Cardiac Electrophysiological and Antiarrhythmic Effects of N-n-butyl Haloperidol Iodide

AIMS: N-n-butyl haloperidol (F(2)), a novel compound of quaternary ammonium salt derivatives of haloperidol, was reported to antagonize myocardial ischemia/reperfusion injuries. The antiarrhythmic potential and electrophysiological effects of F(2) on rat cardiac tissues were investigated. METHODS AND RESULTS: In Langendorff-perfused rat hearts, the ventricular arrhythmias were induced by left anterior descending coronary artery of rat heart ligated for 20 min before the release of the ligature. F(2) provided some inhibitive effects against ischemia- and reperfusion-induced ventricular arrhythmias. In His bundle electrogram and epicardial ECG recordings, the drug produced bradycardia, delayed the conduction through the atrioventricular node and prolonged the Wenckebach cycle length and atrioventricular nodal effective refractory period. In whole-cell patch-clamp study, F(2) primarily inhibited the L-type Ca2+ current (I(Ca,L)) (IC(50) = 0.17 microM) with tonic blocking properties and little use-dependence. And the drug also decreased the Na+ current (IC(50) = 77.5 microM), the transient outward K+ current (IC(50) = 20.4 microM), the steady-state outward K+ current (IC(50) = 56.2 microM) and the inward rectifier K+ current (IC(50) = 127.3 microM). CONCLUSION: F(2) may be a promising drug for the treatment of ischemic heart disease with cardiac arrhythmia.