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Activity-induced regulation of myosin isoform distribution - Comparison of two contractile activity programsThis study examined the role of specific types of contractile activity in regulating myosin heavy chain (MHC) isoform expression in rodent soleus. A combination of hindlimb suspension (SN) and two programmed contractile training activity paradigms, either isometric contractile activity (ST-IM) or high-load slowly shortening isovelocity activity, were utilized. Both training paradigms increased muscle mass compared with SN alone. However, only ST-IM resulted in a partial prevention of the suspension-induced decrease in type I MHC. With the use of a fluorescently labeled antibody to type IIa MHC, the distribution of MHCs among fibers was examined immunohistochemically. In SN, the percentage of cells staining positive for type IIa MHC was increased but the staining intensity of the positively staining cells was unchanged compared with control cells. In the ST-IM soleus, the percentage of positively staining fibers was unchanged but the intensity of the positively staining cells was decreased compared with SN values. These results suggest that 1) isometric contractile activity is more effective than isovelocity activity in preventing suspension-induced shifts in soleus MHC distribution and 2) changes associated with both suspension and training occur in only a small number of fibers, with the majority of fibers apparently unresponsive to these interventions.
Document ID
19930060186
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Diffee, Gary M.
(NASA Ames Research Center Moffett Field, CA, United States)
Caiozzo, Vince J.
(NASA Ames Research Center Moffett Field, CA, United States)
Mccue, Samuel A.
(NASA Ames Research Center Moffett Field, CA, United States)
Herrick, Robert E.
(NASA Ames Research Center Moffett Field, CA, United States)
Baldwin, Kenneth M.
(California Univ. Irvine, United States)
Date Acquired
August 16, 2013
Publication Date
May 1, 1993
Publication Information
Publication: Journal of Applied Physiology
Volume: 74
Issue: 5
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Accession Number
93A44183
Funding Number(s)
CONTRACT_GRANT: NIH-AR-30346
CONTRACT_GRANT: NAG2-555
Distribution Limits
Public
Copyright
Other

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