地昔帕明预处理对心肌缺血后心室肌单向动作电位和有效不应期的影响

Effect of Desipramine Pretreatment on Monophasic Action Potentialand and Effective Refractory Period in Ventricular Myocardium after Myocardial Ischemia

目的探讨地昔帕明预处理对大鼠心肌缺血后心室肌单向动作电位和有效不应期的影响。方法SD大鼠随机分为3组:心肌缺血组夹闭左冠状动脉前降支30 min;地昔帕明组(预处理组)先单次静脉给予地昔帕明0.8mg/kg,5 min后夹闭左冠状动脉前降支30 min;假手术组仅开胸但不夹闭左冠状动脉。喂养1周后开胸测定单向动作电位(MAP)和有效不应期(ERP)。结果心肌缺血组梗死周边区心室肌的MAPD50、MAPD90和ERP较假手术组显著延长(P<0.05);地昔帕明预处理后,其MADP90和ERP比心肌缺血组明显缩短(P<0.05)。与非梗死区心室肌的MADP90和ERP相比,梗死周边区心室肌的MADP90和ERP显著延长(P<0.05),地昔帕明组的ERP离散度较心肌缺血组降低。结论心肌缺血后心室的复极化不均一性和ERP离散度增加,地昔帕明预处理能够增加缺血心肌的电稳定性,发挥抗心律失常作用。

Objective To investigate the effect of desipramine pretreatment on monophasic action potential（MAP） and effective refractory period（ERP） in ventricular myocardium of rats with induced acute myocardial ischemia. Methods SD rats were randomly assigned into three groups： In the myocardial ischemia group, the left anterior descending coronary artery （LAD） was clamped for thirty minutes. In the desipramine group, five minutes prior to clamping, desipramine （0.8 mg/kg） was administered intravenously. In the sham-operated group rats were only operated without clamping the coronary artery. One week after the operation, MAP and ERP were measured. Results MAPD50. MAPD90 and ERP in ventricular myocardium of infarcted border zone of myocardial ischemia group were significantly longer than those of sham-operated group （P〈0.05）. After desipramine pretreatment, MAPD90 and ERP were significantly shorter than those of myocardial ischemia group（P〈0.05）. Compared with MAPD90 and ERP in ventricular myocardium of non-infarcted zone, MAPD90 and ERP in ventricular myocardium of infarcted border zone prolonged significantly（P〈0.05）. The dispersion of ERP in desipramine group was lower than that in myocardial ischemia group. Conclusion Heterogeneity of repolarization and the degree of dispersion of ERP in ventricle increased after acute myocardial ischemia. Desipramine pretreatment could increase electrical stability of ischemic myocardium to take antiarrhythmic effect.