Description of modal gating of the cardiac calcium release channel in planar lipid membranes

Biophys J. 1995 Nov;69(5):1780-8. doi: 10.1016/S0006-3495(95)80048-2.


Single channel activity of the cardiac ryanodine-sensitive calcium-release channel in planar lipid membranes was studied in order to elucidate the calcium-dependent mechanism of its steady-state behavior. The single channel kinetics, observed with Cs+ as the charge carrier at different activating (cis) Ca2+ concentrations in the absence of ATP and Mg2+, were similar to earlier reports and were extended by analysis of channel modal behavior. The channel displayed three episodic levels of open probability defining three gating modes: H (high activity), L (low activity), and I (no activity). The large difference in open probabilities between the two active modes resulted from different bursting patterns and different proportions of two distinct channel open states. I-mode was without openings and can be regarded as the inactivated mode of the channel; L-mode was composed of short and sparse openings; and H-mode openings were longer and grouped into bursts. Modal gating may explain calcium-release channel adaptation (as transient prevalence of H-mode after Ca2+ binding) and the inhibitory effects of drugs (as stabilization of mode I), and it provides a basis for understanding the regulation of calcium release.

MeSH terms

  • Adaptation, Physiological
  • Animals
  • Biophysical Phenomena
  • Biophysics
  • Calcium / metabolism
  • Calcium Channels / metabolism*
  • Dogs
  • In Vitro Techniques
  • Ion Channel Gating / physiology*
  • Kinetics
  • Membrane Lipids / metabolism*
  • Muscle Proteins / metabolism*
  • Myocardium / metabolism*
  • Ryanodine Receptor Calcium Release Channel


  • Calcium Channels
  • Membrane Lipids
  • Muscle Proteins
  • Ryanodine Receptor Calcium Release Channel
  • Calcium