title: Free radicals generated by contracting muscle: by-products of metabolism or key regulators of muscle function?
abstract: Skeletal muscle fibers generate reactive oxygen species (ROS) at a number of subcellular sites and this generation is increased by contractile activity. Early studies suggested that generation of superoxide as a by-product of mitochondrial oxygen consumption was the major source of muscle ROS generation and that the species produced were inevitably damaging to muscle, but recent data argue against both of these possibilities. Developments in analytical approaches have shown that specific ROS are generated in a controlled manner by skeletal muscle fibers in response to physiological stimuli and play important roles in the physiological adaptations of muscle to contractions. These include optimization of contractile performance and initiation of key adaptive changes in gene expression to the stresses of contractions. These positive benefits of the ROS that are induced by contractile activity contrast starkly with the increasing evidence that ROS-induced degenerative pathways are fundamental to aging processes in skeletal muscle. A fuller understanding of these contrasting roles is recognized to be important in the design of strategies to maintain and optimize skeletal muscle function during exercise and to help prevent the devastating effects of sarcopenia and other muscle-wasting conditions.
authors.affiliation: Division of Metabolic and Cellular Medicine, School of Clinical Sciences, University of Liverpool, Liverpool L69 3GA, UK. m.j.jackson@liverpool.ac.uk
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Jackson
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D019610:Cytoprotection / Q000187:drug effects; D005609:Free Radicals / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000494:pharmacology; D017695:Soft Tissue Injuries / Q000209:etiology; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D017382:Reactive Oxygen Species; D014810:Vitamin E