Antiarrhythmic effects of nebivolol in experimental models in vivo

Antiarrhythmic effects of nebivolol, a cardioselective beta 1-adrenoceptor blocker facilitating vascular release of nitric oxide (NO), were investigated in different experimental models. In the reperfusion-induced arrhythmias after 5 min of left coronary artery ligation in rats, nebivolol 1.25 mg/kg intravenously (i.v.) reduced the incidence of ventricular tachycardia (VT) from 85% in the solvent group to 33% (p < 0.05) and decreased that of ventricular fibrillation (VF) to 20% vs. 67% in the solvent group, (p < 0.05). In ischemia-induced arrhythmias resulting from 20-min coronary artery ligation in rats, nebivolol 1.25 mg/kg i.v. reduced the incidence of VT to 50% as compared with 87% in the solvent group and decreased the incidence of VF to 17% as compared with 67% in the solvent group (p < 0.05). In electrically stimulated hearts in open-chest guinea pigs, nebivolol produced a dose-dependent (0.16-2.5 mg/kg i.v.) increase in VF threshold (VFT). In guinea pigs with ouabain-induced cardiotoxicity, nebivolol 1.25 mg/kg i.v. (n = 7) doubled the doses of ouabain required to provoke toxic ECG changes as compared with those in the solvent-pretreated group. In rats with aconitine-induced cardiac toxicity, nebivolol 1.25 mg/kg i.v. significantly reduced the incidence of ventricular arrhythmias. Our results demonstrate that nebivolol suppresses arrhythmias in various experimental models in vivo.