Djamgoz M B, Petruv R, Yasui S, Furukawa T, Yamada M
Department of Biology, Imperial College of Science, Technology and Medicine, London, UK.
Neurosci Res. 1998 Jan;30(1):13-24. doi: 10.1016/s0168-0102(97)00107-7.
Chromatic aspects of receptive field size in the H1 horizontal cell syncytium of the carp retina were investigated using spectral photostimuli (blue or red) presented in the form of either a pair of a small spot and annulus, or a narrow moving slit. In the light-adapted retina, the receptive field for the blue stimulus was found to be significantly smaller than that for the red, i.e. there was a chromatic difference in the receptive field size. During the course of dark adaptation, the overall receptive field size increased, but the chromatic difference decreased. Immediately after adaptation to bright light, the receptive field sizes were reduced significantly, but the chromatic difference increased, mainly due to a greater reduction in the receptive field for the blue stimulus. Application of dopamine (5 microM) to a dark-adapted retina gradually decreased the receptive field size for both colours, but the chromatic difference became larger, again due to a greater reduction in the receptive field size for the blue stimulus. 2-Amino-4-phosphonobutyrate (APB) applied to light-adapted retinae at a working concentration of 1 mM, greatly expanded the receptive field size and suppressed the chromatic difference due to the effect being greater for the receptive field for the blue stimulus. The effect of APB was slow and cumulative. On the other hand, intracellular injection of cGMP or dibutyryl-cGMP increased the chromatic difference in the receptive field size. It is suggested (i) that the chromatic difference in the receptive field size could be due to a cGMP-coupled, conductance-decreasing receptor mechanism activated by APB; and (ii) that the mechanism is associated with short-wavelength sensitive cone input to the H1 cells and operates in the light-adapted state of the retina.
利用呈小点和圆环对或窄移动狭缝形式的光谱光刺激（蓝色或红色），研究了鲤鱼视网膜H1水平细胞合胞体中感受野大小的色度方面。在光适应视网膜中，发现蓝色刺激的感受野明显小于红色刺激的感受野，即感受野大小存在色度差异。在暗适应过程中，整体感受野大小增加，但色度差异减小。刚适应强光后，感受野大小显著减小，但色度差异增加，这主要是由于蓝色刺激的感受野减小幅度更大。将多巴胺（5微摩尔）应用于暗适应视网膜会逐渐减小两种颜色的感受野大小，但色度差异会变大，同样是因为蓝色刺激的感受野大小减小幅度更大。以1毫摩尔的工作浓度将2-氨基-4-磷酸丁酸（APB）应用于光适应视网膜时，会极大地扩大感受野大小并抑制色度差异，因为对蓝色刺激的感受野影响更大。APB的作用缓慢且具有累积性。另一方面，细胞内注射cGMP或二丁酰-cGMP会增加感受野大小方面的色度差异。有人提出：（i）感受野大小的色度差异可能归因于由APB激活的cGMP偶联、电导降低的受体机制；（ii）该机制与H1细胞的短波长敏感视锥输入相关，并在视网膜的光适应状态下起作用。
