title: Evaluation of methods for the determination of mitochondrial respiratory chain enzyme activities in human skeletal muscle samples.
abstract: The quantification of mitochondrial enzyme activities in skeletal muscle samples of patients suspected of having mitochondrial myopathies is problematic. Therefore, we have evaluated different methods for the determination of activities cytochrome c oxidase and NADH:CoQ oxidoreductase in human skeletal muscle samples. The measurement of cytochrome c oxidase activity in the presence of 200 microM ferrocytochrome c and the detection of NADH:CoQ oxidoreductase as rotenone-sensitive NADH:CoQ(1) reductase resulted in comparable citrate synthase-normalized respiratory chain enzyme activities of both isolated mitochondria and homogenates from control human skeletal muscle samples. These methods allowed the precise detection of deficiencies of respiratory chain enzymes in skeletal muscle of two patients harboring only 20 and 27% of deleted mitochondrial DNA, respectively. Therefore, citrate synthase-normalized respiratory chain activities can serve as stable reference values for the determination of a putative mitochondrial defect in human skeletal muscle.
authors.affiliation: Department of Epileptology, Department of Neurology, University Bonn Medical Center, Sigmund-Freud-Strasse 25, Bonn, D-53105, Germany.
authors.forename: F R
authors.initials: FR
authors.lastname: Wiedemann
authors.forename: S
authors.initials: S
authors.lastname: Vielhaber
authors.forename: R
authors.initials: R
authors.lastname: Schröder
authors.forename: C E
authors.initials: CE
authors.lastname: Elger
authors.forename: W S
authors.initials: WS
authors.lastname: Kunz
mesh_terms: D000328:Adult; D000818:Animals; D002417:Cattle; D004579:Electron Transport; D042967:Electron Transport Complex I; D003576:Electron Transport Complex IV / Q000032:analysis* / Q000378:metabolism; D005069:Evaluation Studies as Topic; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008931:Mitochondria, Muscle / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000032:analysis* / Q000378:metabolism; D011048:Polarography; D015203:Reproducibility of Results; D013053:Spectrophotometry
chemical_list: D009247:NADH, NADPH Oxidoreductases; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I