慢性心房颤动患者心房肌KChIP2基因mRNA水平的定量检测

Atrial myocytes KChIP2 mRNA expression in rheumatic heart disease patients with atrial fibrillation

目的心房颤动（房颤）是最为常见的快速性心律失常之一。钾通道相关蛋白2（K^＋ channel interacting protein 2，KChIP2）是心肌细胞瞬时外向钾通道的重要辅助亚单位，在Ito发挥正常功能中起着重要的作用。报告采用实时荧光定量聚合酶链反应（PCR）技术通过对房颤时KChIP2和Kv4．3基因mRNA水平进行定量研究，探讨KChIP2在房颤中的作用和对于瞬时外向钾通道的可能调控机制。方法（1）30例风湿性心脏病患者分为两组：窦性心律组（窦律组）13例，持续性房颤组（房颤组）17例，取其常规切除的右心耳组织作为研究对象；（2）提取心房肌组织总RNA，通过RT-PCR和TA克隆技术构建含有目的基因片段的质粒标准品；（3）以GAPDH为内参照基因，采用SYBR Green Ⅰ法实时荧光定量PCR技术检测持续性房颤和窦律患者KChIP2和Kv4．3基因mRNA水平。结果（1）标准曲线和熔解曲线：标准曲线线性关系良好，相关系数R^2〉0．99。熔解曲线呈明显单峰状，退火温度与预测值基本一致；（2）窦律组和房颤组KChIP2／GAPDH比值分别为0．2200±0．0388、0．1468±0．0452，房颤组KChIP2基因mRNA水平低于窦律组，P〈0．01；窦律组和房颤组Kv4．3／GAPDH比值分别为0．5257±0．1427、0．3946±0．1826，房颤组Kv4．3基因mRNA水平低于窦律组，P〈0．05。结论与窦律患者相比，房颤患者KChIP2基因和Kv4．3基因明显下调，KChIP2和Kv4．3基因下调是房颤时Ito电流下调的分子基础。

Objective To detect the KChIP2 mRNA level in rheumatic heart disease patients with or without atrial fibrillation （AF） by real-time PCR. Methods Right atrial appendage samples from rheumatic heart disease patients with （ n = 17 ） or without AF （ n = 13 ） were obtained during cardiac surgery. Total RNA was extracted from the atrial tissues, and the KChIP2 and Kv4. 3 mRNA were detected by SYBR Green Ⅰ real-time PCR with the GAPDH as the house keeping gene. Result The ratio of KChIP2/ GAPDH （0. 1468 ±0. 0452 vs. 0. 2200 ±0. 0388, P 〈0. 01 ） and the ratio of Kv4. 3/GAPDH （0. 3946 ± 0. 1826 vs. 0. 5257 ± 0. 1427, P 〈 0. 05 ） were significantly lower in AF patients compared to non-AF patients. Conclusion Down-regulated atrial KChlP2 and Kv4. 3 mRNA expressions in rheumatic heart disease patients with chronic AF might be one of the molecular bases responsible for the down-regulation of the Ito current density of AF.