Popova E, Kupenova P, Vitanova L, Mitova L
Department of Physiology, High Medical Institute, Sofia, Bulgaria.
Acta Physiol Scand. 1995 Jul;154(3):377-86. doi: 10.1111/j.1748-1716.1995.tb09921.x.
The intensity-response (V/log I) function of ERG OFF response (d-wave) in dark and light adapted superfused frog eyecups was investigated before and after blockade of the retinal ON channel by 2-amino-4-phosphonobutyrate (APB). The V/log I function of the dark adapted d-wave had two distinct components, each of them consisting of an ascendent and descendent part. In eyes adapted to mesopic or photopic background the V/log I function had only one component. It was shifted to the right along the intensity axis, had a steeper slope and a higher maximal response amplitude compared with the two components of the dark-adapted V/log I curve. Perfusion with 200 mumol APB markedly increased the d-wave amplitude at all stimulus intensities except for the threshold ones in both dark and light adapted eyes. The position of the V/log I curve was shifted slightly to the left along the intensity axis in dark adapted eyes, but was not changed in light adapted eyes. Thus the adaptational mechanism responsible for changes in the decremental sensitivity with increased background illumination was not altered by APB. The effect of APB was studied also in chromatically adapted eyes, in which the responses were predominantly mediated by one photoreceptor type. The results showed that the potentiating effect of APB on d-wave did not depend on photoreceptor input.
在通过2-氨基-4-膦酰丁酸（APB）阻断视网膜ON通道之前和之后，研究了暗适应和明适应的灌注蛙眼杯状细胞中ERG OFF反应（d波）的强度-反应（V/log I）函数。暗适应d波的V/log I函数有两个不同的成分，每个成分都由一个上升部分和一个下降部分组成。在适应于中间视觉或明视觉背景的眼睛中，V/log I函数只有一个成分。与暗适应V/log I曲线的两个成分相比，它沿强度轴向右移动，斜率更陡，最大反应幅度更高。用200 μmol APB灌注在除暗适应和明适应眼睛中的阈值强度外的所有刺激强度下均显著增加了d波幅度。在暗适应眼睛中，V/log I曲线的位置沿强度轴略微向左移动，但在明适应眼睛中没有变化。因此，APB没有改变随着背景光照增加而导致递减敏感性变化的适应机制。还在颜色适应的眼睛中研究了APB的作用，其中反应主要由一种光感受器类型介导。结果表明，APB对d波的增强作用不依赖于光感受器输入。
