Paradoxical effects of endurance training and chronic hypoxia on myofibrillar ATPase activity

Details

Serval ID
serval:BIB_21666B287341
Type
Article: article from journal or magazin.
Collection
Publications
Title
Paradoxical effects of endurance training and chronic hypoxia on myofibrillar ATPase activity
Journal
American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Author(s)
Roels B., Reggiani C., Reboul C., Lionne C., Iorga B., Obert P., Tanguy S., Gibault A., Jougla A., Travers F., Millet G.P., Candau R.
ISSN
0363-6119
Publication state
Published
Issued date
06/2008
Peer-reviewed
Oui
Volume
294
Number
6
Pages
R1911-1918
Language
english
Notes
Publication types: Journal Article
Abstract
This study aimed to determine the changes in soleus myofibrillar ATPase (m-ATPase) activity and myosin heavy chain (MHC) isoform expression after endurance training and/or chronic hypoxic exposure. Dark Agouti rats were randomly divided into four groups: control, normoxic sedentary (N; n = 14), normoxic endurance trained (NT; n = 14), hypoxic sedentary (H; n = 10), and hypoxic endurance trained (HT; n = 14). Rats lived and trained in normoxia at 760 mmHg (N and NT) or hypobaric hypoxia at 550 mmHg (approximately 2,800 m) (H and HT). m-ATPase activity was measured by rapid flow quench technique; myosin subunits were analyzed with mono- and two-dimensional gel electrophoresis. Endurance training significantly increased m-ATPase (P < 0.01), although an increase in MHC-I content occurred (P < 0.01). In spite of slow-to-fast transitions in MHC isoform distribution in chronic hypoxia (P < 0.05) no increase in m-ATPase was observed. The rate constants of m-ATPase were 0.0350 +/- 0.0023 s(-1) and 0.047 +/- 0.0050 s(-1) for N and NT and 0.033 +/- 0.0021 s(-1) and 0.038 +/- 0.0032 s(-1) for H and HT. Thus, dissociation between variations in m-ATPase and changes in MHC isoform expression was observed. Changes in fraction of active myosin heads, in myosin light chain isoform (MLC) distribution or in MLC phosphorylation, could not explain the variations in m-ATPase. Myosin posttranslational modifications or changes in other myofibrillar proteins may therefore be responsible for the observed variations in m-ATPase activity.
Keywords
Adenosine Triphosphatases/metabolism, Animals, Anoxia/physiopathology, Body Weight/physiology, Calcium/metabolism, Male, Muscle, Skeletal/enzymology, Myofibrils/enzymology, Myosin Heavy Chains/metabolism, Physical Conditioning, Animal/physiology, Physical Endurance/physiology, Rats, Rats, Inbred Strains
Pubmed
Create date
25/09/2008 8:01
Last modification date
20/08/2019 12:58
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