Corticosteroid effects on isotonic contractile properties of rat diaphragm muscle

Roland H.H. Van Balkom, Wen Zhi Zhan, Y. S. Prakash, P. N.Richard Dekhuijzen, Gary C. Sieck

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


The effects of corticosteroids (CS) on diaphragm muscle (Dia(m)) fiber morphology and contractile properties were evaluated in three groups of rats: controls (Ctl), surgical sham and weight-matched controls (Sham), and CS- treated (6 mg · kg-1 · day-1 prednisolone at 2.5 ml/h for 3 wk). In the CS-treated Dia(m), there was a selective atrophy of type IIx and IIb fibers, compared with a generalized atrophy of all fibers in the Sham group. Maximum isometric force was reduced by 20% in the CS group compared with both Ctl and Sham. Maximum shortening velocity in the CS Dia(m) was slowed by ~20% compared with Ctl and Sham. Peak power output of the CS Dia(m) was only 60% of Ctl and 70% of Sham. Endurance to repeated isotonic contractions improved in the CS-treated Dia(m) compared with CtL. We conclude that the atrophy of type IIx and IIb fibers in the Dia(m) can only partially account for the CS- induced changes in isotonic contractile properties. Other factors such as reduced myofibrillar density or altered cross-bridge cycling kinetics are also likely to contribute to the effects of CS treatment.

Original languageEnglish (US)
Pages (from-to)1062-1067
Number of pages6
JournalJournal of applied physiology
Issue number4
StatePublished - Oct 1997


  • Endurance
  • Fatigue
  • Fiber type
  • Prednisolone
  • Shortening velocity
  • Skeletal muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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