Ultra-rapid activation and deactivation of store-operated Ca2+ entry in skeletal muscle

Edwards, Joshua N., Murphy, Robyn M., Cully, Tanya R., von Wegner, Frederic, Friedrich, Oliver and Launikonis, Bradley S. (2010) Ultra-rapid activation and deactivation of store-operated Ca2+ entry in skeletal muscle. Cell Calcium, 47 5: 458-467. doi:10.1016/j.ceca.2010.04.001

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Author Edwards, Joshua N.
Murphy, Robyn M.
Cully, Tanya R.
von Wegner, Frederic
Friedrich, Oliver
Launikonis, Bradley S.
Title Ultra-rapid activation and deactivation of store-operated Ca2+ entry in skeletal muscle
Formatted title
Ultra-rapid activation and deactivation of store-operated Ca2+ entry in skeletal muscle
Journal name Cell Calcium   Check publisher's open access policy
ISSN 0143-4160
1532-1991
Publication date 2010-05
Sub-type Article (original research)
DOI 10.1016/j.ceca.2010.04.001
Volume 47
Issue 5
Start page 458
End page 467
Total pages 10
Place of publication Kidlington, Oxford, United Kingdom
Publisher Churchill Livingstone
Collection year 2011
Language eng
Formatted abstract
Skeletal muscle is highly specialized for the rapid delivery of Ca2+ to the contractile apparatus during excitation-contraction coupling (EC coupling). Previous studies have shown the presence of a relatively fast-activated store-operated Ca2+ entry (SOCE) mechanism (<1s) to be present in skeletal muscle, unlike the situation occurring in non-excitable cells. We simultaneously imaged [Ca2+] in the t-system and cytoplasm in mechanically skinned fibers during SR Ca2+ release and observed both cell-wide Ca2+ release and Ca2+ waves. SOCE activation followed cell-wide Ca2+ release from high sarcoplasmic reticulum (SR) [Ca2+] ([Ca2+]SR) by seconds, consistent with depletion of [Ca2+]SR to an absolute threshold for SOCE and an unformed SOCE complex at high [Ca2+]SR. Ca2+ waves occurred at low [Ca2+]SR, close to the threshold for SOCE, minimizing the time between Ca2+ release and Ca2+ influx. Local activation of SOCE during Ca2+ waves occurred in ∼27ms following local initiation of SR depletion indicating a steep relationship between [Ca2+]SR and SOCE activation. Most of this delay was due to slow release of Ca2+ from SR, leaving only milliseconds at most for the activation of Ca2+ entry following store depletion. SOCE was also observed to deactivate effectively instantly during store refilling at low [Ca2+]SR. These rapid kinetics of SOCE persisted as subsequent Ca2+ waves propagated along the fiber. Thus we show for the first time millisecond activation and deactivation of SOCE during low amplitude [Ca2+]SR oscillations at low [Ca2+]SR. To account for the observed Ca2+ movements we propose the SOCE complex forms during the progressive depletion of [Ca2+]SR prior to reaching the activation threshold of SOCE and this complex remains stable at low [Ca2+]SR.
© 2010 Elsevier Ltd.
Keyword Skeletal muscle
Excitation-contraction coupling
Ryanodine receptor
Store-operated Ca2+ entry
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
School of Biomedical Sciences Publications
 
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Created: Sun, 04 Jul 2010, 00:06:09 EST