23±1 years) and older (66±2 years) sedentary humans by measuring the whole blood concentration of the reduced (GSH) and oxidized (GSSG) form of the antioxidant glutathione. To assess the role of physical activity, lifelong physically active older subjects (62±2 years) were included. Exercise increased the venous concentration of GSSG in an intensity-dependent manner in young sedentary subjects, suggesting an exercise-induced increase in ROS formation. In contrast, venous GSSG levels remained unaltered during exercise in the older sedentary and active groups despite a higher skeletal muscle expression of the superoxide generating enzyme NADPH oxidase. Arterial concentration of GSH and expression of antioxidant enzymes in skeletal muscle of older active subjects was found to be increased. The potential impairment in exercise-induced ROS formation may be an important mechanism underlying skeletal muscle and vascular dysfunction with sedentary aging. Lifelong physical activity up-regulates antioxidant systems which may be one of the mechanisms underlying the lack of exercise-induced increase in GSSG.
Free Radical Biology and Medicine, 2014, Vol 73, p. 166-173