Faculty Collaboration Database

Spaceflight effects on single skeletal muscle fiber function in the rhesus monkey. Am J Physiol Regul Integr Comp Physiol 2000 Nov;279(5):R1546-57

Date

10/26/2000

Pubmed ID

11049835

DOI

10.1152/ajpregu.2000.279.5.R1546

Scopus ID

2-s2.0-0033668502 (requires institutional sign-in at Scopus site)   26 Citations

Abstract

The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 +/- 1, 46 +/- 2, and 59 +/- 2 microm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 +/- 0.01 to 0.31 +/- 0.02 (CS group) and 0.32 +/- 0.01 mN (SF group). When the peak force was expressed as kiloNewtons per square meter (kN/m(2)), only the SF group showed a significant decline. This group also showed a significant 15% drop in peak fiber stiffness that suggests that fewer cross bridges were contracting in parallel. In the MG, SF but not CS depressed the type I fiber diameter and force. Additionally, SF significantly depressed absolute (mN) and relative (kN/m(2)) force in the fast-twitch MG fibers by 30% and 28%, respectively. The Ca(2+) sensitivity of the type I fiber (Sol and MG) was significantly reduced by growth but unaltered by SF. Flight had no significant effect on the mean maximal fiber shortening velocity in any fiber type or muscle. The post-SF Sol type I fibers showed a reduced peak power and, at peak power, an elevated velocity and decreased force. In conclusion, CS and SF caused atrophy and a reduced force and power in the Sol type I fiber. However, only SF elicited atrophy and reduced force (mN) in the MG type I fiber and a decline in relative force (kN/m(2)) in the Sol type I and MG type II fibers.

Author List

Fitts RH, Desplanches D, Romatowski JG, Widrick JJ

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
Biomechanical Phenomena
Body Weight
Calcium
Isotonic Contraction
Macaca mulatta
Male
Microscopy, Electron
Muscle Contraction
Muscle Fibers, Fast-Twitch
Muscle Fibers, Slow-Twitch
Muscle, Skeletal
Space Flight
Weightlessness