Effects of divalent cations on the frequency of spontaneous action potentials from the lateral line organ of Xenopus laevis.
Effects of divalent cations on the frequency of spontaneous action potentials from the lateral line organ of Xenopus laevis.
复制标题
二价阳离子对非洲爪蟾侧线器官自发动作电位频率的影响。
DOI：
10.1016/0006-8993(90)91120-6
复制
发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Drescher,DG
中科院分区：
文献类型：
--
作者：
Guth,SL;Drescher,DG
用含Co ~（2+）、Ca ~（2+）、Mg ~（2+）、Ba ~（2+）的生理盐水灌流非洲爪蟾皮肤内表面，观察其对侧线神经自发动作电位频率的影响，以探讨细胞外Ca ~（2+）在神经自发活动中的作用。二价阳离子添加到青蛙盐水，无论是单独或作为两种不同的离子的混合物，产生浓度依赖性抑制的自发速率。单独灌注时，各离子的抑制效力顺序为Co 2 +> Ca 2 +> Mg 2 +> Ba 2+。Mg 2+和Co2+，或Ca 2+和Co2+的组合的抑制，近似于每种阳离子的抑制作用的总和。当这些离子中的每一种与相同量的Co 2+配对时，Ca 2+比Mg 2+更具有抑制性，而当与Mg 2+类似地配对时，Ca 2+与Co 2+大致一样具有抑制性。一种解释的抑制由Ca 2+调用的假设，二价阳离子抑制自发活动的电压敏感的Na+通道的传入树突的电荷屏蔽和释放的神经递质的细胞外Ca 2+通过电压敏感的Ca 2+通道的毛细胞的流入可能不是唯一的机制产生的自发活动的侧线。这些结果量化了侧线常见二价阳离子的相对抑制效力，并作为一个警告，调查人员解释了高浓度的Co 2+或Mg 2+作为神经传递依赖于细胞外Ca 2+的充分证据的动作电位的封锁，特别是在acousticolateralis系统。
The effect of superfusion of the internal surface of the skin ofXenopus laeviswith saline containing Co2+, Ca2+, Mg2+, or Ba2+, on the frequency of spontaneous action potentials of the lateral line nerve, was studied to investigate the role of extracellular Ca2+in spontaneous neural activity. Addition of divalent cations to frog saline, either singly or as a mixture of two different ions, produced concentration-dependent suppression of spontaneous rate. The rank order of potency for suppression by each ion, perfused alone, was Co2+> Ca2+> Mg2+> Ba2+. Suppression by combinations of Mg2+and Co2+, or of Ca2+and Co2+, was approximated by the sum of the suppressive effects of each cation. Ca2+was more suppressive than Mg2+when each of these ions was paired with the same amount of Co2+, while Ca2+was approximately as suppressive as Co2+when similarly paired with Mg2+. One interpretation of the suppression by Ca2+invokes the hypothesis that divalent cations suppress spontaneous activity by charge screening of voltage-sensitive Na+channels on afferent dendrites and that release of neurotransmitter by the influx of extracellular Ca2+through voltage-sensitive Ca2+channels of hair cells may not be the sole mechanism for generation of spontaneous activity in the lateral line. These results quantify the relative suppressive potency of common divalent cations in the lateral line, and serve as a caveat to investigators who interpret a blockade of action potential by high concentrations of Co2+or Mg2+as sufficient evidence for dependence of neurotransmission upon extracellular Ca2+, particularly in acousticolateralis systems.