Dantrolene is thought to act by reinforcing the action of calmodulin (CaM) in stabilizing the interaction between the N-terminus and central domains of both RyR1 and RyR2, as suggested by the unzipping model of arrhythmogenesis in CPVT (Figure 2B). Here, RYR1 is linked to catecholaminergic polymorphic ventricular tachycardia.