迷走和交感神经对蟾蜍心室肌细胞跨膜电位的影响

为观察迷走和交感神经对蟾蜍心室肌细胞跨膜电位的影响,以微电极技术引导心室肌细胞电位。迷走神经刺激时,静息电位增大,复极过程加速。若事先注射阿托品,上述现象消失。交感神经刺激时,动作电位增大,但静息电位保持不变,因此主要是由于超射增加所致。交感神经刺激,尽管使心率加快,动作电位时程缩短,但动作电位的平台期却延长。这些结果提示,迷走和交感神经对心室肌细胞跨膜电位的影响具有协调性,并共同维持着跨膜电位的正常特性。

Effects of Vagal and Sympathetic Nerves on Transmembrane Potential of Cardiac Ventricular Cells of Toad

The effects of vagal and sympathetic nerves on the transmembrane potentials of cardiac ventricular cells of toad were observed. The transmembrane potentials were recorded with floating microelectrode technique. Vagal stimulation caused an increase in resting potential and an acceleration in repolarization of action potential (AP). When pretreated with atropine these phenomena were abolished. As soon as the sympathetic nerve was stimulated,AP amplitude increased; but resting potential remained the same, The increase of AP was therefore due to the increases of overshoot. Although heart rate increased and duration of AP shortened while stimulating sympathetic nerve, the plateau phase of AP was prolonged. These results suggest that the effects of vagal and sympathetic nerves on the transmembrane potential of cardiac ventricular cells are coordinate and the normal characteristics of transmembrane potential are maintained by both the vagal and sympathetic nerves.