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Updated: Jun 21, 2026
Myo-mechanical Analysis of Isolated Skeletal Muscle
Published on: February 23, 2011
Skeletal muscles of mice deficient in muscle creatine kinase lack burst activity
J van Deursen1, A Heerschap, F Oerlemans
1Department of Cell Biology and Histology, Faculty of Medical Sciences, University of Nijmegen, The Netherlands.
Abstract:
To understand the physiological role of the creatine kinase-phosphocreatine (CK-PCr) system in muscle bioenergetics, a null mutation of the muscle CK (M-CK) gene was introduced into the germline of mice. Mutant mice show no alterations in absolute muscle force, but lack the ability to perform burst activity. Their fast-twitch fibers have an increased intermyofibrillar mitochondrial volume and an increased glycogenolytic/glycolytic potential. PCr and ATP levels are normal in resting M-CK-deficient muscles, but rates of high energy phosphate exchange between PCr and ATP are at least 20-fold reduced. Strikingly, PCr levels decline normally during muscle exercise, suggesting that M-CK-mediated conversion is not the only route for PCr utilization in active muscle.
Insights
Mice lacking the muscle creatine kinase (CK) gene cannot perform burst activity, despite normal energy levels. This suggests alternative pathways exist for energy utilization in active muscles.
Area of Science:
- Muscle physiology
- Bioenergetics
- Biochemistry
Background:
- The creatine kinase-phosphocreatine (CK-PCr) system is crucial for rapid energy buffering in muscle.
- Understanding its precise physiological role requires investigating conditions with impaired function.
Purpose of the Study:
- To elucidate the physiological significance of the CK-PCr system in muscle bioenergetics.
- To investigate the functional consequences of a null mutation in the muscle creatine kinase (M-CK) gene.
Main Methods:
- Generation of germline M-CK gene-null mutant mice.
- Assessment of muscle force, contractile properties, and fiber type characteristics.
- Analysis of high-energy phosphate levels (PCr, ATP) and energy exchange rates during rest and exercise.
Main Results:
- M-CK-deficient mice exhibited normal absolute muscle force but impaired burst activity performance.
- Fast-twitch muscle fibers showed increased mitochondrial volume and enhanced glycogenolytic/glycolytic capacity.
- While resting PCr and ATP levels were normal, the rate of PCr-ATP exchange was significantly reduced (at least 20-fold).
- PCr levels decreased during exercise, indicating M-CK-independent utilization pathways.
Conclusions:
- The M-CK enzyme is essential for efficient high-energy phosphate transfer during intense muscle activity.
- Muscle bioenergetics can adapt to M-CK deficiency through increased mitochondrial and glycolytic capacity.
- Alternative pathways contribute to phosphocreatine utilization in exercising muscle, independent of M-CK-mediated buffering.
