As previously reported26,27, wild-type mice are relatively insensitive to the administration of caffeine and adrenaline, whereas arrhythmia-prone mice, such as those carrying mutation or deletion of the ryanodine receptor (Ryr2) or calsequestrin (Casq2) genes, progress rapidly to bidirectional ventricular tachycardia (BVT). Here, RYR2 is linked to cardiac arrhythmia.