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Growth hormone/IGF-I and/or resistive exercise maintains myonuclear number in hindlimb unweighted musclesIn the present study of rats, we examined the role, during 2 wk of hindlimb suspension, of growth hormone/insulin-like growth factor I (GH/IGF-I) administration and/or brief bouts of resistance exercise in ameliorating the loss of myonuclei in fibers of the soleus muscle that express type I myosin heavy chain. Hindlimb suspension resulted in a significant decrease in mean soleus wet weight that was attenuated either by exercise alone or by exercise plus GH/IGF-I treatment but was not attenuated by hormonal treatment alone. Both mean myonuclear number and mean fiber cross-sectional area (CSA) of fibers expressing type I myosin heavy chain decreased after 2 wk of suspension compared with control (134 vs. 162 myonuclei/mm and 917 vs. 2,076 micron2, respectively). Neither GH/IGF-I treatment nor exercise alone affected myonuclear number or fiber CSA, but the combination of exercise and growth-factor treatment attenuated the decrease in both variables. A significant correlation was found between mean myonuclear number and mean CSA across all groups. Thus GH/IGF-I administration and brief bouts of muscle loading had an interactive effect in attenuating the loss of myonuclei induced by chronic unloading.
Document ID
20040172790
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Allen, D. L.
(University of California Los Angeles, California 94080, United States)
Linderman, J. K.
Roy, R. R.
Grindeland, R. E.
Mukku, V.
Edgerton, V. R.
Date Acquired
August 22, 2013
Publication Date
December 1, 1997
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 83
Issue: 6
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: NS-16333
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center ARC
Non-NASA Center
NASA Discipline Musculoskeletal

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