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

Video 4.
Chaotic, high amplitude calcium fluctuations in the steady state in a 3-D SANC model under voltage clamp at −3 mV, i.e., at a potential at which I_NCX is close to zero and cell calcium is not depleted. 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. P_up = 12 mM/s. See also Fig. 12.