正常大鼠暗适应视网膜电图b波的光强-振幅曲线的观察

The luminance response function of the electroretinogram of the dark-adapted SD rat

目的观察正常SD大鼠暗适应视网膜电图b波光强-振幅曲线的特点。方法取完全暗适应状态SD大鼠12只。利用中性滤光片降低全视野刺激器固有光强度,按0.5个对数单位的间隔衰减得到7档(分别为-5.0、-4.5、-4.0、-3.5、-3.0、-2.5和-2.0log cd·s·m-2),采用RETI-scan系统,自制的银环角膜电极和不锈钢针状电极,记录暗适应系列光视网膜电图。采用Naka-Rushton方法分析b波的强度-反应函数。结果b波阈强度为-4.5log cd·s·m-2,饱和强度为-2.5log cd·s·m-2。当刺激强度在-5.0～-2.0log cd·s·m-2范围时,b波光强-振幅曲线呈"S"型,符合Naka-Rushton等式;其中有两个重要参数(Rmax,I50)分别代表b波饱和幅值和产生1/2该幅值的刺激强度,本实验中Rmax为(721.2±89.5)μV,I50为(-3.30±0.36)log cd·s·m-2。上述参数与人类正常值相比差异明显。结论大鼠视网膜反应特性与人类存在较大差异,应用视网膜电图b波光强-反应函数来评价其杆体系统功能时选择合适的刺激参数非常重要。

Objective To investigate the b -wave luminance response function of the scotopic electroretinogram in the normal SD rat. Methods Twelve dark-adapted SD rat eyes were included in the experiment. An original Ganzfeld light was spectrally filtered with a 500-nm interference filter to produce flashes that varied in intensity from -5.0～-2.0 log cd·s·m-2. ERGs to a series of flashes ranging in the intensities mentioned above were recorded with a RETI port system, silver loop electrode and stainless steel needle electrode. The Naka -Rushton equation was used to describe the b -wave luminance response function. Results The intensity that provided the b -wave threshold response and saturation measured -4.5 and -2.5 log cd·s·m-2, respectively. The b-wave amplitudes were plotted as an S -shaped curve with an increase in intensity from -5.0 to -2.0 log cd·s·m^-2. The relationship between them could be plotted using a hyperbolic saturation function （Naka-Rushton function）. The model yielded 2 often-used parameters, Rmax and scotopic I50, representing the asymptotic b wave amplitude and the intensity that provided half saturation. In this experiment , Rmax measured （721.2 ± 89.5） μV and I50 measured （-3.30 ±0.36） log cd·s·m^-2. Conclusion The electrophysiological characteristics of the rat are different from humans. Thus proper stimulation intensities must be adopted when using b -wave luminance response functions to evaluate the retina of the rat.