家兔房室隔内过渡细胞束的形态学及细胞动作电位特征

Characteristics of the Morphology and Cellular Action Potential of the Transitional Cellular Bundles in Rabbits Atrioventricular Septum

为研究房室隔形态学特点和细胞电生理学特性 ,选用 10只家兔做房室隔连续切片观察形态学特征后 ,在 30只家兔房室隔标本上 ,利用标准玻璃微电极技术引导细胞动作电位 (AP) ,配合微电泳技术等方法对所记录细胞进行定位判断。结果 :①光镜下 ,房室隔内可见三条主要由过渡细胞 (TC)组成的房结束 (ANBs) ,向前延续成一大束TC束 ,为结后延伸 (PNE) ,其与AVN后端自然延续。②PNE及ANBs中TC的AP特性与AVN细胞相似 ,最大舒张电位 (MDP)负值 (- 6 2± 4 ,- 6 3± 9,- 6 2± 6mV)小于普通右房肌细胞 (- 70± 6mV ,P <0 .0 5 ) ;动作电位幅度 (APA)较低 ;0期最大上升速度 (Vmax) (19± 2 ,18± 1,14± 1V/s)明显慢于普通右房肌细胞 (93± 2V/s,P <0 .0 1) ;有 4期缓慢自动除极 ,但PNE及ANBs中TC的 4期自动除极速度 (V4) (5 7± 4 ,5 7± 1mV/s)明显慢于AVN细胞 (92± 5mV/s,P<0 .0 5 )。结论 :①PNE、ANBs中TC有自律性 ,传导性低。②结合形态学特点 ,认为PNE和ANBs共同参与房室交界区大折返环路中的慢径传导。

To investigate the properties of the morphology and cellular action potential(AP)of the atrioventricular septum by using serial sections and standard glass electrode method. The positions recorded AP were ascertained by tissue slicing after microelectrophoresis or retaining a broken microelectrode tip. Results:①In the light microscopy,Three smaller transitional cellular bundles called atrial nodal bundles(ANBs)respectively come from the anterior,inferior of the coronary sinus orifice (CSO) and the posterior wall of the left atrium.They linked forward to the posterior nodal extension (PNE) composed of a large transitional cellular bundle and the PNE linked forward to the AV node.②The AP characteristics of the transitional cells (TC) of PNE and ANBs are similar to that of the AV node cell.Their MDP (-62±4,-63±9,-62±6 mV) are less negative than that of the ordinary right atrial myocytes (-70±6mV,P<0.05). Their Vmax (19±2,18±1,14±1V/s) are slower than that of the ordinary right atrial myocytes (93±2V/s,P<0.01). they all have a spontaneous phase 4 depolarization, But the V 4 of the transitional cells of PNE and ANBs (57±4,57±1 mV/s) are slower than that of the AV node cell(92±5mV/s,P<0.05).Conclusions: The transitional cells of PNE and ANBs had a automatism and a slower conductivity. Thus, the PNE and ANBs maybe provided a substrate for the slow pathway conduction.