摘要
目的 研究风湿性心脏病 (RHD)慢性心房颤动 (房颤 )使心房肌细胞膜超快速激活钾电流 (IKur)的变化 ,探讨离子通道改变在房颤时心房电重构 (AER)中的作用。方法 采集 2 3例RHD患者(房颤组 12例 ,窦性心律组 11例 )心房肌标本 ,采用急性酶解法 ,将组织块分解以获得游离的心房肌细胞 ;应用膜片钳全细胞技术 ,记录两组患者心房肌细胞膜IKur电流 ,并对比分析两组的电流 电压曲线以及稳态激活和失活的动力学特性。结果 在钳制电位 + 10mV～ + 50mV时 ,房颤组IKur密度明显低于窦性心律组 (P <0 0 5) ;其中 ,除极化至 + 50mV时 ,密度分别为 (4 92± 1 48)pA/pF(n =19个细胞 )和 (9 3 1± 1 44) pA /pF(n =2 1个细胞 ,P <0 0 1)。房颤组右心房细胞IKur的激活最大电导较窦性心律组明显降低 ,分别为 (2 75± 0 55)nS(n =2 1个细胞 )和 (4 74± 0 63 )nS(n =2 1个细胞 ,P <0 0 1)。房颤组在 + 50mV时的失活率为 56% ,低于窦性心律组 (P <0 0 5) ,而两组的稳态激活和失活特征的差异无显著性。结论 现有数据显示 ,IKur密度的改变可能是慢性房颤时AER中多种离子通道重构的重要机制之一 ,可能与房颤时心肌细胞的传导性、不应期等改变有关 。
Objective To study the effects of ch ro nic atrial fibrillation(AF)on the ultra-rapid delayed rectifier current (I Kur ) in patients with rheumatic heart disease (RHD) and to evaluate the p ossible roles of the current changes in the atrial electrical remodeling (AER) caused by AF.Methods Specimens of human atrial appendage were obtained from 23 RHD patients (12 with chronic AF and 11 with normal sinus rhy thm).Single atrial myocytes were acutely dissociated by tissue chunk enzymatic digestion and the whole-cell patch-clamp techniques were used to study current -voltage relations and gating kinetics of I Kur in the two groups. ResultsI Kur amplitudes were significantly reduced and the c urrent density of I Kur in AF patients were lower than that in SR patients (command potential between +10 mV and +50 mV).The I Kur densities (9.31 ±1.44)pA/pF( n =21 cells) at command potential of +50 mV was significantly lower than that in SR patients (4.92±1.48)pA/pF,( n =19 cells, P< 0.01 ).Both the maximum activation conductance and inactivation percentage in AF gro up were lower than those in SR group.No remarkable differences in parameters for activation and inactivation properties were noted in both the two groups.Conclusions The reduction of I Kur may be one of the major mecha nisms of AER associated with several kinds of cardiac ionic channels in AF patie nts and is therefore related to changes in atrial conduction and refractory peri od.The specific relations between changes of I Kur and AF initiation and pe rpetuation and its therapeutic significance are to be further elucidated.
出处
《中华心律失常学杂志》
2003年第5期295-298,共4页
Chinese Journal of Cardiac Arrhythmias
