Activity-dependent changes in conduction velocity in the olfactory nerve of the tortoise
Activity-dependent changes in conduction velocity in the olfactory nerve of the tortoise
复制标题
陆龟嗅神经传导速度的活动依赖性变化
DOI：
10.1007/bf00583251
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
M. E. Rosenberg
中科院分区：
文献类型：
--
作者：
T. Bliss;M. E. Rosenberg
摘要1.陆龟嗅神经复合动作电位的传导速度受先前活动的影响。首先，传导速度与由刺激速率确定的活动水平之间存在反比关系。第二，在活动的神经中，虽然不是在静息的神经中，由一对电击中的第二个引发的动作电位比第一个引发的动作电位传导得快。在第一次反应的尾流中建立的超常传导速度的周期持续约1 s，在效应的峰值处传导速度增加高达27%。哇巴因和在洗浴介质中用锂代替钠会减弱超常态的程度;当用硫酸盐代替氯化物时，超常态的程度会增强。3.增加条件性齐射次数不能增强超常态。在超常期的高峰期达到的传导速度通常与静息神经的传导速度一样大，但从未超过静息神经的传导速度。4.这些结果以及基于Hodgkin-Huxley方程的计算结果表明，传导速度对刺激速率的依赖性反映了细胞内钠水平对活动的相应依赖性。两类解释超常被认为是，一个基于激活的产电泵，和其他的钠电导的瞬时增加。现有的证据不足以区分这两种假设。
Abstract1.The conduction velocity of the compound action potential in the olfactory nerve of the tortoise is affected by previous activity in two ways. First, there is an inverse relation between conduction velocity and the level of activity as determined by the rate of stimulation. Second, in the active, though not in the resting nerve, the action potential initiated by the second of a pair of shocks is conducted faster than that initiated by the first. The period of supernormal conduction velocity set up in the wake of the first response lasts for about 1 s, and at the peak of the effect conduction velocity is increased by up to 27%.2.Aspects of these phenomena were investigated in vitro. The magnitude of supernormality was diminished by ouabain, and by the substitution of lithium for sodium in the bathing medium; it was enhanced when chloride was replaced by sulphate.3.Supernormality could not be potentiated by increasing the number of conditioning volleys. The conduction velocity achieved at the peak of the supernormal period was usually as great as, but never greater than the conduction velocity of the resting nerve.4.These results, together with the results of computations based on the Hodgkin-Huxley equations, suggest that the dependence of conduction velocity on the rate of stimulation is a reflection of a corresponding dependence of intracellular sodium levels on activity. Two classes of explanation for supernormality are considered, one based on the activation of an electrogenic pump, and the other on a transient increase in sodium conductance. The available evidence is insufficient to distinguish between these two hypotheses.