Faculty Collaboration Database

Effects of prolonged space flight on human skeletal muscle enzyme and substrate profiles. J Appl Physiol (1985) 2013 Sep 01;115(5):667-79

Date

06/15/2013

Pubmed ID

23766501

DOI

10.1152/japplphysiol.00489.2013

Scopus ID

2-s2.0-84883595710 (requires institutional sign-in at Scopus site)   45 Citations

Abstract

Our primary goal was to determine the effects of 6-mo flight on the International Space Station (ISS) on selected anaerobic and aerobic enzymes, and the content of glycogen and lipids in slow and fast fibers of the soleus and gastrocnemius. Following local anesthesia, biopsies were obtained from nine ISS crew members ∼45 days preflight and on landing day (R+0) postflight. We subdivided the crew into those who ran 200 min/wk or more (high treadmill, HT) in-flight from those who ran <100 min/wk (low treadmill, LT). In the LT group, there was a loss of lipid in soleus type I fibers, and muscle glycogen significantly increased in soleus fiber types postflight. Soleus cytochrome oxidase (CO) activity was significantly depressed postflight in the type I fiber. This was attributed to the LT group where CO activity was reduced 59%. Otherwise, there was no change in the crew mean for type I or IIa fiber glycolytic or mitochondrial enzyme activities pre- vs. postflight in either muscle. However, two of the three HT subjects (Subjects E and H) showed significant increases in both β-hydroxyacyl-CoA dehydrogenase and citrate synthase in the soleus type I fibers, and Subject E, exhibiting the largest increase in soleus oxidative enzymes, was the only subject to show a significant decrease in glycolytic enzyme activity. It is apparent that crew members performing adequate treadmill running can maintain calf muscle enzymes, which suggests that increased fatigue with weightlessness cannot be directly caused by a decline in muscle enzyme capacity.

Author List

Fitts RH, Colloton PA, Trappe SW, Costill DL, Bain JL, Riley DA

Author

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

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

3-Hydroxyacyl CoA Dehydrogenases
Citrate (si)-Synthase
Exercise
Exercise Test
Glycogen
Humans
Lipids
Muscle Fatigue
Muscle Fibers, Fast-Twitch
Muscle Fibers, Slow-Twitch
Space Flight
Weightlessness