丹曲林对心肌缺血再灌注小鼠室性心律失常易感性的影响及其电生理机制:离体实验

Effect of dantrolene on susceptibility to ventricular arrhythmias and electrophysiological mechanism in a mouse model of myocardial ischemia-reperfusion:an in vitro experiment

目的评价丹曲林对心肌缺血再灌注小鼠室性心律失常易感性的影响及其电生理机制。方法SPF级健康雄性C57BL/6小鼠20只,6~8周龄,体重21~25 g,制备Langendorff离体心脏灌注模型。取离体灌注模型制备成功的心脏20个,采用随机数字表法分为对照组和丹曲林组,每组10个。采用停止灌流30 min后恢复灌流的方法建立全心缺血再灌注损伤模型。丹曲林组于再灌注时灌注含20μmol/L丹曲林钠的Krebs液5 min。再灌注10 min时,通过程序电刺激诱发室性心律失常,记录室性心律失常成功诱发情况和持续时间。于停灌前和再灌注20 min时测定心室有效不应期(ERP)及左心室中段外膜心肌细胞动作电位时程(APD50和APD90)。再灌注30~60 min时采用光学标测技术检测心肌细胞内钙离子浓度变化,记录钙瞬变交替发生情况及舒张期细胞内钙离子浓度自发升高(SCaE)幅度。结果与对照组比较,丹曲林组室性心律失常诱发率降低,持续时间缩短,再灌注20 min时心室ERP、APD50和APD90延长,钙瞬变交替发生率及SCaE幅度降低(P<0.05)。结论丹曲林可降低心肌缺血再灌注小鼠室性心律失常的易感性,其电生理机制可能与降低心肌细胞传导性和兴奋性、延长复极时程以及恢复胞内钙离子稳态有关。

Objective To evaluate the effect of dantrolene on susceptibility to ventricular arrhythmias and the electrophysiological mechanism in a mouse model of myocardial ischemia-reperfusion.Methods Healthy specific pathogen-free male C57BL/6 mice,aged 6-8 weeks,weighing 21-25 g,were used for establishing Langendorff-perfused isolated heart model.Twenty Langendorff-perfused isolated hearts were divided into control group and dantrolene group using the random number table method,with 10 hearts in each group.Global myocardial ischemia was induced by interrupting perfusion for 30 min followed by reperfusion.The hearts were perfused with 20μmol/L dantrolene sodium in Krebs solution for 5 min starting from the beginning of reperfusion in dantrolene group.Programmed electrical stimulation was used to induce ventricular arrhythmias at 10 min of reperfusion,and the successful induction and duration of the ventricular arrhythmia were recorded.The ventricular effective refractory period(ERP)and action potential durations(APD50 and APD90)at middle left ventricular epicardial cardiomyocytes were recorded before interrupting perfusion and at 20 min of reperfusion.The changes in concentrations of calcium in cardiomyocytes were measured by the optical mapping method at 30-60 min of reperfusion,and the occurrence of calcium transient alternans and amplitude of diastolic spontaneous calcium elevation(SCaE)were recorded.Results Compared with control group,the rate of ventricular arrhythmia reduced was significantly decreased,the duration was shortened,the ventricular ERP,APD50 and APD90 were prolonged at 20 min of reperfusion,and the incidence of calcium transient alternans and amplitude of SCaE were decreased in dantrolene group(P<0.05).Conclusion Dantrolene can decrease the susceptibility to ventricular arrhythmias in a mouse model of myocardial ischemia-reperfusion,and the electrophysiologic mechanism may be related to decreasing the conductivity and excitability of cardiomyocytes,prolonging the repolarization duration and restoring intracellular calcium homeostasis.