PF arrhythmias are well known to result from dysfunction of intracellular Ca2+-handling.41 In the present study 6 key Ca2+-handling transcripts were reduced, Cav1.2, Cav1.3, SERCA2a, RyR2, RyR3, and NCX1, in the LPFs in HF (Figures 3 and 5). Here, RYR3 is linked to cardiac arrhythmia.