title: Eliminating Nox2 reactive oxygen species production protects dystrophic skeletal muscle from pathological calcium influx assessed in vivo by manganese-enhanced magnetic resonance imaging.
abstract: Inhibiting Nox2 reactive oxygen species (ROS) production reduced in vivo calcium influx in dystrophic muscle. The lack of Nox2 ROS production protected against decreased in vivo muscle function in dystrophic mice. Manganese-enhanced magnetic resonance imaging (MEMRI) was able to detect alterations in basal calcium levels in skeletal muscle and differentiate disease status. Administration of Mn2+did not affect muscle function or the health of the animal, and Mn2+was cleared from skeletal muscle rapidly. We conclude that MEMRI may be a viable, non-invasive technique to monitor molecular alterations in disease progression and evaluate the effectiveness of potential therapies for Duchenne muscular dystrophy.
  
  
  
  Duchenne muscular dystrophy (DMD) is an X-linked progressive degenerative disease resulting from a mutation in the gene that encodes dystrophin, leading to decreased muscle mechanical stability and force production. Increased Nox2 reactive oxygen species (ROS) production and sarcolemmal Ca2+influx are early indicators of disease pathology, and eliminating Nox2 ROS production reduces aberrant Ca2+influx in young mdx mice, a model of DMD. Various imaging modalities have been used to study dystrophic muscle in vivo; however, they are based upon alterations in muscle morphology or inflammation. Manganese has been used for indirect monitoring of calcium influx across the sarcolemma and may allow detection of molecular alterations in disease progression in vivo using manganese-enhanced magnetic resonance imaging (MEMRI). Therefore, we hypothesized that eliminating Nox2 ROS production would decrease calcium influx in adult mdx mice and that MEMRI would be able to monitor and differentiate disease status in dystrophic muscle. Both in vitro and in vivo data demonstrate that eliminating Nox2 ROS protected against aberrant Ca2+influx and improved muscle function in dystrophic muscle. MEMRI was able to differentiate between different pathological states in vivo, with no long-term effects on animal health or muscle function. We conclude that MEMRI is a viable, non-invasive technique to differentiate disease status and might provide a means to monitor and evaluate the effectiveness of potential therapies in dystrophic muscle.
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Loehr
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Stinnett
authors.affiliation: Department of Chemistry, Rice University, Houston, TX, USA.
authors.forename: Mayra
authors.initials: M
authors.lastname: Hernández-Rivera
authors.affiliation: SMART Program, Baylor College of Medicine, Houston, TX, USA.|Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Wesley T
authors.initials: WT
authors.lastname: Roten
authors.affiliation: Department of Chemistry, Rice University, Houston, TX, USA.
authors.forename: Lon J
authors.initials: LJ
authors.lastname: Wilson
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Robia G
authors.initials: RG
authors.lastname: Pautler
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA. rodney@bcm.edu.
authors.forename: George G
authors.initials: GG
authors.lastname: Rodney
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008345:Manganese / Q000493:pharmacokinetics; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000378:metabolism*; D020388:Muscular Dystrophy, Duchenne / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D008345:Manganese; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D002118:Calcium
keywords: Duchenne muscular dystrophy; MEMRI; sarcolemmal calcium influx