Absence of myofibrillar creatine kinase and diaphragm isometric function during repetitive activation

John J. Labella, Monica J. Daood, A. P. Koretsky, Brian B. Roman, Gary C. Sieck, Be Wieringa, Jon F. Watchko

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Creatine kinase (CK) provides ATP buffering in skeletal muscle and is expressed as 1) cytosolic myofibrillar CK (M-CK) and 2) sarcomeric mitochondrial CK (ScCKmit) isoforms that differ in their subcellular localization. We compared the isometric contractile and fatigue properties of 1) control CK-sufficient (Ctl), 2) M-CK-deficient (M-CK[-/-]), and 3) combined M-CK/ScCKmit-deficient null mutant (CK[-/-])diaphragm (Dia) to determine the effect of the absence of M-CK activity on Dia performance in vitro. Baseline contractile properties were comparable across groups except for specific force, which was ~16% lower in CK[-/-] Dia compared with M- CK[-/-] and Ctl Dia. During repetitive activation (40 Hz, 1/3 duty cycle), force declined in all three groups. This decline was significantly greater in CK[-/-] Dia compared with Ctl and M-CK[-/-] Dia. The pattern of force decline did not differ between M-CK[-/-] and Ctl Dia. We conclude that Dia isometric muscle function is not absolutely dependent on the presence of M-CK, whereas the complete absence of CK acutely impairs isometric force generation during repetitive activation.

Original languageEnglish (US)
Pages (from-to)1166-1173
Number of pages8
JournalJournal of applied physiology
Issue number4
StatePublished - Apr 1998


  • Fatigue
  • Oxidative capacity
  • Respiratory muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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