Respiratory chain enzyme defects in patients with idiopathic inflammatory myopathy.
OBJECTIVE
To analyse muscle respiratory chain enzymes in idiopathic inflammatory myopathy.


METHODS
Four consecutive female patients seen at our hospital with idiopathic inflammatory myopathy were studied. Muscle histochemical staining included NADH tetrazolium reductase and succinate dehydrogenase tests. Activity of rotenone sensitive NADH cytochrome c reductase (complex I and III) succinate dehydrogenase (complex II), succinate cytochrome c reductase (complex II and III), cytochrome c oxidase (complex IV), and citrate synthase (a mitochondrial matrix enzyme), was measured spectrophotometrically in muscle homogenates. Free carnitine, and short and long chain acylcarnitine esters were determined in muscle homogenates by a radiochemical procedure.


RESULTS
Three patients had mitochondrial proliferation in nonregenerating muscle fibres; these patients had defects of respiratory chain enzyme complexes. Carnitine concentrations, measured in two of the four patients, revealed carnitine deficiency in one.


CONCLUSIONS
Our results suggest that mitochondrial dysfunction may be present in patients with inflammatory myositis.
Campos
Y
Y
Research Unit, Hospital Doce de Octubre, Madrid, Spain.
Arenas
J
J
Cabello
A
A
Gomez-Reino
J J
JJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D002331:Carnitine / Q000032:analysis; D002950:Citrate (si)-Synthase / Q000032:analysis; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000032:analysis; D005260:Female; D006801:Humans; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000473:pathology; D018482:Muscle, Skeletal / Q000201:enzymology*; D009220:Myositis / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D009245:NADH Dehydrogenase / Q000032:analysis; D009246:NADH Tetrazolium Reductase / Q000032:analysis*; D013384:Succinate Cytochrome c Oxidoreductase / Q000032:analysis; D013385:Succinate Dehydrogenase / Q000032:analysis*
D013384:Succinate Cytochrome c Oxidoreductase; D013385:Succinate Dehydrogenase; D009246:NADH Tetrazolium Reductase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D002331:Carnitine