Spontaneous and repetitive calcium transients in C2C12 mouse myotubes during in vitro myogenesis

Eur J Neurosci. 1997 Apr;9(4):800-8. doi: 10.1111/j.1460-9568.1997.tb01429.x.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
  • Adenosine Triphosphate / pharmacology
  • Animals
  • Apamin / pharmacology
  • Caffeine / pharmacology
  • Calcium / metabolism*
  • Cell Differentiation* / drug effects
  • Cell Line
  • Cytosol / metabolism
  • Egtazic Acid / pharmacology
  • Kinetics
  • Membrane Potentials / drug effects
  • Mice
  • Microscopy, Confocal
  • Microscopy, Video
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / physiology*
  • Oscillometry
  • Potassium Chloride / pharmacology
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology
  • Tetrodotoxin / pharmacology
  • Verapamil / pharmacology

Substances

  • Tetraethylammonium Compounds
  • Apamin
  • Caffeine
  • Tetrodotoxin
  • Egtazic Acid
  • Tetraethylammonium
  • Potassium Chloride
  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Adenosine Triphosphate
  • Verapamil
  • Calcium

Grant support