Effect of βAR stimulation wanes as disorder in CRU positions increases. Shown are CL intervalograms for simulations of AP firing in basal state (blue plots) and in the presence of βAR stimulation (red plots). Note: βAR stimulation shortens the CLs towards about the same level within a narrow range of 291–266 ms, i.e., βAR stimulation unifies spontaneous AP firing towards a higher common rate. All simulations started from the identical initial conditions.