Djamgoz M B
Department of Pure and Applied Biology, Neurobiology Group, Imperial College, London, U.K.
Physiol Bohemoslov. 1988;37(3):235-9.
The effect of L-glutamate on extracellular K+ activity (aK0) in the micro-environment of the isolated retina of a cyprinid fish was investigated using double-barrelled K+-sensitive micro-electrodes. Glutamate was pulsed onto the retina from an atomizer, and aK0's recorded at different retinal depths. Glutamate induced a concentration-dependent rise in aK0 which was maximal in the first 100 microns of the retinal surface. The aK0 change was transient, with a time to peak of 20-30 s, and complete reversal within 4 min. However, if the retina was pre-treated with dinitrophenol or ouabain, the maximum rise in aK0 was greater than normal, and the effect was sustained. Application of equimolar glutamate transiently depolarized the membrane potentials of horizontal cells. The effects of glutamate on aK0 and horizontal cell membrane potential had some common characteristics. It is concluded that glutamate may have non-synaptic effects on post-receptoral retinal neurones, and possible mechanisms of this are considered.
利用双管钾离子敏感微电极，研究了L-谷氨酸对鲤科鱼类离体视网膜微环境中细胞外钾离子活性（aK0）的影响。谷氨酸从雾化器脉冲施加到视网膜上，并在不同视网膜深度记录aK0。谷氨酸诱导aK0浓度依赖性升高，在视网膜表面的前100微米处达到最大值。aK0变化是短暂的，达到峰值的时间为20 - 30秒，并在4分钟内完全恢复。然而，如果视网膜用二硝基苯酚或哇巴因预处理，aK0的最大升高幅度大于正常情况，且这种效应持续存在。等摩尔谷氨酸的应用使水平细胞的膜电位短暂去极化。谷氨酸对aK0和水平细胞膜电位的影响具有一些共同特征。得出结论，谷氨酸可能对视网膜后受体神经元有非突触作用，并考虑了其可能的机制。
