Concerted vs. sequential. Two activation patterns of vast arrays of intracellular Ca2+ channels in muscle

Zhou, Jin Song, Brum, Gustavo, Gonzalez, Adom, Launikonis, Bradley S., Stern, Michael D. and Rios, Eduardo (2005) Concerted vs. sequential. Two activation patterns of vast arrays of intracellular Ca2+ channels in muscle. Journal of General Physiology, 126 4: 301-309. doi:10.1085/jgp.200509353

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Author Zhou, Jin Song
Brum, Gustavo
Gonzalez, Adom
Launikonis, Bradley S.
Stern, Michael D.
Rios, Eduardo
Title Concerted vs. sequential. Two activation patterns of vast arrays of intracellular Ca2+ channels in muscle
Journal name Journal of General Physiology   Check publisher's open access policy
ISSN 0022-1295
Publication date 2005-10
Sub-type Article (original research)
DOI 10.1085/jgp.200509353
Open Access Status File (Publisher version)
Volume 126
Issue 4
Start page 301
End page 309
Total pages 9
Place of publication New York
Publisher Rockefeller University Press
Language eng
Abstract To signal cell responses, Ca2+ is released from storage through intracellular Ca2+ channels. Unlike most plasmalemmal channels, these are clustered in quasi-crystalline arrays, which should endow them with unique properties. Two distinct patterns of local activation of Ca2+ release were revealed in images of Ca2+ sparks in permeabilized cells of amphibian muscle. In the presence of sulfate, an anion that enters the SR and precipitates Ca2+, sparks became wider than in the conventional, glutamate-based solution. Some of these were "protoplatykurtic" (had a flat top from early on), suggesting an extensive array of channels that activate simultaneously. Under these conditions the rate of production of signal mass was roughly constant during the rise time of the spark and could be as high as 5 mu m(3) ms(-1), consistent with a release current >50 pA since the beginning of the event. This pattern, called "concerted activation," was observed also in rat muscle fibers. When sulfate was combined with a reduced cytosolic [Ca2+] (50 nM) these sparks coexisted (and interfered) with a sequential progression of channel opening, probably mediated by Ca2+-induced Ca2+ release (CICR). Sequential propagation, observed only in frogs, may require parajunctional channels, of RyR isoform beta, which are absent in the rat. Concerted opening instead appears to be a property of RyR alpha in the amphibian and the homologous isoform 1 in the mammal.
Keyword Physiology
Frog Skeletal-muscle
Calcium-release Channels
Mammalian Muscle
Ryanodine Receptors
Elementary Events
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Biomedical Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 17 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 19 Sep 2007, 19:14:28 EST