钙调蛋白激酶Ⅱ抑制剂抗肥厚心肌室性心律失常发生机制的研究

The Roles of Calmodulin Kinase Ⅱ Inhibitor in Ventricular Arrhythmias in Rabbits with Cardiac Hypertrophy

目的探讨钙调蛋白激酶Ⅱ特异性抑制剂KN-93抗肥厚心肌室性心律失常发生的机制。方法雌性新西兰大白兔随机分为4组：假手术组（sham组）、心肌肥厚组（LVH组）、心肌肥厚＋KN-93组（KN-93组）、心肌肥厚＋KN-92组（KN-92组），每组14只。LVH组、KN-93组及KN-92组通过缩窄腹主动脉制备兔心肌肥厚模型。8周后，制备兔左室楔形心肌块的灌注模型，同步记录心内、外膜动作电位及跨壁心电图，观察低钾（2mmol／L）、低镁（0．25mmol／L）蒂罗德液灌流及慢频率（2000～4000ms）刺激条件下各组早期后除极（EAD）和尖端扭转型室性心动过速（Tdp）的发生率。采用胶原酶消化法分离单个心肌细胞，应用膜片钳技术记录动作电位（AP），观察低钾、低镁蒂罗德液灌流及慢频率（0.25～0.5Hz）刺激条件下，各组EAD的发生率。结果在低钾、低镁蒂罗德液灌流及慢频率刺激条件下，兔左室楔形心肌块水平，sham组、LVH组、KN-92组（0.5μmol／L）及KN-93组（0．5μmol／L）EAD的发生率分别为0／10、10／10、9／10和5／10，Tdp的发生率分别为0／10、5／10、4／10和1／10。单个心肌细胞水平，Sham组、LVH组、KN-92组（0．5μmol／L）及KN-93组（0.5μmol／L）EAD的发生率分别为0／12、11／12、10／12和5／12。结论钙调蛋白激酶Ⅱ介导心肌肥厚兔室性心律失常的发生，其主要作用机制是通过增加EAD的发生率，从而触发室性心律失常的发生。

Objective To investigate the role of calmodulin kinase Ⅱ on ventricular arrhythmias in rabbits with cardiac hypertrophy by use KN-93, a kind of ealmodulin kinase Ⅱ inhibitor. Methods Fifty-six female New Zealand white rabbits were randomly divided into 4 groups：sham group, LVH group, KN-92 group and KN-93 group. In LVH group, KN-92 group and KN-93 group, the abdominal aorta was partially constricted. Eight weeks later：①The arterially perfused left ventricular wedge preparations were made, transmembrane action potentials （TAP） from epicardium and endocardium were simultaneously recorded together with a transmural ECG. The incidence of EAD and Tdp with slow stimulation （2 000-4 000 ms） and hypokalemie （2 mmol/L）, hypomagnesaemie （0. 25 mmol/L） Tyrode＇ s solution in left ventrieular wedge preparations was observed.② Myocytes were isolated by enzymatic method, and whole cell patch clamp technique was used to record the action potential. The incidence of EAD with slow stimulation （0.25-0.5 Hz） and hypokalemie （2.0 retool/L）, hypomagnesaemie （0.25 retool/L） Tyrode＇s solution in single ventricular cells was observed. Results ①With slow stimulation and hypokalemic, hypomagnesaemic Tyrode＇s solution in left ventricular wedge preparations, the incidence of EAD in sham group, LVH group, KN-92 group （0.5 μmol/L） and KN-93 group （0.5 μmol/L） was 0/10, 10/10, 9/10 and 5/10 respeetively;The incidence of Tdp in sham group, LVH group, KN-92 group （0.5 μmol/L） and KN-93 group （0.5 μmol/L） was 0/10, 5/10, 4/10 and 1/10 respectively;②With slow stimulation and hypokalemic, hypomagnesaemic Tyrode＇s solution in single ventricular cells, the incidence of EAD in sham group, LVH group, KN-92 group （0, 5μmol/L） and KN-93 group （0, 5 μmol/L） was 0/12, 11/12, 10/12 and 5/12 respectively. Conclusion Calmodulin kinase Ⅱ mediates the occurrence of ventricular arrhythmias in rabbits with cardiac hypertrophy by increasing the incidence of EAD.