Schneider 1999 recently addressed the question of whether Ca2+ sparks arise from the opening of a single ryanodine receptor (RyR) channel or the simultaneous opening of several channels. The discussion highlighted the importance of single RyR channel permeation and gating in the interpretation of Ca2+ spark data. The Schneider 1999 perspective inspired us to extend this theoretical discussion by using a published kinetic model of modal RyR gating to actually simulate RyR channel gating and permeation that may underlie a Ca2+ spark in cardiac muscle.
Cheng et al. 1993 was the first to propose that the spontaneous Ca2+ spark is the elementary intracellular Ca2+ release unit that underlies excitation–contraction coupling in cardiac muscle. They estimated that the local Ca2+ flux underlying the Ca2+ spark would need to be ∼2 × 10−17...
