Hierarchical clustering of ryanodine receptors enables emergence of a calcium clock in sinoatrial node cells

Video 3.
Local calcium dynamics of a free-running calcium clock in a 3-D SANC model with a random network of RyR clusters simulated immediately after the switch to a voltage clamp at −50 mV, i.e., at a potential close to the onset of the L-type current. With time, LCR events become less synchronous, as cell calcium declines as a result of extrusion of calcium by NCX. The cytosolic [Ca²⁺] is coded by red shades from 100 nM (black) to 5,000 nM (saturation). JSR [Ca²⁺] is coded by a cyan color from 0 (black) to 600 µM (saturation). Calcium dynamics is shown only for the outer shell of cytosolic voxels. k_NCX = 45 pA/pF. See also Fig. 11.