Atrial-selective block of sodium channels by acehytisine in rabbit myocardium

• Main Authors: Xinrong Fan (Author), Chao Wang (Author), Na Wang (Author), Xianhong Ou (Author), Hanxiong Liu (Author), Yan Yang (Author), Xitong Dang (Author), Xiaorong Zeng (Author), Lin Cai (Author)
• Format: Book
• Published: Elsevier, 2016-12-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1347-8613; 10.1016/j.jphs.2016.03.014
• Keywords: Acehytisine; Sodium channel; Atrial-selective; Atrial fibrillation; Patch-clamp; Therapeutics. Pharmacology; RM1-950
• Source: Journal of Pharmacological Sciences, Vol 132, Iss 4, Pp 235-243 (2016)

Acehytisine, a multi-ion channel blocker, can markedly inhibit INa, ICa, IKur, If at various concentrations and effectively terminate and prevent atrial fibrillation (AF) in patients and animal models, but the molecular mechanism underlying its blockage remains elusive. In this study, we investigated the effects of acehytisine on action potentials and sodium channels of atrial and ventricular myocytes isolated from rabbit, using whole-cell recording system. We found that acehytisine exerted stronger blocking effects on sodium channels in atria than in ventricles, especially at depolarization (IC50: 48.48 ± 7.75 μmol/L in atria vs. 560.17 ± 63.98 μmol/L in ventricles). It also significantly shifted steady state inactivation curves toward negative potentials in atrial myocytes, without affecting the recovery kinetics from inactivation of sodium channels in the same cells. In addition, acehytisine inhibited INa in a use-dependent manner and regulated slow inactivation kinetics by different gating configurations. These findings indicate that acehytisine selectively blocks atrial sodium channels and possesses affinity to sodium channel in certain states, which provides additional evidence for the anti-AF of acehytisine.