兔心房室隔过渡细胞的传导性及其电生理基础

目的　探索过渡细胞电生理特性与形态特征间的内在联系。方法　选 10只家兔做房室隔水平面及矢状面连续切片 ,HE染色观察。另 2 0只家兔采用标准玻璃微电极技术测定房室隔区正向传导速度。结果　房室结后方有两束过渡纤维分别延续至冠状窦口及其下方 ,分别为右后房结束和右下房结束 ,传导速度分别为 (0 .0 5 9± 0 .0 18)m·s-1和(0 .0 5 8± 0 .0 15 )m·s-1(P >0 .0 5 )。界嵴下段普通房肌传导速度为 (0 .2 0 3± 0 .0 4 0 )m·s-1。与前两者间均有显著性差异 (P <0 .0 1)。另外 ,过渡细胞动作电位有 4期自动除极 ,最大舒张电位 (- 6 3± 6 )mV ,普通房肌细胞无 4期自动除极 ,静息电位 (- 72± 4 )mV ,两者有显著性差异 (P <0 .0 5 )。结论　过渡细胞属慢反应自律细胞 ,传导速度比普通房肌慢。

Electrophysiological study on the conductivity of transitional cell in atrioventricular septum in rabbits and its morphologic basis

Objective To investigate the potential relation between electrophysiologic and morphologic properties of the transitional cell (T cell). Methods Tissues of 10 rabbits from atrioventricular junction region were observed by serial section under light microscope first. Another 20 hearts were selected to study the conduction velocity of transitional fibers in this area using standard microelectrode techniques. Results Two transitional cellular bundles were found to link forward with the atrioventricular node (AVN) from the coronary sinus ostium and the inferior, which are called the right post atrial node bundle and the right inferior atrial node bundle. Their conduction velocity was (0.059±0.018) m·s -1 and (0.058±0.015)m·s -1 (P> 0.05). They were both slower than the CV of the inferior terminal crest (0.203±0.040) m·s -1 (P< 0.01). The transitional cell had spontaneous depolarization in the 4 th phase of the action potential and had a maximum diastolic potential (-63±6) mV which was less negative than the resting membrance potential (RMP) of atrial cell (-72±4)mV (P< 0.05). Conclusion The transitional cell may be a kind of slow-reaction cell with automatism frequency. It has a low conduction velocity.