钙离子通道基因mRNA表达在心房颤动发生机制中的作用

Calcium channel gene mRNA expression effects in atrial fibrillation mechanisms

目的:探讨钙离子通道基因mRNA表达在心房颤动(房颤)发生机制中的作用。方法:杂种犬15只,随机分为3组,分别为正常对照组、单纯房颤组和房颤加mibefradil组。房颤组置入埋藏式高频率心脏起搏器,起搏频率520次/min。正常对照组不置入起搏器。术后观测24周。采用RT-PCR扩增心房肌组织的L型钙通道α1亚单位、T型钙通道α1H亚单位、钠/钙交换体和Kv4.3基因的mRNA。结果:单纯房颤组与正常对照组相比较,L型钙钙通道α1亚单位的mRNA有轻微下调(P>0.05),T型钙通道α1H亚单位的mRNA明显上调(P<0.05),钠/钙交换体的mRNA下调13%(P>0.05),Kv4.3基因的mRNA明显下调(P<0.05)。房颤加mibefradil组与单纯房颤组相比较,钠/钙交换体的mRNA上调10%(P>0.05),Kv4.3基因的mRNA上调(P<0.05)。结论:持续性房颤6个月时T型钙通道α1H亚单位mRNA的表达显著增加而Kv4.3mRNA的表达显著下调,可能是持续性房颤钙超载的主要原因。而L型钙通道α1亚单位和钠/钙交换体mRNA的表达无明显改变,提示它们可能在房颤的发生机制中不起重要作用。

Objective：To investigate calcium channel gene mRNA expression effects in atrial fibrillation mecha nisms. Method：Fifteen dogs were randomly individed into three groups-atrial fibrillation group （n= 5）, atrial fibrillation and mibefradil group （n=5） and control group （without pacemaker implantation） （n=5）. Atrial fibril lation dogs underwent continuous rapid atrial pacing （520 bpm） for twenty-four weeks to create persistent atrial fibrillation. L-type calcium channel α1 subunit, T-type calcium channel α1H subunit, Na＋/Ca2＋ exchanger and Kv4.3 mRNA were analysed by reverse transcription and polymerase chain reaction （RT PCR）. Result：In the atrial fibrillation group, Ltype calcium channel α1 subunit mRNA slightly decreased （P〉0.05）, T-type calcium channel α1H subunit mRNA remarkably increased （P〈0.05）, Na＋/Ca2＋ exchanger mRNA did not change signifi cantly （P〉0.05）, and Kv4.3 mRNA significantly decreased （P〈0.05）, compared with in the control group. Conelusion：T type calcium channel α1H subunit mRNA significantly increased and Kv4.3 mRNA significantly de creased, which may be a major cause of calcium overload in persistent atrial fibrillation for six months. L-type calcium channel α1 subunit and Na＋/Ca2＋ exchanger mRNA did not change remarkably, suggesting that they did not play an important role in atrial fibrillation mechanisms.