Postsynaptic electrogenesis in septate giant axons. II. Comparison of medial and lateral giant axons of crayfish.
Postsynaptic electrogenesis in septate giant axons. II. Comparison of medial and lateral giant axons of crayfish.
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分隔巨轴突的突触后电发生。
DOI：
10.1152/jn.1960.23.6.618
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发表时间：
1960
影响因子：
2.5
通讯作者：
C. Kao
中科院分区：
文献类型：
--
作者：
C. Kao
1.膜电位。间隔外侧纤维和非间隔内侧纤维的静息和动作电位基本相同。静息电位范围为70~90 mV(平均80.75 mV，SD+5.67 mV)，显著高于报道的龙虾巨型轴突(16 MV)。波幅10 4~139 mV(平均118.25，SD+11.18 mV)，反向电位2 2~5 8 mV(平均37.5 0，SD+10.39 mV)。在针刺时记录到的高棘波幅度通常保持长达六个小时，而且经常在同一轴突的不同部分重复刺入之后也是如此。这两种类型的纤维的尖峰幅度达到峰值的时间约为0.3毫秒，但与其他轴突一样，下降阶段持续的时间更长，占据了略高于1毫秒的尖峰持续时间的剩余部分。这两种神经的反应在其晚期不同，内侧巨大轴突的棘向静息电位下沉，而外侧纤维保持轻微去极化，持续15毫秒。或更长(图2B，d)。这一阶段比蚯蚓中巨轴突类似的后除极化作用要大得多，持续时间也更长。在某种程度上，这种去极化可能代表了与棘波相关的后电位，但对它的一些贡献来自突触后电位，如下所述。两种类型的轴突在棘波后都没有表现出超极化阶段。
1. Membrane potentials. The resting and action potentials of the septate lateral and non-septate medial fibers were essentially identical. The resting potentials ranged from 70 to 90 mV.(mean 80.75, SD+ 5.67 mV.), valuessignificantly higher than those reported for the giant axons of lobster (16). Spike amplitudes varied from 104 to 139 mV.(mean 118.25, SD+ 11.18 mV.), the reversed potentials ranging from 22 to 58 mV.(mean 37.50, SD+ 10.39 mV.). High spike amplitudes recorded at the time of impalementwere often maintained for periods as long as six hours, and frequently also after repeated impalements in various parts of the same axon. The time to peak amplitudes of the spikes in both types of fibers was about 0.3 msec., but the falling phase, as in other axons, was longer-lasting and occupied the remainder of the spike duration of slightly more than 1 msec. The responses of the two types of nerves differed in their later phase, the spike of the medial giant axon subsiding to the resting potential, while the lateral fibers remained slightly depolarized for 15 msec. or longer (Fig. 2b, d). This phase is considerably larger and longer-lasting than similar after-depolarization of the earthworm median giant axon. In part, this depolarization probably represents an after-potential associated with the spike, but some contribution to it was derived from postsynaptic potentials as will be described below. Neither type of axon exhibited a phase of hyperpolarization after the spike.