Carretta M, Grassi S, Magni F
Arch Ital Biol. 1981 May;119(2):160-77.
Electrical stimulation of the ventral cord of H. medicinalis elicits in both Retzius' cells of each segmental ganglion an EPSP which is composed by an early and a late component. The early EPSP is electrical in nature, since it is unaffected by displacements of the membrane potential and by high Mg2+, whereas the late one is chemical, being reversed in sign by membrane depolarization and suppressed by high Mg2+. Latency measurements show that the electrical and chemical EPSP components are mediated by two different pathways characterized by conduction velocities of 0.5 and 0.3 m/sec respectively. Both pathways run in each of the lateral connectives and propagate impulses in anterior and posterior direction. Collision experiments show that ascending and descending impulses along the pathway mediating the electrical EPSP travel along the same fibres. Separate stimulation of the lateral connectives and selective inactivation of one Retzius' cell show that both pathways converge onto each Retzius' cell show that both pathways converge onto each Retzius cell. The possible functional significance of the two excitatory pathways is discussed.
对药用蛭腹神经索进行电刺激，会在每个节段神经节的雷丘斯细胞中引发一个兴奋性突触后电位（EPSP），该电位由一个早期成分和一个晚期成分组成。早期EPSP本质上是电性质的，因为它不受膜电位变化和高镁离子浓度的影响，而晚期EPSP是化学性质的，其电位符号会因膜去极化而反转，并被高镁离子抑制。潜伏期测量表明，电性质和化学性质的EPSP成分由两条不同的通路介导，其传导速度分别为0.5米/秒和0.3米/秒。这两条通路在每条侧索中都存在，并能向前和向后传播冲动。碰撞实验表明，沿介导电EPSP的通路向上和向下传播的冲动沿着相同的纤维传导。分别刺激侧索并选择性使一个雷丘斯细胞失活，结果表明两条通路都汇聚到每个雷丘斯细胞上。文中讨论了这两条兴奋性通路可能的功能意义。
