短暂外向钾电流参与T波电交替的实验研究  

Role of transient outward potassium current in T wave alternation

作　　者：王晞[1] 顾永伟[1] 唐艳红[1] 陈葵[1] 

机构地区：[1]武汉大学人民医院心内科,湖北武汉430060

出　　处：《心血管康复医学杂志》2008年第4期402-405,共4页Chinese Journal of Cardiovascular Rehabilitation Medicine

摘　　要：目的:观察短暂外向钾电流(Ito)是否参与T波交替(T wave alternans,TWA)现象的发生或维持。方法:成熟雄性SD大鼠离体灌流心脏,分为对照组和4-氨基吡啶(AP)灌流组(2mM 4-AP持续灌流),在右室外膜给予200ms的方波刺激,并逐渐缩短刺激周长至不应期或出现TWA,同步记录灌流心脏的心电图及三层心肌的动作电位,观察TWA的发生情况。结果:大鼠离体灌流心脏心电图QRS与T波之间没有明显的等电位线,心外膜最早完成复极,复极终点与心电图T波顶点一致,中层及心内膜较晚完成复极,复极终点与心电图T波终点一致。快频率刺激未诱发对照组TWA,4-AP组在刺激周长为92±6ms时可诱发TWA,刺激周长缩短至78±8ms时引起持续TWA。结论:Ito是动作电位复极1期的主要外向电流,Ito阻断可通过影响动作电位复极,细胞内钙稳态,引起T波电交替。Objective： To investigate the role of transient outward potassium （Ito） in T wave alternation. Methods, In 24 isolated rat hearts, ECG signals and monophasic action potentials （MAPs） from epicardium, mid-myocardium and endocardium were simultaneously recorded. The heart was paced at basic cycle length （BCL） of 200 ms, and the effects of 4-aminopyridine （4--AP）, a blocker of Ito, at rapid pacing were investigated. Results： Neither T wave alternation nor alternation of MAP duration could be induced in the control group which is absence of 4- AP. In the presence of 4-AP （2 mmol/L ）, at the cycle length of （92±6） ms （CL） prominent T wave alternation was produced. Marked beat-to-beat alternations of the T-wave were observed at the cycle length of （78±8） ms. Conclusion： The results suggest that Ito also plays a role in T wave alternation in heart at rapid pacing, which is associated with ventricular arrhythmia following acceleration of heart rate.

关 键 词：钾通道 心电描记术 动物 实验 

分 类 号：R540.410.9[医药卫生—心血管疾病]