Arrhythmogenic coupling between the Na+-Ca2Â + exchanger and inositol 1,4,5-triphosphate receptor in rat pulmonary vein cardiomyocytes

► NE induces spontaneous activity in isolated PV cardiomyocytes. ► Morphological and electrophysiological properties differ between PV and LA myocytes. ► Both a1 and b1-receptor stimulations are required for NE-induced automaticity. ► Release of Ca2 + via IP3R activates NCX to cause automaticity. ► T-tubule system is enriched in PV cardiomyocytes, in contrast to atrial cells.