Hyperpolarization activated cation current (If) in cardiac myocytes from pulmonary vein sleeves in the canine with atrial fibrillation
Hyperpolarization activated cation current (If) in cardiac myocytes from pulmonary vein sleeves in the canine with atrial fibrillation作者机构：Institute of Geriatric Cardiology Chinese PLA General Hospital 28 Fuxing Road Beijing 100853 China
出 版 物：《Journal of Geriatric Cardiology》 (老年心脏病学杂志（英文版）)
年 卷 期：2012年第9卷第4期
页 面：366��-374页
核心收录：
基 金：国家自然科学基金
主 题：Atrial fibrillation Canine Cardiac myocytes Cation current β-receptor
摘 要：Objective To investigate the characteristics of ectopic automaticity and cation current (If) of cardiac myocytes from pulmonary vein sleeves (PVs) in canines with atrial fibrillation. Methods The canines (8–10 years old) were subjected to long-term, rapid atrial pacing (RAP) for 10 weeks, which induced the atrial fibrillation model. Disassociation of PVs of canines yielded single cardiac myocytes from a Landengorff column. Action potential, If and hyperpolarisation activated cyclic nucleotide-gated (HCN) currents were measured with the patch-clamp technique. Results Compared with the control group, cardiac myocytes from the RAP canine PVs had spontaneous diastolic depolarization, shorter action potential duration, and larger If densities. In the group of RAP cells, the half maximal activation potential (V1/2) was found to be less negative (��105.5 ±5.2 mV) compared to control cells (��87.3 ±4.9 mV). Current densities of If were increased significantly by β-adrenergic receptor stimulation with isoproterenol and caused an acceleration of current activation. In contrast, If currents in the RAP were reduced by carvedilol, a selective beta-adrenergic receptor. Another important finding is that HCN4-based channels may make a significant contribution to If in PVs cells, but not HCN2. Meanwhile, HCN4 current significantly increases in canine PVs cardiac myocytes with RAP. Conclusions The spontaneous action potential and larger If currentwere observed in the PVs cardiac myocytes using RAP, whichmay contribute tomore ectopic activity events to trigger and maintain atrial fibrillation.
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