Faculty Collaboration Database

Unilateral lower limb suspension does not mimic bed rest or spaceflight effects on human muscle fiber function. J Appl Physiol (1985) 2002 Jul;93(1):354-60

Date

06/19/2002

Pubmed ID

12070225

DOI

10.1152/japplphysiol.01245.2001

Scopus ID

2-s2.0-0035986076 (requires institutional sign-in at Scopus site)   40 Citations

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.

Author List

Widrick JJ, Trappe SW, Romatowski JG, Riley DA, Costill DL, Fitts RH

Author

Robert Fitts PhD Professor in the Biological Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adult
Bed Rest
Calcium
Female
Functional Laterality
Humans
Leg
Male
Muscle Contraction
Muscle Fibers, Skeletal
Muscle Fibers, Slow-Twitch
Muscle, Skeletal
Space Flight
Weightlessness Simulation