The skate retina provides a native all-rod retina suited for investigating a single type of photoreceptor regarding its properties and signaling to second order cells. Using the aspartate-induced isolated A-wave of the skate eyecup electroretinogram (ERG), it has been shown that adaptation in rods remains Weber-Fechner-like over a 6-log unit increase in background light intensity. Zinc, which can block calcium channels, has been found in the rod synaptic terminal and the synaptic cleft. Histidine is a zinc chelator. Voltage signals from neurons post-synaptic to rods indicate that histidine increases the dark release of glutamate and increases the horizontal cell light response. In histidine, the A-wave response to various light intensities in the dark-adapted retina increased more than fifty percent, corresponding to the effect on horizontal cells. In the presence of background light, although histidine-treated rod light responses remained Weber-Fechner-like, their increment threshold was raised significantly. This indicates that endogenous zinc feedback serves to increase rod sensitivity in a light-adapted retina, despite a corresponding reduction of threshold sensitivity in the dark. We propose that the increase in A-wave amplitude is a result of the increased conductance at the synaptic terminal and that the A-wave can be used to monitor changes in rod transmitter release. Furthermore, endogenous zinc may also provide the benefit of reducing metabolic stress and the risk of glutamate toxicity in the dark.

滑板视网膜提供了一种原生的全视杆视网膜，适用于研究单一类型的光感受器，了解其特性和向二级细胞发出的信号。使用天冬氨酸诱导的滑板眼杯视网膜电图 (ERG) 的孤立 A 波，已经表明，在背景光强度增加 6 个对数单位时，视杆中的适应仍然类似于 Weber-Fechner。在杆状突触末端和突触间隙中发现了可以阻断钙通道的锌。组氨酸是一种锌螯合剂。从突触后神经元到视杆细胞的电压信号表明组氨酸增加了谷氨酸的暗释放并增加了水平细胞光反应。在组氨酸中，暗适应视网膜中对各种光强度的 A 波反应增加了 50% 以上，这与对水平细胞的影响相对应。在背景光存在的情况下，虽然组氨酸处理的棒状光反应仍然与 Weber-Fechner 相似，但它们的增量阈值显着提高。这表明内源性锌反馈有助于提高光适应视网膜的视杆细胞敏感性，尽管在黑暗中相应降低了阈值敏感性。我们建议 A 波振幅的增加是突触末端电导增加的结果，并且 A 波可用于监测杆发射器释放的变化。此外，内源性锌还可以提供减少代谢压力和黑暗中谷氨酸毒性风险的好处。这表明内源性锌反馈有助于提高光适应视网膜的视杆细胞敏感性，尽管在黑暗中相应降低了阈值敏感性。我们建议 A 波振幅的增加是突触末端电导增加的结果，并且 A 波可用于监测杆发射器释放的变化。此外，内源性锌还可以提供减少代谢压力和黑暗中谷氨酸毒性风险的好处。这表明内源性锌反馈有助于提高光适应视网膜的视杆细胞敏感性，尽管在黑暗中相应降低了阈值敏感性。我们建议 A 波振幅的增加是突触末端电导增加的结果，并且 A 波可用于监测杆发射器释放的变化。此外，内源性锌还可以提供减少代谢压力和黑暗中谷氨酸毒性风险的好处。