Faculty Collaboration Database

Force-velocity and power characteristics of rat soleus muscle fibers after hindlimb suspension. J Appl Physiol (1985) 1994 Oct;77(4):1609-16

Date

10/01/1994

Pubmed ID

7836176

DOI

10.1152/jappl.1994.77.4.1609

Scopus ID

2-s2.0-0027997832 (requires institutional sign-in at Scopus site)   59 Citations

Abstract

The 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 HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 degrees 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 and 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 (Vo), but myosin heavy chain remained entirely slow type I. The mechanism for increased Vo is unknown. There was a progressive decrease in fiber diameter (14, 30, and 38%) and peak force (38, 56, and 63%) 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 Vo was higher than control at all relative loads < 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

McDonald KS, Blaser CA, 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

Animals
Electrophoresis, Polyacrylamide Gel
Male
Microcomputers
Muscle Contraction
Muscle Fibers, Fast-Twitch
Muscle Fibers, Slow-Twitch
Muscle, Skeletal
Myosins
Random Allocation
Rats
Rats, Sprague-Dawley
Weightlessness