Superoxide, hydroxyl radical, and hydrogen peroxide effects on single-diaphragm fiber contractile apparatus

L. A. Callahan, Z. W. She, T. M. Nosek

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Reactive oxygen species contribute to diaphragm dysfunction in certain pathophysiological conditions (i.e., sepsis and fatigue). However, the precise alterations induced by reactive oxygen species or the specific species that are responsible for the derangements in skeletal muscle function are incompletely understood. In this study, we evaluated the effect of the superoxide anion radical (O2/-·), hydroxyl radical (·OH), and hydrogen peroxide (H2O2) on maximum calcium-activated force (Fmax) and calcium sensitivity of the contractile apparatus in chemically skinned (Triton X-100) single rat diaphragm fibers. O2/-· was generated using the xanthine/xanthine oxidase system; ·OH was generated using 1 mM FeCl2, 1 mM ascorbate, and 1 mM H2O2; and H2O2 was added directly to the bathing medium. Exposure to O2/-· or ·OH significantly decreased Fmax by 14.5% (P < 0.05) and 43.9% (P < 0.005), respectively. ·OH had no effect on Ca2+ sensitivity. Neither 10 nor 1,000 μM H2O2 significantly altered Fmax or Ca2+ sensitivity. We conclude that the diaphragm is susceptible to alterations induced by a direct effect of ·OH and O2/-·, but not H2O2, on the contractile proteins, which could, in part, be responsible for prolonged depression in contractility associated with respiratory muscle dysfunction in certain pathophysiological conditions.

Original languageEnglish
Pages (from-to)45-54
Number of pages10
JournalJournal of Applied Physiology
Issue number1
StatePublished - 2001


  • Free radicals
  • Reactive oxygen species
  • Respiratory muscle
  • Skeletal muscle
  • Skinned muscle fibers

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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