Spontaneous and repetitive calcium transients in C2C12 mouse myotubes during in vitro myogenesis.
Eur J Neurosci
; 9(4): 800-8, 1997 Apr.
Article
em En
| MEDLINE
| ID: mdl-9153587
ABSTRACT
Fluorescence videomicroscopy was used to monitor changes in the cytosolic free Ca2+ concentration ([Ca2+]i) in the mouse muscle cell line C2Cl2 during in vitro myogenesis. Three different patterns of changes in [Ca2+]i were observed (i) [Ca2+]i oscillations; (ii) faster Ca2+ events confined to subcellular regions (localized [Ca2+]i spikes) and (iii) [Ca2+]i spikes detectable in the entire myotube (global [Ca2+]i spikes). [Ca2+]i oscillations and localized [Ca2+]i spikes were detectable following the appearance of caffeine-sensitivity in differentiating C2Cl2 cells. Global [Ca2+]i spikes appeared later in the process of myogenesis in cells exhibiting coupling between voltage-operated Ca2+ channels and ryanodine receptors. In contrast to [Ca2+]i oscillations and localized [Ca2+]i spikes, the global events immediately stopped when cells were perfused either with a Ca2+-free solution, or a solution with TTX, TEA and verapamil. To explore further the mechanism of the global [Ca2+]i spikes, membrane currents and fluorescence signals were measured simultaneously. These experiments revealed that global [Ca2+]i spikes were correlated with an inward current. Moreover, while the depletion of the Ca2+ stores blocked [Ca2+]i oscillations and localized [Ca2+]i spikes, it only reduced the amplitude of global [Ca2+]i spikes. It is suggested that, during the earlier stages of the myogenesis, spontaneous and repetitive [Ca2+]i changes may be based on cytosolic oscillatory mechanisms. The coupling between voltage-operated Ca2+ channels and ryanodine receptors seems to be the prerequisite for the appearance of global [Ca2+]i spikes triggered by a membrane oscillatory mechanism, which characterizes the later phases of the myogenic process.
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Base de dados:
MEDLINE
Assunto principal:
Diferenciação Celular
/
Cálcio
/
Músculo Esquelético
Limite:
Animals
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article