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J Cardiovasc Pharmacol. 2014 May;63(5):421-7. doi: 10.1097/FJC.0000000000000065.

Effects of the selective KACh channel blocker NTC-801 on atrial fibrillation in a canine model of atrial tachypacing: comparison with class Ic and III drugs.

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  • 1*Pharmaceutical Development Research Laboratories, Teijin Institute for Bio-Medical Research, Teijin Pharma Limited, Tokyo, Japan; †Pharmaceutical Research Department, Biological Research Laboratories, Nissan Chemical Industries, Ltd, Saitama, Japan; ‡Department of Cardiology, Keio University School of Medicine, Tokyo, Japan; §Department of Pharmacology, Chiba University Graduate School of Medicine, Chiba, Japan; and ¶Mita Hospital, International University of Health and Welfare, Tokyo, Japan.


The present study examines the effects of NTC-801, a highly selective acetylcholine (ACh) receptor-activated potassium (KACh) channel blocker, on atrial fibrillation (AF) in a canine model with electrical remodeling. An experimental substrate for AF was created in dogs via left atrial (LA) tachypacing (400 bpm, 3-5 weeks). NTC-801, dofetilide, and flecainide were intravenously infused for 15 minutes, and the effects on AF inducibility, atrial effective refractory period (ERP), and atrial conduction velocity were examined. The effect of NTC-801 on AF termination was also evaluated. Atrial ERP was shortened and AF inducibility was increased after LA tachypacing. NTC-801 (0.3-3 µg·kg⁻¹·min⁻¹) prolonged atrial ERP irrespective of stimulation frequency and dose-dependently decreased AF inducibility. Dofetilide (5.3 µg·kg⁻¹·min⁻¹) and flecainide (0.13 mg·kg⁻¹·min⁻¹) did not significantly inhibit AF inducibility and minimally affected atrial ERP. Flecainide decreased atrial conduction velocity, whereas NTC-801 and dofetilide did not. NTC-801 (0.1 mg/kg) converted AF to normal sinus rhythm. In summary, NTC-801 exerted more effective antiarrhythmic effects than dofetilide and flecainide in a canine LA-tachypacing AF model. The antiarrhythmic activity of NTC-801 was probably due to prolonging atrial ERP independently of stimulation frequency. These results suggest that NTC-801 could prevent AF more effectively in the setting of atrial electrical remodeling.

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