中文摘要：

目的 观察快速心房起搏对家兔心房L型钙通道基因和蛋白表达的影响及L型钙通道阻滞剂维拉帕米的保护作用.方法 新西兰大耳白家兔30只,随机分成快速起搏组和维拉帕米干预组,经右颈外静脉穿刺于右房置入电极,起搏组根据起搏时间分为P6（6h）、P12（12h）、P24（24h）、P48（48h）组和假手术组（SH组）.维拉帕米干预组在快速起搏前缓慢静脉推注维拉帕米0.2mg/kg.停止起搏后取右房组织,应用半定量反转录聚合酶链反应测定各时相点L型钙通道α1c亚单位mRNA的表达水平,Western blot检测蛋白的表达水平.结果 L型钙通道α1c亚单位表达水平在快速起搏6h后下调,并随起搏时间的延长进一步下调,mRNA和蛋白的改变一致;维拉帕米干预后,其表达水平在快速起搏6h和12h时没有改变,在起搏24h时开始下调,但幅度明显小于快速起搏组.结论 快速心房起搏可使L型钙通道亚单位mRNA和蛋白表达水平下调.维拉帕米对快速心房起搏导致的L型钙通道亚单位表达下调有保护作用.

英文摘要：

Obiective To investigate the influence of rapid atrial pacing （RAP） on the expression of α1c subunit of L-type calcium channel, and the protective effect of verapamil. Methods 30 rabbits were randomly assigned into RAP group and verapamil pre-conditioned group. Each group was further divided into 5 subgroups （n= 3 for each subgroup）. Electrode was embedded in the right atrium through right external jugular vein. Pacing was performed for 6h, 12h, 24h and 48h in different subgroups. No pacing in the sham operation group. For verapamil pre-conditioned group, the drug was intravenously administered （0.2mg/kg） 30 minutes before the initiation of rapid atrial pacing. Right atrium tissue was harvested for determination of mRNA and protein expression of L-type calcium channel subunits by reverse transcription polymerase chain reaction （RT-PCR） and Western blot. Results The mRNA level of α1c subunit started to be reduced 6h after rapid atrial pacing （RAP） and continued to decline as pacing continued, and the expression of protein was parallel with mRNA. Otherwise, the mRNA level of α1c subunit started to decrease 24h after RAP and continued to decline while pacing continued, and the expression of protein paralleled with that of mRNA in verapamil pre-conditioned group. Verapamil can attenuate the down-regulation of L-type calcium channel of the atrium induced by RAP only at 24h after RAP, but the effect was less intent. Conclusion mRNA and protein expression level of L-type calcium channel subunits decreased after RAP, The calcium channel blocker verapamil can attenuate the down-regulation of L-type calcium channel of atrium induced by RAP resulting in a decrease or postponement of calcium overload in atrial myocytes, thus exerting protective effects on atrial electrical remodeling, but such effects vanished after prolonged pacing.