Wu S M, Yang X L
Cullen Eye Institute, Baylor College of Medicine, Houston, TX 77030.
Proc Natl Acad Sci U S A. 1988 Jan;85(1):275-8. doi: 10.1073/pnas.85.1.275.
Electrical coupling between rods and cones was studied in the salamander (Ambystoma tigrinum) retina by measuring the light responses and spectral sensitivities of rods and cones and by measuring the voltage responses from a rod to current pulses injected into a cone. A population of 10-20% of the photoreceptors exhibited a mixed-response waveform of the rod and the cone under dark-adapted conditions, and a response waveform closely resembled that of a cone in the presence of background illumination. Lucifer yellow injection revealed that these cells are morphologically identical to rods, and thus they are named rodcs. Dark-adapted rodcs exhibited a rod-like spectral sensitivity with a peak at approximately 520 nm that shifted to a cone-like spectral sensitivity with a peak at approximately 620 nm in response to background light (Purkinje shift). The voltage response of a rodc to a -1-nA current step injected into an adjacent cone is approximately 3.6 times larger than that of a rod to the same current step. These results indicate that there is a population of rods (rodcs) in the tiger salamander retina that is strongly coupled to the cones and that these cells allow significant mixture of rod and cone signals at the photoreceptor level.
通过测量蝾螈（虎纹钝口螈）视网膜中视杆细胞和视锥细胞的光反应及光谱敏感性，以及测量向视锥细胞注入电流脉冲时视杆细胞的电压反应，对视杆细胞和视锥细胞之间的电耦合进行了研究。在暗适应条件下，10%-20%的光感受器群体表现出视杆细胞和视锥细胞的混合反应波形，在有背景光照时，反应波形与视锥细胞的非常相似。荧光黄注射显示，这些细胞在形态上与视杆细胞相同，因此被命名为视杆-视锥细胞（rodcs）。暗适应的视杆-视锥细胞表现出类似视杆细胞的光谱敏感性，峰值约在520nm，在背景光作用下（浦肯野位移），峰值转移到约620nm的类似视锥细胞的光谱敏感性。视杆-视锥细胞对注入相邻视锥细胞的-1nA电流阶跃的电压反应大约是视杆细胞对相同电流阶跃的电压反应的3.6倍。这些结果表明，虎纹钝口螈视网膜中存在一群与视锥细胞紧密耦合的视杆细胞（视杆-视锥细胞），并且这些细胞在光感受器水平上允许视杆细胞和视锥细胞信号大量混合。
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