Recent clinical studies show that pulmonary veins (PVs) are important foci of atrial tachyarrhythmias. Autonomic nervous system was known to play a role in the genesis of atrial tachyarrhythmias. The present experiments aimed to investigate the actions of autonomic agents in dog PVs and to explore the arrhythmogenic activity in these tissues. Transmembrane action potentials were recorded with the conventional microelectrode techniques and tension was detected by a transducer. In PV driven electrically, isoproterenol (Isop, 1μM) increased while ACh (1-10μM) depressed twitch force but elevated resting tension. In PV active spontaneously, Isop increased the automatic rate and induced high frequency irregular rhythms while ACh suppressed them. The actions of Isop and ACh were antagonized by propranolol and atropine, respectively. Quite often a single microelectrode impalement recorded 2 and more types of action potentials with wide range of durations (APD), indicating presence of multiple cells with different electrophysiological properties and electrical uncoupling of neighboring cells in PV strips. Activation of β-adrenoceptor stimulated while cholinergic agonist suppressed spontaneous action potentials or high frequency irregular rhythms in PV.