title: Ubiquinol: a potential biomarker for tissue energy requirements and oxidative stress.
abstract: BACKGROUND
  Coenzyme Q (CoQ) has been suggested as a biomarker for tissue redox status. The aims are (1) to compare ubiquinol-9, ubiquinol-10, ubiquinone-9, ubiquinone-10, total CoQ content and CoQ redox ratio in quadriceps muscle, heart, brain and liver tissues of mdx mice with wild-type controls; and (2) to determine if ubiquinol content and CoQ redox ratio changes are associated with pathological findings in mdx mouse.
  
  
  METHODS
  CoQ contents were determined in homogenized quadriceps muscle, heart, liver and brain of age-matched mdx and wild-type control mice by HPLC-EC. Light and electron microscopy studies were conducted using standard pathology methods.
  
  
  RESULTS
  Ubiquinol-9 and ubiquinol-10 concentrations are significantly increased in quadriceps and heart muscle of mdx mouse. Increased redox ratios of coenzyme Q(9) and coenzyme Q(10) are also evident in quadriceps, heart and liver tissues in mdx mouse, but not brain. Pathological examination shows marked myofiber regeneration and evidence of mitochondrial proliferation for mdx muscle.
  
  
  CONCLUSIONS
  Evidence that changes in ubiquinol content and CoQ redox ratio are related to pathological features in mdx skeletal and heart myofibers suggests that tissue ubiquinol content and CoQ redox ratio may be useful biomarkers for evaluating muscle disorders associated with mitochondrial proliferation and defects in oxidative phosphorylation.
authors.affiliation: Division of Pathology and Laboratory Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center and University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States.
authors.forename: Lili
authors.initials: L
authors.lastname: Miles
authors.forename: Michael V
authors.initials: MV
authors.lastname: Miles
authors.forename: Peter H
authors.initials: PH
authors.lastname: Tang
authors.forename: Paul S
authors.initials: PS
authors.lastname: Horn
authors.forename: John G
authors.initials: JG
authors.lastname: Quinlan
authors.forename: Brenda
authors.initials: B
authors.lastname: Wong
authors.forename: Alexandra
authors.initials: A
authors.lastname: Wenisch
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Bove
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004734:Energy Metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008854:Microscopy, Electron; D028361:Mitochondrial Diseases; D020388:Muscular Dystrophy, Duchenne / Q000473:pathology*; D009210:Myofibrils / Q000473:pathology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D014018:Tissue Distribution; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000032:analysis
chemical_list: D015415:Biomarkers; D014451:Ubiquinone; C003741:ubiquinol