Mitochondrial calcium oscillations in C2C12 myotubes.
Details
Serval ID
serval:BIB_19528
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Mitochondrial calcium oscillations in C2C12 myotubes.
Journal
Journal of Biological Chemistry
ISSN
0021-9258
Publication state
Published
Issued date
2001
Volume
276
Number
6
Pages
3791-3797
Language
english
Abstract
Mitochondrial Ca(2+) concentration ([Ca(2+)](m)) was monitored in C2C12 skeletal muscle cells stably expressing the Ca(2+)-sensitive photoprotein aequorin targeted to mitochondria. In myotubes, KCl-induced depolarization caused a peak of 3.03 +/- 0.14 micrometer [Ca(2+)](m) followed by an oscillatory second phase (5.1 +/- 0.1 per min). Chelation of extracellular Ca(2+) or blockade of the voltage-operated Ca(2+) channel attenuated both phases of the KCl response. The inhibitor of the sarcoplasmic reticulum Ca(2+)-ATPase, cyclopiazonic acid, reduced the amplitude of the KCl-induced [Ca(2+)](m) peak and prevented the oscillations, suggesting that these were generated intracellularly. No such [Ca(2+)](m) oscillations occurred with the nicotinic agonist carbachol, cyclopiazonic acid alone, or the purinergic agonist ATP. In contrast, caffeine produced an oscillatory behavior, indicating a role of ryanodine receptors as mediators of the oscillations. The [Ca(2+)](m) response was desensitized when cells were exposed to two consecutive challenges with KCl separated by a 5-min wash, whereas a second pulse of carbachol potentiated [Ca(2+)](m), indicating differences in intracellular Ca(2+) redistribution. Cross-desensitization between KCl and carbachol and cross-potentiation between carbachol and KCl were observed. These results suggest that close contacts between mitochondria and sarcoplasmic reticulum exist permitting Ca(2+) exchanges during KCl depolarization. These newly demonstrated dynamic changes in [Ca(2+)](m) in stimulated skeletal muscle cells might contribute to the understanding of physiological and pathological processes in muscular disorders.
Keywords
Animals, Calcium/metabolism, Cell Line, Mice, Mitochondria/metabolism, Muscle, Skeletal/cytology, Muscle, Skeletal/drug effects, Potassium Chloride/pharmacology
OAI-PMH
Pubmed
Open Access
Yes
Create date
19/11/2007 10:41
Last modification date
20/08/2019 13:50