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This Article Full Text Full Text (PDF) All Versions of this Article: 580/3/993    most recent jphysiol.2006.127464v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rose, A. J. Articles by Richter, E. A. Search for Related Content PubMed PubMed Citation Articles by Rose, A. J. Articles by Richter, E. A. Related Collections Skeletal Muscle and Exercise

¹ Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Universitetsparken 13, Copenhagen, Denmark, 2100

The activation and function of Ca²⁺–calmodulin-dependent kinase II (CaMKII) in contracting rat skeletal muscle was examined. The increase in autonomous activity and phosphorylation at Thr²⁸⁷ of CaMKII of gastrocnemius muscle in response to contractions in situ was rapid and transient, peaking at 1–3 min, but reversed after 30 min of contractions. There was a positive correlation between CaMKII phosphorylation at Thr²⁸⁷ and autonomous CaMKII activity. In contrast to the rapid and transient increase in autonomous CaMKII activity, the phosphorylation of the putative CaMKII substrate trisk95/triadin was rapid and sustained during contractions. There were no changes in CaMKII activity and phosphorylation or trisk95 phosphorylation in the resting contralateral muscles during stimulation. When fast-twitch muscles were contracted ex vivo, CaMKII inhibition resulted in a greater magnitude of fatigue as well as blunted CaMKII and trisk95 phosphorylation, identifying trisk95 as a physiological CaMKII substrate. In summary, skeletal muscle CaMKII activation was rapid and sustained during exercise/contraction and is mediated by factors within the contracting muscle, probably through allosteric activation via Ca²⁺–CaM. CaMKII may signal through trisk95 to modulate Ca²⁺ release in fast-twitch rat skeletal muscle during exercise/contraction.

(Received 23 December 2006; accepted after revision 1 February 2007; first published online 1 February 2007)
Corresponding author A. J. Rose: Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Universitetsparken 13, Copenhagen, Denmark, 2100. Email: arose{at}ifi.ku.dk