Document Detail

An unusual metabolic myopathy: a malate-aspartate shuttle defect.
MedLine Citation:
PMID:  3440868     Owner:  NLM     Status:  MEDLINE    
Studies on a 27-year-old man with a 3-year history of exercise-induced muscle pain, passage of red urine and elevated serum creatine kinase are described. Histological examination of a biopsy from quadriceps revealed non-specific myopathic changes with occasional clusters of subsarcolemmal mitochondria. The phosphorylase stain was normal. Phosphorous nuclear magnetic resonance (NMR) spectroscopy studies of gastrocnemius and flexor digitorum superficialis muscles showed no abnormalities at rest. During aerobic exercise there was an abnormally rapid decrease in phosphocreatine concentration but the pH remained within the normal range. There was a build-up of phosphomonoester (probably glucose 6-phosphate), usually indicative of a block in glycolysis. However, a primary defect in the glycolytic pathway seemed unlikely because muscle acidified normally during ischaemic exercise. Recovery from exercise was unusual in that phosphocreatine resynthesis and inorganic phosphate disappearance followed similar prolonged time courses (in control subjects the rate of inorganic phosphate disappearance was about twice as fast as the rate of phosphocreatine resynthesis). The transport of inorganic phosphate into the mitochondria appeared to be delayed. These slow recovery data suggested that oxidative metabolism was impaired. However, with all substrates tested, isolated muscle mitochondria had rates of oxygen uptake that were similar to control values, thereby ruling out a primary defect in mitochondrial respiration. A system involving several mitochondrial transport systems, the malate-aspartate shuttle, was measured. The activity in the patient's isolated mitochondria was less than 20% of the activity present in samples from control subjects. This patient is the only one so far reported with a defect involving the malate-aspartate shuttle system.
D J Hayes; D J Taylor; P J Bore; D Hilton-Jones; D L Arnold; M V Squier; A E Gent; G K Radda
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the neurological sciences     Volume:  82     ISSN:  0022-510X     ISO Abbreviation:  J. Neurol. Sci.     Publication Date:  1987 Dec 
Date Detail:
Created Date:  1988-04-21     Completed Date:  1988-04-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375403     Medline TA:  J Neurol Sci     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  27-39     Citation Subset:  IM    
Department of Biochemistry, University of Oxford, U.K.
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MeSH Terms
Aspartic Acid / metabolism*
Magnetic Resonance Spectroscopy
Malates / metabolism*
Mitochondria, Muscle / metabolism,  pathology
Muscular Diseases / metabolism*,  pathology
Reg. No./Substance:
0/Malates; 56-84-8/Aspartic Acid

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