缺血再灌注致心律失常大鼠模型钙调蛋白介导的L型离子通道电流的变化

目的：探讨缺血再灌注致心律失常大鼠钙调蛋白（CaM）的变化及其对L型离子通道电流的影响。方法：选取健康SD大鼠48只，以单盲法随机分为4组（n=12）；空白组不做任何处理，模型组以左冠状动脉前降支结扎法制备缺血再灌注致心律失常模型，干预组在制备缺血再灌注致心律失常模型前肌注钙调蛋白抑制剂W-7（100μmol／kg），假手术组仅进行开胸手术和动脉套线，无结扎。模型制备成功后，取大鼠心脏组织，以免疫印迹法检测L型钙离子通道主要亚型CaV1．2功能决定性亚单位α1C和CaM的表达水平；同时分离大鼠心肌细胞，以膜片钳技术进行L型离子通道电流（ICa，L）测定。结果：模型组大鼠心肌组织的a1C、CaM的表达水平，以及ICa，L均高于空白组和假手术组，差异具有统计学意义（P〈0．05）；较模型组相比，干预组CaM的表达水平和ICa，L均有降低，差异具有统计学意义（P〈0．05）；I—V曲线有所上移，a1C的表达水平比较，差异无统计学意义（P〉0．05）。结论：ICa，L过激所致Ca抖内流和细胞超载为缺血再灌注后心肌损伤和心律失常的重要因素之一，CaM在该病理过程中能够发挥不依赖于L型离子通道表达水平的调节作用，可作为其临床治疗的新靶点。

Changes of L-type calcium channel currents mediated by calmodulin in ischemia- reperfusion induced arrhythmia rat model

T Objective： To discuss the expression changes of calmodulin as well as its effects on L- type calcium channel currents in arrhythmia rat models induced by ischemia-reperfusion. Methods. A total of 48 healthy SD rats were selected and randomly divided into 4 groups （n= 12） with single blind method. The control group was fed normally, and the model group was prepared for ischemia-reperfusion induced arrhythmia models with left anterior descending coronary artery ligation, and the intervention group was injected with calmodulin inhibitors W-7 （100 μmol/kg） before the preparation of ischemia-reperfusion in- duced arrhythmia models, while the sham-operation group was only given open chest surgery without liga- tion. Then the rat heart tissues of each group were extracted to detect L-type calcium channelalC and ealmodulin expression; besides, the myocardial cells were separated to detect the L-type calcium channel currents by patch-clamp technique. Results： Compared with the control and sham-operation group, the model group had higher expression level of calmodulin, and L-type calcium channel alC, as well as a high- er L-type calcium channel currents （P〈0.05）. However, compared with the model group, the interven- tion group had a lower expression level of calmodulin as well as a lower L-type calcium channel currents （P d0.05） ; while the L-type calcium alC expression level had no significant difference between each group （P〈0.05）. Conclusion. Ca2＋ influx and overload caused by the aggressive of L-type calcium channel cur- rents which contributes to myocardial injury after ischemia reperfusion is one of important factors for is- chemia-reperfusion induced arrhythmias. Furthermore, calmodulin could play an important role independ- ent of L-type calcium channel and could set light on novel targets for clinical treatment.