title: Acute exercise remodels mitochondrial membrane interactions in mouse skeletal muscle.
abstract: A unique property of mitochondria in mammalian cells is their ability to physically interact and undergo dynamic events of fusion/fission that remodel their morphology and possibly their function. In cultured cells, metabolic perturbations similar to those incurred during exercise influence mitochondrial fusion and fission processes, but it is unknown whether exercise acutely alters mitochondrial morphology and/or membrane interactions in vivo. To study this question, we subjected mice to a 3-h voluntarily exercise intervention following their normal physical activity patterns, and quantified mitochondrial morphology and membrane interactions in the soleus using a quantitative electron microscopy approach. A single exercise bout effectively decreased blood glucose (P < 0.05) and intramyocellular lipid content (P < 0.01), indicating increased muscle metabolic demand. The number of mitochondria spanning Z-lines and proportion of electron-dense contact sites (EDCS) between adjacent mitochondrial membranes were increased immediately after exercise among both subsarcolemmal (+116%, P < 0.05) and intermyofibrillar mitochondria (+191%, P < 0.001), indicating increased physical interactions. Mitochondrial morphology, and abundance of the mitochondrial pro-fusion proteins Mfn2 and OPA1 were unchanged. Collectively, these results support the notion that mitochondrial membrane dynamics are actively remodelled in skeletal muscle, which may be regulated by contractile activity and the metabolic state. Future studies are required to understand the implications of mitochondrial dynamics in skeletal muscle physiology during exercise and inactivity.
authors: Mitochondrial Research Group, Institute for Ageing and Health, University of Newcastle, Newcastle upon Tyne, United Kingdom;
authors: Martin
authors: M
authors: Picard
authors: Benoit J
authors: BJ
authors: Gentil
authors: Meagan J
authors: MJ
authors: McManus
authors: Kathryn
authors: K
authors: White
authors: Kyle
authors: K
authors: St Louis
authors: Sarah E
authors: SE
authors: Gartside
authors: Douglas C
authors: DC
authors: Wallace
authors: Douglass M
authors: DM
authors: Turnbull
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004734:Energy Metabolism; D005260:Female; D020558:GTP Phosphohydrolases / Q000378:metabolism; D050356:Lipid Metabolism; D008561:Membrane Fusion; D051379:Mice; D008810:Mice, Inbred C57BL; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008931:Mitochondria, Muscle / Q000378:metabolism / Q000648:ultrastructure*; D063154:Mitochondrial Dynamics; D051336:Mitochondrial Membranes / Q000378:metabolism / Q000648:ultrastructure*; D053142:Mitochondrial Size; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism / Q000648:ultrastructure*; D010805:Physical Conditioning, Animal; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D020558:GTP Phosphohydrolases; C488751:Mfn2 protein, mouse; C498809:Opa1 protein, mouse
keywords: exercise; fusion; metabolic state; mitochondrial dynamics; skeletal muscle
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