Waloga G, Pak W L
J Gen Physiol. 1978 Jan;71(1):69-92. doi: 10.1085/jgp.71.1.69.
The ionic mechanism of horizontal cell potentials was investigated in the isolated retina of the axolotl Ambystoma mexicanum. The membrane potentials of both receptors and horizontal cells were recorded intracellularly while the ionic composition of the medium flowing over the receptor side of the retina was changed. The membrane potential of the horizontal cell is highly depender side of the retina was changed. The membrane potential of the horizontal cell is highly dependent on the extracellular concentration of sodium. When the external ion concentration of either chloride or potassium was changed independently of the other, there were shifts in the membrane potential of the horizontal cell which could not be explained by changes in the equilibrium potential of these ions. If the external concentrations of both potassium and chloride ions were varied so that the product of their external concentrations did not change, the shift in the membrane potential of the horizontal cell was in the direction predicted by the Nernst equation. The results are consistent with the suggestion that in the dark the receptors release a synaptic transmitter which increases primarily the sodium conductance of the horizontal cell postsynaptic membrane.
在墨西哥钝口螈离体视网膜中研究了水平细胞电位的离子机制。在改变流过视网膜感受器一侧的介质离子组成时，细胞内记录感受器和水平细胞的膜电位。水平细胞的膜电位高度依赖于细胞外钠离子浓度。当单独改变氯化物或钾离子的外部离子浓度时，水平细胞膜电位会发生变化，而这些变化无法用这些离子平衡电位的改变来解释。如果同时改变钾离子和氯离子的外部浓度，使得它们外部浓度的乘积不变，那么水平细胞膜电位的变化方向符合能斯特方程的预测。这些结果与以下观点一致：在黑暗中，感受器释放一种突触递质，主要增加水平细胞突触后膜的钠电导。
