Functional properties and [Ca(2+)](i) metabolism of creatine kinase--KO mice myocardium.
One major function of the creatine kinase system is to maintain energy demand of myofibrillar contraction processes. Loss of the CK-system led to adaptations in skeletal muscle. To analyze the impact on myocardial function contractile parameters and intracellular calcium metabolism of transgenic mice lacking mitochondrial CK (ScCKmit(-/-)) alone or both mitochondrial and cytoplasmic ScCK (CK(-/-)) were investigated compared to wild type at various workload conditions using isolated intact muscle fibers. Force development at baseline conditions, force-frequency relationship (60-600/min), and rapid frequency switch (60-600/min) were unaltered in myocardium of transgenic mice compared to wild type. Intracellular calcium metabolism revealed unchanged amplitude of the intracellular calcium transients (ICT), refilling of the sarcoplasmic reticulum (calcium reuptake, post-rest behavior) in the ScCKmit(-/-) and CK(-/-) mice. The results demonstrate the effectiveness of myocardial energy-recruiting compensatory mechanisms at baseline as well as under stress conditions in CK depleted myocardium of transgenic mice.
Bonz
Andreas W
AW
Department of Cardiology, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany. a.bonz@medizin.uni-wuerzburg.de
Kniesch
Silke
S
Hofmann
Ulrich
U
Küllmer
Sina
S
Bauer
Lisa
L
Wagner
Helga
H
Ertl
Georg
G
Spindler
Matthias
M
D000222:Adaptation, Physiological; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003402:Creatine Kinase / Q000235:genetics*; D052279:Creatine Kinase, MB Form; D052281:Creatine Kinase, Mitochondrial Form; D046508:Culture Techniques; D004558:Electric Stimulation; D007527:Isoenzymes / Q000235:genetics*; D007537:Isometric Contraction; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology; D009126:Muscle Relaxation; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*
D007527:Isoenzymes; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form; D052281:Creatine Kinase, Mitochondrial Form; D002118:Calcium