Ca2Â +/calmodulin-activated phosphodiesterase 1A is highly expressed in rabbit cardiac sinoatrial nodal cells and regulates pacemaker function

We conclude that signaling via cAMP generated by Ca2 +/CaM-activated AC in SANC lipid raft domains is limited by cAMP degradation by Ca2 +/CaM-activated PDE1A in non-lipid raft domains. This suggests that local gradients of [Ca2 +]-CaM or different AC and PDE1A affinity regulate both cAMP production and its degradation, and this balance determines the intensity of Ca2 +-AC-cAMP-PKA signaling that drives SANC pacemaker function.