Attwell D, Wilson M, Wu S M
Brain Res. 1985 Sep 16;343(1):79-88. doi: 10.1016/0006-8993(85)91160-6.
Adjacent rods in the amphibian retina are electrically coupled to each other by gap junctions. By injecting current pulses into one rod and recording the voltage change produced in nearby rods, we have studied the extent to which signals spread between rods in the presence and absence of illumination. Light has little effect on the steady potentials produced in nearby rods by the injection of a hyperpolarizing current, but does affect the propagation of transient signals through the rod network. The responses to injection of depolarizing current are increased by light. These effects of light were mimicked by hyperpolarizing the rod network (non-uniformly) by injecting continuous current (on top of which current pulses were superimposed to monitor signal spread). This suggests that the effects of light are due solely to the rod hyperpolarization produced by light. The effects of light are not completely predicted from computer simulations based on a previous characterization of the properties of isolated rods; these experiments thus reveal an inadequacy in the description of the rod membrane currents in that model. Light-induced hyperpolarization of cones has no effect on signal spread between rods. The functional significance of these results is discussed.
两栖动物视网膜中的相邻视杆细胞通过缝隙连接彼此电耦合。通过向一个视杆细胞注入电流脉冲并记录附近视杆细胞产生的电压变化，我们研究了在有光和无光情况下信号在视杆细胞之间传播的程度。光对通过注入超极化电流在附近视杆细胞中产生的稳定电位影响很小，但确实会影响瞬态信号在视杆细胞网络中的传播。光会增强对视杆细胞注入去极化电流后的反应。通过注入连续电流（在其上叠加电流脉冲以监测信号传播）使视杆细胞网络（非均匀地）超极化，模拟了光的这些效应。这表明光的效应完全是由于光产生的视杆细胞超极化所致。基于之前对分离视杆细胞特性的表征进行的计算机模拟并不能完全预测光的效应；因此，这些实验揭示了该模型对视杆细胞膜电流描述的不足之处。光诱导的视锥细胞超极化对视杆细胞之间的信号传播没有影响。本文讨论了这些结果的功能意义。
