目的 研究Ryanodine受体Ser2815位点磷酸化状态的改变在心肌肥厚兔触发性室性心律失常中的作用.方法 将30只日本长耳兔随机分为3组:假手术组(Sham组)、心肌肥厚组(LVH组)、心肌肥厚+KN-93组(KN-93组),LVH组和KN-93组均通过缩窄腹主动脉建立兔心肌肥厚模型,Sham组仅游离腹主动脉不进行缩窄.8周后行超声心动图证实心肌肥厚形成,制备兔左室楔形心肌块的灌流模型,同步记录心内、外膜动作电位及跨壁心电图.KN-93组预先给予KN-93预灌,然后观察各组在异丙肾上腺素(1 μmol/L)灌流和快频率程序刺激下触发活动和室性心动过速的发生率.灌流完毕后取左室心肌组织,应用Western blot检测各组心肌Ryanodine受体总量及其Ser2815位点磷酸化蛋白水平.结果 Sham组、LVH组和KN-93组触发活动的发生率分别为0/10、10/10、4/10,室性心动过速或室颤的发生率分别为0/10、9/10、3/10,KN-93组均较LVH组明显降低(均P＜0.05);LVH组Ryanodine受体总量及Ser2815位点磷酸化蛋白水平较Sham组增加(均P＜0.05),KN-93组Ser2815位点磷酸化蛋白水平较LVH组减少(P＜0.05).结论 KN-93可通过降低Ryanodine受体Ser2815位点的磷酸化水平抑制肥厚心肌的室性心律失常,Ryanodine受体的过度磷酸化是触发性心律失常发生的重要机制之一.%Objective To investigate the role of the phosphorylation of ryanodine receptor at Ser2815 in left ventricular hypertrophy (LVH) and triggered ventricular arrhythmia in rabbits. Methods Japanese rabbits were randomly divided into three groups (n=10 in each) : sham group, LVH group and KN-93 group. The LVH models were established by coarctation of the abdominal aorta in rabbits in the LVH and KN-93 groups. Animals in the sham group had the abdominal aorta exposed but not narrowed. After 8 weeks,action potentials (APs) were recorded simultaneously in the endocardium and epicardium,and a trans-mural electrocardiogram was obtained in the left ventricular wedge preparations. The rabbits in KN-93 group were pre-perfused with KN-93,and then the frequency of triggered APs and ventricular tachycardia was recorded under perfusion of isoprenaline (1 μimol/L) and high-frequency stimulation in each group. And the total ryanodine receptor protein and phosphorylated level at Ser2815 were detected by using Western blot. Results The frequency (animals/group) of triggered APs was 0/10,10/10 and 4/10, and the frequencies of ventricular tachycardia or fibrillation were 0/10,9/10 and 3/10 in the sham group, model group and KN-93 group,respectively. The frequencies in the KN-93 group were much lower than those in the LVH group (P<0. 05). The total ryanodine receptor protein and phosphorylated level at Ser2815 were much higher in the LVH group than those in the sham group (P<0. 05) , while they were much lower in the KN-93 group than in the LVH group (P<0. 05). Conclusion KN-93 can effectively reduce the occurrence of triggered ventricular arrhythmia by down-regulating the phosphorylated level of ryanodine receptor at Ser2815 in rabbits with LVH. Hyperphosphorylation of ryanodine receptor plays an important role in the development of triggered ventricular arrhythmia.
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