Functional study of the olfactory sensory signal transduction mechanism using the optic fiber system for optically monitoring membrane potential.

我们建立了一种用光导纤维监测膜电位的光学方法，并测量了电刺激内侧嗅束后大鼠嗅球上的电活动。嗅球用电压敏感染料染色。Y型光纤是根据我们的特殊要求制作的，在为放置准备物而设计的一个边缘接收两种光纤：一种连接到光罩，另一种连接到光电探测器。照明由100 W钨卤素灯提供，该灯由稳定的直流电源以稳定电流模式驱动。使入射光通过535 * 40 nm干涉滤光片，以适合电压敏感染料的峰值激发波长。在光电探测器中的光纤和光电二极管之间，我们放置了一个彩色玻璃滤光片。这种滤光片能很好地透过染料的长波长荧光，但却阻挡了短波长的激发光。RH-414的光信号尺寸非常大，但是，由于该染料具有一定的光毒性效应并且快速漂白，因此其不适合于我们相对长时间的实验。用其他三种染料染色的制剂没有发现任何毒性作用，但信号大小很小，需要对信号进行平均以分析波形。我们假设光信号也检测到除了直接膜电位变化之外的一些变化（可能是由于制剂的体积变化），但是与电刺激同步。

We have developed optical method for monitoring the membrane potential using optic fibers and measured the electrical activity on the rat olfactory bulb following the antidromic electric stimulation of the medial olfactory tract. The olfactory bulb was stained by the voltage-sensitive dye. The Y-shaped optic fibers were made at our special request One edge designed for putting on the preparation received two kinds of optic fibers : one was connected to light housing and another to photodetector. Illumination was provided by a 100 W tungsten-halogen lamp driven by a stable DC power supply at steady current mode. Incident light was passed through a 535 * 40 nm interference filter so as to fit the peak excitation wavelength for the voltage-sensitive dye. Between the optic fiber and photodiode in the photodetector, we put a colored glass filter. This filter pass well the fluorescent light of the dye with longer wavelength but it prevent the excitation light with shorter wavelength.We have tested the four voltage-sensitive dyes, RH-414, RH-421, RH-704 and RH-795. The optical signal size of RH-414 was very large but, since this dye has somewhat phototoxic effect and bleached rapidly, it was not fit for our relatively long lasting experiment. We did not find any toxic effect from the preparation stained with other three dyes, but the signal size was small and signal averaging was needed for analyzing the wave shape. We assumed the optical signals also detect the some changes (perhaps due to the volume changes of the preparation) other than the direct membrane potential changes but synchronized to the electrical stimulation.