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Neurology. 2002 Apr 9;58(7):1088-93.

Resting oxygen consumption and in vivo ADP are increased in myopathy due to complex I deficiency.

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  • 1Department of Pediatric Gastroenterology, University Children's Hospital, Utrecht, The Netherlands.



Patients with isolated complex I deficiency (CID) in skeletal muscle mitochondria often present with exercise intolerance as their major clinical symptom.


To study the in vivo bioenergetics in patients with complex I deficiency in skeletal muscle mitochondria.


In vivo bioenergetics were studied in three of these patients by measuring oxygen uptake at rest and during maximal exercise, together with forearm ADP concentrations ([ADP]) at rest. Whole-body oxygen consumption at rest (VO(2)) was measured with respiratory calorimetry. Maximal oxygen uptake (VO(2)max) was measured during maximal exercise on a cycle ergometer. Resting [ADP] was estimated from in vivo (31)P MRS measurements of inorganic phosphate, phosphocreatine, and ATP content of forearm muscle.


Resting VO(2) was significantly increased in all three patients: 128 +/- 14% (SD) of values in healthy control subjects. VO(2)max in patients was on average 2.8 times their VO(2) at rest and was only 28% of VO(2)max in control subjects. Resting [ADP] in forearm muscle was significantly increased compared with healthy control subjects (patients 26 +/- 2 microM, healthy controls 9 +/- 2 microM).


In patients with CID, the increased whole-body oxygen consumption rate at rest reflects increased electron transport through the respiratory chain, driven by a decreased phosphorylation potential. The increased electron transport rate may compensate for the decreased efficiency of oxidative phosphorylation (phosphorylation potential).

[PubMed - indexed for MEDLINE]
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