The elusive role of store depletion in the control of intracellular calcium release

Rios, E., Launikonis, B. S., Royer, L., Brum, G. and Zhou, J (2006) The elusive role of store depletion in the control of intracellular calcium release. Journal of Muscle Research And Cell Motility, 27 5-7: 337-350. doi:10.1007/s10974-006-9082-5


Author Rios, E.
Launikonis, B. S.
Royer, L.
Brum, G.
Zhou, J
Title The elusive role of store depletion in the control of intracellular calcium release
Journal name Journal of Muscle Research And Cell Motility   Check publisher's open access policy
ISSN 0142-4319
1573-2657
Publication date 2006-05-01
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1007/s10974-006-9082-5
Volume 27
Issue 5-7
Start page 337
End page 350
Total pages 14
Place of publication Netherlands
Publisher Springer
Language eng
Abstract The contractile cycle of striated muscles, skeletal and cardiac, is controlled by a cytosolic [Ca2+] transient that requires rapid movements of the ion through channels in the sarcoplasmic reticulum (SR). A functional signature of these channels is their closure after a stereotyped time lapse of Ca2+ release. In cardiac muscle there is abundant evidence that termination of release is mediated by depletion of the Ca2+ store, even if the linkage mechanism remains unknown. By contrast, in skeletal muscle the mechanisms of release termination are not understood. This article reviews measurements of store depletion, the experimental evidence for dependence of Ca2+ release on the [Ca2+] level inside the SR, as well as tests of the molecular nature of putative intra-store Ca2+ sensors. Because Ca2+ sparks exhibit the basic release termination mechanism, much attention is dedicated to the studies of store depletion caused by sparks and its relationship with termination of sparks. The review notes the striking differences in volume, content and buffering power of the stores in cardiac vs. skeletal muscle, differences that explain why functional depletion is much greater for cardiac than skeletal muscle stores. Because in skeletal muscle store depletion is minimal and reduction in store [Ca2+] does not appear to greatly inhibit Ca2+ release, it is concluded that decrease in free SR [Ca2+] does not mediate physiological termination of Ca2+ release in this type of muscle. In spite of the apparent absence of store depletion and its putative channel closing effect, termination of Ca2+ sparks is faster and more robust in skeletal than cardiac muscle. A gating role of a hypothetical "proximate store" constituted by polymers of calsequestrin and associated proteins is invoked in an attempt to preserve a role for store depletion and unify mechanisms in both types of striated muscle.
Keyword Cell Biology
skeletal muscle
cardiac muscle
sarcoplasmic reticulum
calcium sparks
calsequestrin
Skeletal-muscle Fibers
Sarcoplasmic-reticulum Calcium
Rat Ventricular Myocytes
20 Mm Egta
Ca2+ Release
Ryanodine-receptor
Mammalian Muscle
Luminal Calcium
Elementary Events
Cardiac Myocytes
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown
Additional Notes This document is a journal review.

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Excellence in Research Australia (ERA) - Collection
School of Biomedical Sciences Publications
 
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Created: Thu, 20 Sep 2007, 04:59:15 EST