Djamgoz M B, Laming P J
Department of Pure and Applied Biology, Imperial College, London, England.
Vision Res. 1987;27(5):711-21. doi: 10.1016/0042-6989(87)90068-x.
Extracellular and intracellular K+ activities of luminosity and biphasic-chromaticity type horizontal cells were measured in non-superfused roach retinae using double-barrelled K+-sensitive micro-electrodes. The extracellular K+ activity in dark-adapted retinae was 3.4 mM on average. The intracellular K+ activities of the two types of horizontal cell in the dark were very similar (57 and 54 mM, respectively), and corresponding values of the K+ equilibrium potential were about 35 mV more negative than respective resting potentials. During light-evoked hyperpolarizations, the intracellular K+ activity decreased, and at saturation, resting potentials matched corresponding K+ equilibrium potentials. The results are discussed in relation to sub-synaptic and non-synaptic membrane ionic mechanisms and further support the view that the non-synaptic membrane is selectively permeable to K+.
使用双管钾离子敏感微电极，在未进行超灌流的蟑螂视网膜中测量了发光型和双相色度型水平细胞的细胞外和细胞内钾离子活性。暗适应视网膜中的细胞外钾离子活性平均为3.4 mM。两种类型的水平细胞在黑暗中的细胞内钾离子活性非常相似（分别为57 mM和54 mM），钾离子平衡电位的相应值比各自的静息电位负约35 mV。在光诱发的超极化过程中，细胞内钾离子活性降低，在饱和时，静息电位与相应的钾离子平衡电位匹配。结合突触后和非突触膜离子机制对结果进行了讨论，并进一步支持了非突触膜对钾离子具有选择性通透性的观点。
