Unilateral Lower Limb Suspension Does Not Mimic Bed Rest or Spaceflight Effects on Human Muscle Fiber Function
Document Type
Article
Language
eng
Format of Original
7 p.
Publication Date
7-2002
Publisher
American Physiological Society
Source Publication
Journal of Applied Physiology
Source ISSN
0021-8987
Abstract
We used Ca2+-activated skinned muscle fibers to test the hypothesis that unilateral lower leg suspension (ULLS) alters cross-bridge mechanisms of muscle contraction. Soleus and gastrocnemius biopsies were obtained from eight subjects before ULLS, immediately after 12 days of ULLS (post-0 h), and after 6 h of reambulation (post-6 h). Post-0 h soleus fibers expressing type I myosin heavy chain (MHC) showed significant reductions in diameter, absolute and specific peak Ca2+-activated force, unloaded shortening velocity, and absolute and normalized peak power. Fibers obtained from the gastrocnemius were less affected by ULLS, particularly fibers expressing fast MHC isoforms. Post-6 h soleus fibers produced less absolute and specific peak force than did post-0 h fibers, suggesting that reambulation after ULLS induced cell damage. Like bed rest and spaceflight, ULLS primarily affects soleus over gastrocnemius fibers. However, in contrast to these other models, slow soleus fibers obtained after ULLS showed a decrease in unloaded shortening velocity and a greater reduction in specific force.
Recommended Citation
Widrick, Jeffrey J.; Trappe, S. W.; Romatowski, Janell; Riley, Danny A.; Costill, David; and Fitts, Robert, "Unilateral Lower Limb Suspension Does Not Mimic Bed Rest or Spaceflight Effects on Human Muscle Fiber Function" (2002). Biological Sciences Faculty Research and Publications. 34.
https://epublications.marquette.edu/bio_fac/34
Comments
Journal of Applied Physiology, Vol. 93, No. 1 (July 2002): 354-360. DOI.
Janell Romatowski was affiliated with Ball State University at the time of publication.