['To examine the effect of landiolol (ONO-1101), a new ultra-short acting and highly selective beta blocker, on epinephrine-induced ventricular arrhythmias in halothane-anesthetized dogs.', 'We administered five different doses (0, 0.1, 0.5, 1.0, 10 microg x kg(-1) x min(-1)) landiolol and determined the dysrhythmogenic dose of epinephrine (DDE), defined as the smallest dose producing four or more PVCs within 15 sec, at each dose of landiolol and after cessation of infusion.', 'The control value of DDE during 1.3 MAC halothane anesthesia was 1.26 +/- 0.44 (mean +/- SD) microg x kg(-1) x min(-1) and the corresponding plasma concentration of epinephrine (PCE) was 12.2 +/- 8.3 ng x ml(-1). Concomitant administration of 10 microg x kg(-1) x min(-1) landiolol increased DDE and corresponding PCE (P < 0.05). At 30 min after cessation of landiolol infusion, DDE and corresponding PCE returned to the control values.'] Does landiolol decrease a dysrhythmogenic dose of epinephrine in dogs during halothane anesthesia?