Fig 5. SAN cells synchronize their electrical properties when coupled in a tissue.

(A) When coupled together heterogeneous SAN cells give rise to a spontaneously beating tissue. The only exception occurs at very high values of heterogeneity (σ equal to 0.4 and 0.5, with 0.5% and 2.8% of dormant cells respectively) and very high levels of intercellular resistance (R = 10,000 MΩ). (B-D) The population of cells synchronizes its AP metrics: cycle length (CL), action potential amplitude (APA) and action potential duration (APD) when well-connected in tissue.