K_(ATP)通道阻断剂对兔缺血心室肌跨壁离散度的影响

Effect of KATP channel on transmural dispersion of reporlarization of ventricular myocytes after myocardial infarction

目的探讨免冠脉结扎前后缺血区心室肌单相动作电位时程(MAPD100)和跨壁离散度(TDR)的动态变化,观察阻断KATP通道后缺血区心室肌的单相动作电位(MAP)参数变化。方法30只家兔随机分为单纯缺血组(n=15)和GLB(glibenclamide)组(n=15)。单纯缺血组开胸,制作缺血模型,利用整合的3层心肌同步记录MAP电极,并结合程控刺激技术,测量结扎前、结扎后5 min、30 min、1 h、1 d、2 d的缺血区3层心肌MAPD100并计算TDR。GLB作为KATP通道阻断剂预处理实验组,制作缺血模型,相同时间点记录3层心肌MAPD100并计算TDR。结果与结扎前比较,单纯缺血组冠脉结扎后5 min^1 h 3层心肌MAPD100均缩短有统计学意义,以MAPDmid100缩短最为显著,TDR与结扎前比较增大有统计学意义。在1 d、2 d的时间点上与结扎前比较TDR变化无统计意义。GLB组结扎后5 min^1 h Mid、Epi层MAPD与单纯缺血组比较增大有统计学意义,TDR减小有统计学意义。结论使用KATP通道阻断剂GLB可减小冠脉结扎后初期心室肌TDR增大程度。

AIM To investigate the dynamic variations of monophasic action potential duration （MAPDloo ） and transmural dispersion of repolarization （TDR） in the ischemic zone after coronary artery ligated and to observe the changes of the MAP parameters following blocking the KATP channel. METHODS Thirty rabbits randomized into ischemic group （ n = 15 ） and GLB （glibenclamide） group （n = 15）. Ischemic group, anterior wall myocardial ischemic was ligated. Combined with the programmed electrical stimulation technique, we employed monophasic action potential recording technique to measure the MAPDloo of subendocardium, midmyocardium, subepicardium and TDR at baseline before ligated at first and 5 min, 30 min, 1 h and 2 d after ligation. GLB used as KATP channel blocker, was applied to the GLB group. After ligating coronary arery, we measured MAPD100 of three layers of myocardium and TDR at the same time sites as ischemic group in ischemic zone. RESULTS In ischemic group, MAPD100 of 3 layers of myocardium all shortened at the time sites of 5 min, 30 min and 1 h after ischemic, especially MAPDmid100, which reduced most. Compared with the TDR at the baseline, TDR increased and the difference was statistically significant. TDR increased and had statistical significance by 1 d and 2 d after ligation compared with the baseline. In GLB group compared with the ischemic group, MAPD100 of midmyocardium shortened 5 rain, 30 rain and 1 h after ligation, TDR decreased and difference was statistically significant. CONCLUSION GLB used as KATP channel blocker can reduce the extent of augmentation of TDR in the initial stage when coronary artery was ligated.