房颤患者心房肌瞬间外向钾电流表达的变化

Alterations in Transient Outward Current mRNA Expression in Atria of Patients with Persistent Atrial Fibrillation

目的:心房有效不应期缩短是使房颧持续的重要原因之一。Ito电流是复极化早期重要的外向电流。此电流活动增加,可使心房动作电位时程及有效不应期缩短。本研究观察房颤患者Ito电流mRNA表达的变化,从分子水平探讨房颤发生的机制。方法:26例行开胸心脏手术的患者,取右心耳50mg。分为两组:窦性心律组15例;持续房颤组11例。采用逆转录聚合酶链反应的方法测定两组患者瞬间外向钾电流mRNA表达的变化。结果:持续房颤患者左心房内径明显较窦性心律患者大[(51.18±9.1 2)mm比(34.27±4.06)mm,P<0.01]。房颤患者Itol(Kv4.3α)基因表达明显减少[(0.91±0.20)比(0.33±0.07),P<0.01]。结论:Kv4.3α基因表达下调可延长心房肌的动作电位时程及有效不应期,房颤患者此基因表达的下调可能是其对抗房颤引起的动作电位时程缩短的一种自适应现象。

Objective: Shortening of effective refractory period (ERP) of atria is a main mechanism for AF to be persistent. Transient outward current (Ito) is an important ion current responsible for early repolarization of atria. Increased activities of this channel can shorten ERP. We planned to measure Ito 1(Kv4.3α) to study on the mechanism of AF. Methods: Right atrial appendages were abtained from 26 patients undergoing open heart surgery. Among them 11 had persistent AF and 15 were matched controls in sinus rhythm. Transient outward channel were measured by semiquantitative polymerase chain reaction.Results: Clinical parameters were matched between 2 groups except that left atrial diameter were larger in patients with AF than in patients with sinus rhythm [(51.18±9.12)mm vs (34.27±4.06) mm, P<0.01] . mRNA levels of Kv4.3α were significantly reduced in AF patients compared with patients with sinus rhythm from [(0.91±0.20) to (0.33±0.07), P<0.01].Conclusion: Downregulation of mRNA of Kv4.3α can lengthen action potential duration and effective refractory period of atria. Persistent AF is accompanied by reduction in mRNA of Kv4.3α, which may be an adaptation mechanism that serves to prolong the initially reduced atrial effective refractory period.