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Skeletal muscle oxidative capacity, fiber type, and metabolites after lung transplantation

journal contribution
posted on 01.07.1999, 00:00 authored by X N Wang, T J Williams, M J McKenna, J L Li, Steve FraserSteve Fraser, E A Side, G I Snell, E H Walters, M F Carey
Lung transplant (LTx) recipients have a low peak work rate, peak oxygen consumption (V O2peak), and early lactate threshold on incremental exercise. We hypothesized that LTx recipients have reduced oxidative function and altered fiber type proportion in peripheral skeletal muscle. Seven stable LTx recipients and seven age- and sex-matched control subjects were studied. Incremental exercise testing with arterialized venous sampling and a resting quadriceps femoris punch muscle biopsy were performed. Muscle specimens were analyzed for fiber type proportion, metabolites, oxidative and glycolytic enzyme activities, and mitochondrial ATP production rate (MAPR) using standard techniques. The results showed that mean V O2peak in LTx recipients was 52% of control subjects. Compared with the control subjects, LTx skeletal muscle exhibited: (1) a lower MAPR; (2) lower activity of the mitochondrial enzymes glutamate dehydrogenase (GDH), citrate synthase (CS), 2-oxogluterate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA-dehydrogenase (HAD). There was no difference in the activities of anaerobic enzymes, except for higher phosphofructokinase activity; (3) a lower proportion of type I fibers; (4) a higher lactate and inosine monophosphate (IMP) content and a lower ATP content at rest indicating a high reliance on anaerobic metabolism. The reduced type I fiber proportion and severely reduced mitochondrial oxidative capacity may play an important role in exercise limitation after LTx.

History

Journal

American journal of respiratory and critical care medicine

Volume

160

Issue

1

Pagination

57 - 63

Publisher

American Lung Association

Location

New York, N.Y.

ISSN

1073-449X

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1999, American Lung Association