中文摘要：

目的探讨交界区逸搏节律的细胞及电生理学基础。方法组织切片Masson染色；酶解分离单个心肌细胞；单细胞膜片钳技术研究具有自律特性细胞的动作电位特征。结果组织学研究发现家兔致密结及房室结后延伸细胞组成具有异质性且呈规律性排列；单细胞形态学观察可见不同于普通心房肌细胞的起搏细胞（PC）、过渡细胞α（TCα）和β，且PC和TCα呈现自发规律性收缩。三种细胞相比较，在动作电位波形、最大舒张电位、0期除极速度、动作电位复极至90％时程（APD90）、舒张期自动除极速率（VDD）、动作电位超射值及幅值方面，PC和TCα之间除APD90和VDD外，其他各指标差异无统计学意义（P〉0．05）。TCβ与PC、TCα分别相比，各项指标差异均有统计学意义（P均〈0．05）。结论家兔致密结及房室结后延伸具有自律特性的PC及TCα可能是交界区逸搏节律的细胞学基础。

英文摘要：

Objective To explore the cytological and electrophysiological basis of junctional rhythm Methods Histological sections were stained by Masson method to observe the arrangement of cardiac cells in junctional area of rabbit heart; single viable cells were isolated enzymatically for morphological research; whole-cell patch clamp was employed to study the action potential properties of specialized cardiac cells. Results Histologically, the cellular components in compact AV node and PNE were heterogeneous; the cells were organized regularly. Cytologically, the specialized cells PC, TCα andβ were presented with the former two types automatically contracted. Electrophysiologically, the action potential configuration, maximum depolarization potential, action potential duration to 90% repolarization, velocity of depolarization in phase 0, velocity of phase 4 depolarization, overshoot and amplitude of action potential between PC and TCa were not significantly different except for action potential duration to 90% repolarization and velocity of phase 4 depolarization （all P〉0. 05） ; conversely, the above parameters between TCβ and PC, TCα respectively were specialized PC and TCα which demonstrated automaticity significantly different （all P〈0.05）. Conclusion The might construct the leading pacemaking focus in junctional escape rhythm.