title: Role of superoxide-nitric oxide interactions in the accelerated age-related loss of muscle mass in mice lacking Cu,Zn superoxide dismutase.
abstract: Mice lacking Cu,Zn superoxide dismutase (SOD1) show accelerated, age-related loss of muscle mass. Lack of SOD1 may lead to increased superoxide, reduced nitric oxide (NO), and increased peroxynitrite, each of which could initiate muscle fiber loss. Single muscle fibers from flexor digitorum brevis of wild-type (WT) and Sod1(-/-) mice were loaded with NO-sensitive (4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, DAF-FM) and superoxide-sensitive (dihydroethidium, DHE) probes. Gastrocnemius muscles were analyzed for SOD enzymes, nitric oxide synthases (NOS), and 3-nitrotyrosine (3-NT) content. A lack of SOD1 did not increase superoxide availability at rest because no increase in ethidium or 2-hydroxyethidium (2-HE) formation from DHE was seen in fibers from Sod1(-/-) mice compared with those from WT mice. Fibers from Sod1(-/-) mice had decreased NO availability (decreased DAF-FM fluorescence), increased 3-NT in muscle proteins indicating increased peroxynitrite formation and increased content of peroxiredoxin V (a peroxynitrite reductase), compared with WT mice. Muscle fibers from Sod1(-/-) mice showed substantially reduced generation of superoxide in response to contractions compared with fibers from WT mice. Inhibition of NOS did not affect DHE oxidation in fibers from WT or Sod1(-/-) mice at rest or during contractions, but transgenic mice overexpressing nNOS showed increased DAF-FM fluorescence and reduced DHE oxidation in resting muscle fibers. It is concluded that formation of peroxynitrite in muscle fibers is a major effect of lack of SOD1 in Sod1(-/-) mice and may contribute to fiber loss in this model, and that NO regulates superoxide availability and peroxynitrite formation in muscle.
authors: Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.
authors: Giorgos K
authors: GK
authors: Sakellariou
authors: Deborah
authors: D
authors: Pye
authors: Aphrodite
authors: A
authors: Vasilaki
authors: Lea
authors: L
authors: Zibrik
authors: Jesus
authors: J
authors: Palomero
authors: Tabitha
authors: T
authors: Kabayo
authors: Francis
authors: F
authors: McArdle
authors: Holly
authors: H
authors: Van Remmen
authors: Arlan
authors: A
authors: Richardson
authors: James G
authors: JG
authors: Tidball
authors: Anne
authors: A
authors: McArdle
authors: Malcolm J
authors: MJ
authors: Jackson
mesh_terms: D000375:Aging / Q000378:metabolism / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D024403:Carbonic Anhydrase III / Q000378:metabolism; D004558:Electric Stimulation; D004996:Ethidium / Q000031:analogs & derivatives / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D005453:Fluorescence; D007537:Isometric Contraction; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D013481:Superoxides / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: C506392:2-hydroxyethidium; C503301:4-amino-5-methylamino-2',7'-difluorofluorescein diacetate; D005452:Fluoresceins; D017382:Reactive Oxygen Species; C067883:dihydroethidium; D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D054464:Peroxiredoxins; D019001:Nitric Oxide Synthase; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D024403:Carbonic Anhydrase III; D004996:Ethidium