Difference between revisions of "Vielhaber 2000 Biochem Soc Trans"
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|year=2000 | |year=2000 | ||
|journal=Biochem Soc Trans | |journal=Biochem Soc Trans | ||
|abstract=Mitochondrial function in saponin-permeabilized | |abstract=Mitochondrial function in saponin-permeabilized muscle fibres can be studied by high-Resolution respirometry, laser-excited fluorescence spectroscopy and fluorescence microscopy. We applied these techniques to study metabolic effects of changes in the pattern of mitochondrial enzymes in skeletal muscle of patients with chronic progressive external ophthalmoplegia or KearnsΒ± | ||
muscle fibres can be studied by high- | Sayre syndrome harbouring large-scale deletions of mitchondrial DNA (mtDNA). In all patients combined deficiencies of respiratory chain enzymes containing mitochondrially encoded subunits were observed. The citrate synthase-normalized | ||
respirometry, laser-excited fluorescence spectroscopy | activity ratios of these enzymes decreased linearly with increasing mtDNA heteroplasmy. This indicates the absence of any well-defined mutation thresholds for mitochondrial enzyme activities in the entire skeletal muscle. We applied metabolic control analysis to perform a quantitative estimation of the metabolic influence of the observed enzyme deficiencies. For patients with | ||
and fluorescence microscopy. We applied | degrees of mtDNA heteroplasmy below about 60% we observed at almost normal maximal rates of respiration an increase in flux control coeficients of Complexes I and CIV. Permeabilized skeletal-muscle fibres of patients with higher degrees of mtDNA heteroplasmy and severe enzyme deficiencies exhibited additionally decreased maximal rates of respiration. This finding indicates the presence of a `metabolic threshold' which can be assessed by functional studies of muscle fibres providing the link to the phenotypic expression of the mtDNA mutation in skeletal muscle. | ||
these techniques to study metabolic effects of | |||
changes in the pattern of mitochondrial enzymes | |||
in skeletal muscle of patients with chronic | |||
progressive external ophthalmoplegia or KearnsΒ± | |||
Sayre syndrome harbouring large-scale deletions | |||
of mitchondrial DNA (mtDNA). In all patients | |||
combined deficiencies of respiratory chain enzymes | |||
containing mitochondrially encoded subunits | |||
were observed. The citrate synthase-normalized | |||
activity ratios of these enzymes decreased | |||
linearly with increasing mtDNA heteroplasmy. | |||
This indicates the absence of any well-defined | |||
mutation thresholds for mitochondrial enzyme | |||
activities in the entire skeletal muscle. We applied | |||
metabolic control analysis to perform a quantitative | |||
estimation of the metabolic influence of the | |||
observed enzyme deficiencies. For patients with | |||
degrees of mtDNA heteroplasmy below about | |||
60%we observed at almost normal maximal rates | |||
of respiration an increase in flux control coeficients of | |||
maximal rates of respiration. This finding indicates the presence of a `metabolic threshold' which can be assessed by functional studies of muscle | |||
fibres providing the link to the phenotypic | |||
|keywords=Genotype, Phenotype relations, Mitochondrial (mt) myopathy, mtDNA deletion | |keywords=Genotype, Phenotype relations, Mitochondrial (mt) myopathy, mtDNA deletion | ||
}} | }} | ||
{{Labeling | {{Labeling | ||
| | |area=Respiration, mtDNA;mt-genetics, mt-Medicine, Patients | ||
|organism=Human | |organism=Human | ||
|tissues=Skeletal muscle | |tissues=Skeletal muscle | ||
|preparations=Permeabilized tissue | |preparations=Permeabilized tissue | ||
|enzymes=Complex I, Complex IV; Cytochrome c Oxidase | |enzymes=Complex I, Complex IV; Cytochrome c Oxidase, Marker Enzyme | ||
|diseases=Inherited | |||
|topics=Flux control, Threshold;excess capacity | |||
|instruments=Oxygraph-2k | |||
|additional=Spectrophotometry; Spectrofluorimetry | |additional=Spectrophotometry; Spectrofluorimetry | ||
}} | }} |
Revision as of 15:12, 12 August 2013
Vielhaber S, Kudin A, Schroder R, Elger CE, Kunz WS (2000) Muscle fibres: applications for the study of the metabolic consequences of enzyme deficiencies in skeletal muscle. Biochem Soc Trans 28: 159-164. |
Vielhaber S, Kudin A, Schroder R, Elger CE, Kunz WS (2000) Biochem Soc Trans
Abstract: Mitochondrial function in saponin-permeabilized muscle fibres can be studied by high-Resolution respirometry, laser-excited fluorescence spectroscopy and fluorescence microscopy. We applied these techniques to study metabolic effects of changes in the pattern of mitochondrial enzymes in skeletal muscle of patients with chronic progressive external ophthalmoplegia or KearnsΒ± Sayre syndrome harbouring large-scale deletions of mitchondrial DNA (mtDNA). In all patients combined deficiencies of respiratory chain enzymes containing mitochondrially encoded subunits were observed. The citrate synthase-normalized activity ratios of these enzymes decreased linearly with increasing mtDNA heteroplasmy. This indicates the absence of any well-defined mutation thresholds for mitochondrial enzyme activities in the entire skeletal muscle. We applied metabolic control analysis to perform a quantitative estimation of the metabolic influence of the observed enzyme deficiencies. For patients with degrees of mtDNA heteroplasmy below about 60% we observed at almost normal maximal rates of respiration an increase in flux control coeficients of Complexes I and CIV. Permeabilized skeletal-muscle fibres of patients with higher degrees of mtDNA heteroplasmy and severe enzyme deficiencies exhibited additionally decreased maximal rates of respiration. This finding indicates the presence of a `metabolic threshold' which can be assessed by functional studies of muscle fibres providing the link to the phenotypic expression of the mtDNA mutation in skeletal muscle. β’ Keywords: Genotype, Phenotype relations, Mitochondrial (mt) myopathy, mtDNA deletion
Labels: MiParea: Respiration, mtDNA;mt-genetics, mt-Medicine, Patients
Pathology: Inherited
Organism: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue Enzyme: Complex I, Complex IV; Cytochrome c Oxidase"Complex IV; Cytochrome c Oxidase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property., Marker Enzyme"Marker Enzyme" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property. Regulation: Flux control, Threshold;excess capacity
HRR: Oxygraph-2k
Spectrophotometry; Spectrofluorimetry