摘要
采用细胞内微电极和双微电极电压箝制术，观察缺血对绵羊心室浦肯野纤维跨膜电位和起搏离子流（Ｉｆ）的影响。结果：模拟缺血溶液灌流３０ｍｉｎ，浦肯野纤维最大舒张电位（ＭＤＰ）、动作电位幅度（ＡＰＡ）明显减小；动作电位时程ＡＰＤ５０，ＡＰＤ９０明显缩短（Ｐ＜０．０１）；Ｉｆ幅度降低，激活曲线向超极化方向移位，最大激活时间及半最大激活时间延长（Ｐ＜０．０１）。上述结果表明：心肌缺血时，心室浦肯野细胞跨膜电位及正常起搏活动不是增强，而是减弱。提示缺血性室性心律失常不是由于正常心室自律活动异常增强引起。
We employed doublemicroelectrode voltage clamp technique to detect the effect of ischemiamimic solution on the transmembrane potential and the pacemaker current(If) in sheep cardiac Purkinje′s fibers. The sequence was as follows: After being perfused with ischemiamimic solution,the maxinum diastolic potential (MDP) and the action potential amplitude(APA) were decreased, the action potential duration (APD) was shortened significantly(n=15,P<0.01), the amplitude of If was decreased,the activation curve of If was shifted to hyperpolarization, the activation time and half activation time toasteady state value of If current were prolonged (n=13,P<0.001). The above results indicated that under the ischemic condition,the transmembrane potential and the pacemaker function of cardiac Purkinje′s cell are inhibited,and acute ischemic ventricular arrhythmia may not be caused by abnormal strengthening of normal ventricular pacemaker activity.
关键词
心肌缺血
浦肯野纤维
跨膜电位
起搏离子流
cardiac ischemia Purkinje′s fibre transmembrane potential pacemaker current
