Faculty Collaboration Database

Effect of hindlimb unweighting on single soleus fiber maximal shortening velocity and ATPase activity. J Appl Physiol (1985) 1993 Jun;74(6):2949-57

Date

06/01/1993

Pubmed ID

8365995

DOI

10.1152/jappl.1993.74.6.2949

Scopus ID

2-s2.0-0027213241 (requires institutional sign-in at Scopus site)   48 Citations

Abstract

This study characterizes the time course of change in single soleus muscle fiber size and function elicited by hindlimb unweighting (HU) and analyzes the extent to which varying durations of HU altered maximal velocity of shortening (Vo), myofibrillar adenosinetriphosphatase (ATPase), and relative content of slow and fast myosin in individual soleus fibers. After 1, 2, or 3 wk of HU, soleus muscle bundles were prepared and stored in skinning solution at -20 degrees C. Single fibers were isolated and mounted between a motor arm and a transducer, and fiber force, Vo, and ATPase activity were measured. Fiber myosin content was determined by one-dimensional sodium dodecyl sulfate- (SDS) polyacrylamide gel electrophoresis. After 1, 2, and 3 wk of HU, soleus fibers exhibited a progressive reduction in fiber diameter (16, 22, and 42%, respectively) and peak force (42, 48, and 72%, respectively). Peak specific tension was significantly reduced after 1 wk of HU (18%) and showed no further change in 2-3 wk of HU. During 1 and 3 wk of HU, fiber Vo and ATPase showed a significant increase. By 3 wk, Vo had increased from 1.32 +/- 0.04 to 2.94 +/- 0.17 fiber lengths/s and fiber ATPase from 291 +/- 16 to 1,064 +/- 128 microM.min-1 x mm-3. The percent fibers expressing fast myosin heavy chain increased from 4% to 29% by 3 wk of HU, and Vo and ATPase activity within a fiber were highly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

McDonald KS, 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

Adenosine Triphosphatases
Animals
Hindlimb
Male
Muscle Contraction
Muscles
Muscular Atrophy
Myosins
Rats
Rats, Sprague-Dawley
Time Factors
Weightlessness