Store-operated Ca2+ entry during intracellular Ca2+ release in mammalian skeletal muscle

Launikonis, BS and Rios, E (2007) Store-operated Ca2+ entry during intracellular Ca2+ release in mammalian skeletal muscle. Journal of Physiology-london, 583 1: 81-97. doi:10.1113/jphysiol.2007.135046


Author Launikonis, BS
Rios, E
Title Store-operated Ca2+ entry during intracellular Ca2+ release in mammalian skeletal muscle
Journal name Journal of Physiology-london   Check publisher's open access policy
ISSN 0022-3751
Publication date 2007-01-01
Sub-type Article (original research)
DOI 10.1113/jphysiol.2007.135046
Volume 583
Issue 1
Start page 81
End page 97
Total pages 17
Editor Large, WA
Place of publication Oxford
Publisher Blackwell Publishing
Language eng
Subject C1
270602 Animal Physiology - Cell
780105 Biological sciences
Abstract Store-operated Ca2+ entry (SOCE) is activated following the depletion of internal Ca2+ stores in virtually all eukaryotic cells. Shifted excitation and emission ratioing of fluorescence (SEER) was used to image mag-indo-1 trapped in the tubular (t) system of mechanically skinned rat skeletal muscle fibres to measure SOCE during intracellular Ca2+ release. Cytosolic Ca2+ transients were simultaneously imaged using the fluorescence of rhod-2. Spatially and temporally resolved images of t system [Ca2+] ([Ca2+](t-sys)) allowed estimation of Ca2+ entry flux from the rate of decay of [Ca2+]t-sys center dot Ca2+ release was induced pharmacologically to activate SOCE without voltage-dependent contributions to Ca2+ flux. Inward Ca2+ flux was monotonically dependent on the[Ca2+] gradient, and strongly dependent on the transmembrane potential. The activation of SOCE was controlled locally. It could occur without full Ca2+ store depletion and in less than a second after initiation of store depletion. These results indicate that the molecular agonists of SOCE must be evenly distributed throughout the junctional membranes and can activate rapidly. Termination of SOCE required a net increase in [Ca2+]SR. Activation and termination of SOCE are also demonstrated, for the first time, during a single event of Ca2+ release. At the physiological [Ca2+](t-sys), near 2 mm (relative to t system volume), SOCE flux relative to accessible cytoplasmic volume was at least 18.6 mu M s(-1), consistent with times of SR refilling of 1-2 min measured in intact muscle fibres.
Keyword Physiology
Transverse Tubular System
Sarcoplasmic-reticulum
Calcium-release
Plasma-membrane
Ryanodine Receptor
Twitch Fibers
Frog-muscle
Rat
Excitation
Toad
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Tue, 19 Feb 2008, 00:56:11 EST