Spontaneous neural activity of a mechanoreceptive system is undiminished by replacement of external calcium with equimolar magnesium in the presence of EGTA.
Spontaneous neural activity of a mechanoreceptive system is undiminished by replacement of external calcium with equimolar magnesium in the presence of EGTA.
复制标题
在 EGTA 存在的情况下，用等摩尔镁替代外部钙，机械感受系统的自发神经活动不会减弱。
DOI：
10.1016/0024-3205(87)90327-4
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发表时间：
1987
期刊：
影响因子：
6.1
通讯作者：
Drescher,MJ
中科院分区：
文献类型：
--
作者：
Drescher,DG;Drescher,MJ
侧线机械感觉器的初级传入神经元被认为与听觉和前庭器官密切相关，在没有机械刺激的情况下表现出自发的动作电位。正弦机械刺激毛细胞可提高传入神经元的脉冲率。当两种阳离子在另一种阳离子不存在的情况下变化时，自发活动被发现是随着外加镁或钙离子浓度的增加而递减的，并被施加于侧线机械感受器的突触侧。1 mM到6 mM的镁和5 mM的EGTA(后者用于螯合残留的钙离子)可以使晚期神经元的自发传入活动持续长达3到4小时。在沐浴加钙的情况下，机械刺激导致诱发的递增活动--定义为刺激后的总活动减去自发活动--随着钙浓度的增加而显著增加。然而，当浴缸中有镁和EGTA时，机械刺激在任何镁浓度下都不会使神经放电率高于自发放电率。综上所述，这些结果表明，与诱发的递增活动相比，自发活动不需要浴缸中的外部钙，自发神经动作电位的产生可能是通过修改经典的刺激-分泌耦合机制进行的。
Primary afferent neurons of the lateral-line mechanosensory organs, which are believed to be closely related to the auditory and vestibular organs, exhibit “spontaneous” action potentials in the absence of mechanical stimulation of the receptor cells (hair cells). Sinusoidal mechanical stimulation of the hair cells enhances the impulse rate of the afferent neurons. The spontaneous activity is found to be a decreasing function of increasing concentration of either external magnesium or calcium, when each cation is varied in the absence of the other and bath-applied to the synaptic side of the lateral-line mechanoreceptors. One mM to 6 mM magnesium with 5 mM EGTA (the latter for chelation of remaining traces of calcium) permits undiminished spontaneous afferent activity of later-line neurons for as long as 3 to 4 hours. With bath-applied calcium, mechanical stimulation results in evoked incremental activity - defined as total activity with stimulation minus spontaneous activity - which significantly increases with increasing calcium concentration. However, with magnesium and EGTA in the bath, mechanical stimulation produces no increase in the neural firing rate above spontaneous rate for any magnesium concentration tested. Taken together, these results suggest that spontaneous activity, in contrast to evoked incremental activity, does not require external calcium in the bath, and production of spontaneous neural action potentials may proceed via mechanisms that are modifications of those of classical stimulus-secretion coupling.