Popova E, Penchev A
Department of Pathology, Medico-Biological Institute, Medical Academy, Sofia, Bulgaria.
Biomed Biochim Acta. 1990;49(10):1005-13.
The effect of GABAergic blockade on the intensity-response function of frog ERG waves was investigated under two levels of background illumination in the mesopic and photopic range. GABAergic blockade by picrotoxin shifted the intensity-response curves to the left along the intensity axis and increased their slope under both backgrounds. The maximal gain (dV/dI) and contrast gain (dV/dlog I) of the mechanisms responsible for the ERG wave generation were also increased after GABAergic blockade. The intensity range in which the amplitude of the response was a linear function of the logarithm of the stimulus intensity was very restricted. GABAergic blockade influenced also the rapid transitory processes, which determined the steady-state amplitude of the ERG b-wave after a considerable change of the stimulus contrast. The adaptational effect of the background illumination on the intensity-response function of the ERG waves was not principally changed after GABAergic blockade. The possible neuronal mechanisms of the observed picrotoxin effects are discussed.
在中视觉和明视觉范围内的两种背景光照水平下，研究了GABA能阻断对青蛙视网膜电图（ERG）波强度-反应函数的影响。印防己毒素引起的GABA能阻断使强度-反应曲线沿强度轴向左移动，并在两种背景下均增加了其斜率。GABA能阻断后，负责ERG波产生的机制的最大增益（dV/dI）和对比度增益（dV/dlog I）也增加了。反应幅度是刺激强度对数的线性函数的强度范围非常有限。GABA能阻断还影响了快速瞬态过程，这些过程决定了刺激对比度发生相当大变化后ERG b波的稳态幅度。GABA能阻断后，背景光照对ERG波强度-反应函数的适应性影响没有发生主要变化。文中讨论了所观察到的印防己毒素效应可能的神经元机制。
