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本实验旨在观察活性氧(reactive oxygen species,ROS)对人心房肌细胞电生理活动特性的影响。取有心房颤动(atrial fibrillation,AF)和非AF心脏手术患者(各12例)右心耳组织,用酶消化法得到单个心房肌细胞。两组细胞(每组n=75)分别随机分为三个亚组:对照组(n=12)、H2O2组(0.1、0.2、0.5、0.75、1、2、5、10μmol/LH2O2,每个浓度n=7)和维生素C(ROS清除剂)组(1μmol/L维生素C,n=7)。实验采用全细胞膜片钳方法记录电生理活动。与非AF对照组相比,AF对照组超快速延迟整流钾电流(ultrarapid delayed rectifier K+current,IKur)和L-型钙电流(L-type calcium current,ICa,L)电流密度(pA/pF)均明显降低(6.27±0.67vs3.77±0.56,P<0.05;6.31±0.60vs3.34±0.32,P<0.05),动作电位时程(action potential duration,APD)(ms)也明显缩短(405±13vs354±12,P<0.05)。在非AF和AF组中,H2O2对心房肌细胞IKur和ICa,L的电流密度均有浓度依赖性双向影响——高抑低促。非AF组中,H2O2浓度为0.2μmol/L时有最大增强作用,而0.75μmol/L为分界浓度,大于0.75μmol/L时,随H2O2浓度增加IKur和ICa,L的电流密度逐渐降低;在另一方面,0.2、1、2、5和10μmol/LH2O2孵育的心房肌细胞APD90与同组对照组相比均明显缩短(P<0.05),而与AF对照组相比无明显差异。在AF组中,H2O2的最大效应浓度为0.5μmol/L,而1μmol/L为分界浓度。维生素C可以逆转H2O2的上述作用,但单独给予维生素C并不改变通道特性。H2O2诱导正常人心房肌细胞发生电生理活动特性改变与AF时心肌电重构(atrial electrical remodeling,AER)相似,显示ROS可能诱发AF;同时,H2O2又能加重AF时AER,对AF有维持作用。以上结果提示ROS清除剂可能对预防和治疗AF有重要意义。
This experiment aimed to observe the effects of reactive oxygen species (ROS) on the electrophysiological activities of human atrial myocytes. Right atrial appendage was obtained from patients with atrial fibrillation (AF) and non-AF cardiac surgery (12 cases each), and single atrial myocytes were obtained by enzyme digestion. The two groups of cells (n = 75 each) were randomly divided into three subgroups: control group (n = 12), H2O2 group (0.1,0.2,0.5,0.75,1,2,5,10μmol / LH2O2, Concentration n = 7) and vitamin C (ROS scavenger) group (1 μmol / L vitamin C, n = 7). Whole-cell patch-clamp method was used to record the electrophysiological activity. Compared with non-AF control group, the AF control group had ultrarapid delayed rectifier K + current (IKur) and L-type calcium current (ICa, L) current density (pA / pF ) Were significantly lower (6.27 ± 0.67 vs 3.77 ± 0.56, P <0.05; 6.31 ± 0.60 vs 3.34 ± 0.32, P <0.05) and the action potential duration (APD) 405 ± 13 vs. 354 ± 12, P <0.05). In non-AF and AF groups, the current density of atrial myocytes IKur and ICa, L of H2O2 in a concentration-dependent two-way effect - high depression. In non-AF group, the maximum concentration of H2O2 was 0.2μmol / L, while the concentration of 0.75μmol / L was the demarcation concentration. When the concentration was greater than 0.75μmol / L, the current density of L decreased gradually with the increase of H2O2 concentration; On the other hand, APD90 of atrial myocytes incubated with 0.2, 1, 2, 5 and 10μmol / LH 2 O 2 were significantly reduced compared with the control group (P <0.05), but no significant difference compared with the AF control group. In AF group, the maximum concentration of H2O2 was 0.5μmol / L, while 1μmol / L was the demarcation concentration. Vitamin C can reverse the above effects of H2O2, but vitamin C alone does not change the channel characteristics. Similar to atrial electrical remodeling (AER), H2O2 induces changes of electrophysiological activity in normal human atrial myocytes. It suggests that ROS may induce AF. At the same time, H2O2 can aggravate AER in AF and maintain its effect on AF . These results suggest that ROS scavenger may be of great importance in the prevention and treatment of AF.