Figure 4.

Ca²⁺ spark frequency (CaSpF) is higher in control and catecholaminergic polymorphic ventricular tachycardia (CPVT) Purkinje cells (PCs) than in ventricular myocytes (VMs). A, Three-dimensional surface plots of representative line scan images for a CPVT VM and CPVT PC for baseline (left) and 10 nM/L isoproterenol (right). B, Mean CaSpF at 1-, 3-, and 5-Hz stimulation. *P<0.05 vs control VMs at the same pacing frequency. #P<0.05 vs all other cell groups at the same pacing frequency. C, Time course of responses of CPVT VMs and CPVT PCs to isoproterenol (ISO; 10 nmol/L). *P<0.05 in Purkinje CPVT myocytes vs all other cell groups at same time point after isoproterenol.