Myosin heavy chain composition in young and old rat skeletal muscle: Effects of endurance exercise

V. K. Sullivan, S. K. Powers*, D. S. Criswell, N. Tumer, J. S. Larochelle, D. Lowenthal

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

The objective of this study was to determine the effects of age and exercise on the myosin heavy chain (MHC) composition of skeletal muscle. Young (3 mo) and old (22 mo) female specific pathogen-free barrier-reared Fischer 344 rats were randomly assigned to young untrained or young trained and old untrained or old trained groups, respectively. Young trained and old trained animals performed endurance exercise training on a motorized treadmill for 8 wk. Succinate dehydrogenase activity and MHC isoforms were measured in the plantaris (Plan), lateral and medial gastrocnemius (Gast), and soleus (Sol) muscles. In sedentary animals, aging resulted in a decrease (P < 0.05) in type IIb MHC and an increase (P < 0.05) in type IIa MHC in both the Gast and Plan muscles. Also, aging resulted in a small but significant increase (~4%; P < 0.05) in type I MHC in the Sol. Exercise training resulted in significant (P < 0.05) increases in Gast, Plan, and Sol succinate dehydrogenase activity in both young and old animals. Furthermore, exercise training resulted in a decrease (P < 0.05) in the percentage of type lIb MHC and an increase (P < 0.05) in the percentage of type IIa MHC in the Plan in both young and old animals. These data suggest that there is an age-related shift in locomotor muscle MHC isoforms from a faster to a slower isoform.

Original languageEnglish
Pages (from-to)2115-2120
Number of pages6
JournalJournal of Applied Physiology
Volume78
Issue number6
DOIs
StatePublished - 1995
Externally publishedYes

Keywords

  • Fischer 344 rat
  • fiber type
  • oxidative capacity

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