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Force-velocity and power characteristics of rat soleus muscle fibers after hindlimb suspensionThe effects of 1, 2, and 3 wk of hindlimb suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HA, small fiber bundles were isolated, placed in skinning solution, and stored at -20 C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type II fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (V sub O)), but myosin heavy chain remained entirely slow type I. The mechanism for increased V(sub O) is unknown. There was a progressive decrease in fiber diameter and peak force after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that V(sub O) was higher than control at all relative loads less than 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk. The results suggest that between 2 and 3 wk the HS-induced alterations in the force-velocity relationship act to maintain the power output of single soleus fibers despite a continued reduction in fiber force.
Document ID
19950042737
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Mcdonald, K. S.
(Marquette Univ. Milwaukee, WI, United States)
Blaser, C. A.
(Marquette Univ. Milwaukee, WI, United States)
Fitts, R. H.
(Marquette Univ. Milwaukee, WI, United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1994
Publication Information
Publication: Journal of Applied Physiology
Volume: 77
Issue: 4
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Accession Number
95A74336
Funding Number(s)
CONTRACT_GRANT: NAS2-212
Distribution Limits
Public
Copyright
Other

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