Hypoxemia-induced modification of troponin I and T in canine diaphragm

Jeremy A. Simpson, Jennifer E. Van Eyk, Steve Iscoe

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Impaired muscle function (fatigue) may result, in part, from modification of contractile proteins due to inadequate O2 delivery. We hypothesized that severe hypoxemia would modify skeletal troponin I (TnI) and T (TnT), two regulatory contractile proteins, in respiratory muscles. Severe isocapnic hypoxemia (arterial partial pressure of O2 of ~25 Torr) in six pentobarbital sodium-anesthetized spontaneously breathing dogs increased respiratory frequency and electromyographic activity of the diaphragm and internal and external obliques, with death occurring after 131-285 min. Western blot analysis revealed proteolyis of TnI and TnT, 17.5- and 28-kDa fragments, respectively, and higher molecular mass covalent complexes, one of which (42 kDa) contained TnI (or some fragment of it) and probably TnT in the costal and crural diaphragms but not the intercostal or abdominal muscles. These modifications of myofibrillar proteins may provide a molecular basis for contractile dysfunction, including respiratory failure, under conditions of limited O2 delivery.

Original languageEnglish (US)
Pages (from-to)753-760
Number of pages8
JournalJournal of applied physiology
Issue number2
StatePublished - Feb 2000
Externally publishedYes


  • Contractile proteins
  • Protein degradation
  • Protein modification
  • Respiratory failure
  • Respiratory muscles

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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