Abstract
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 language | English (US) |
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Pages (from-to) | 1166-1173 |
Number of pages | 8 |
Journal | Journal of applied physiology |
Volume | 84 |
Issue number | 4 |
DOIs | |
State | Published - Apr 1998 |
Keywords
- Fatigue
- Oxidative capacity
- Respiratory muscle
ASJC Scopus subject areas
- Physiology
- Physiology (medical)