Konnerth A, Orkand P M, Orkand R K
Max-Planck-Institute of Biophysical Chemistry, Gottingen-Nikolausberg, Federal Republic of Germany.
Glia. 1988;1(3):225-32. doi: 10.1002/glia.440010308.
Voltage-sensitive dyes were used to study the changes in membrane potential in axons and glial cells of the frog optic nerve following electrical stimulation. The lack of a signal in the unstained nerve and the multiphasic action spectra after staining indicated that the optical responses were from the extrinsic dyes. Changes in dye absorption and fluorescence had rapid and slow phases. The rapid phases resulted from action potentials in myelinated and unmyelinated axons. The kinetics of the slow phase of the optical response were similar to the depolarization recorded from the glial cells with intracellular electrodes. The ratio of the amplitudes of the fast and slow phases was characteristic for each type of dye. Pharmacological analysis of the action potential of the unmyelinated axons revealed tetrodotoxin-sensitive sodium channels and 4-aminopyridine-sensitive potassium channels. Repeated exposure of the stained preparation to light led to photodynamic damage as shown by a block of recovery of the glial depolarization. An electron microscopic morphometric study of the nerve was carried out in an effort to understand the contribution of the various anatomical elements to the compound optical response. The ratio of unmyelinated axon membrane to glial membrane was much greater than was the ratio of the fast and slow components of the signal, suggesting that the dyes either had a higher affinity for glial membrane or did not penetrate the nerve uniformly.
使用电压敏感染料研究电刺激后青蛙视神经轴突和神经胶质细胞膜电位的变化。未染色神经中缺乏信号以及染色后的多相作用光谱表明，光学反应来自外在染料。染料吸收和荧光的变化有快速和缓慢阶段。快速阶段是由有髓鞘和无髓鞘轴突中的动作电位引起的。光学反应缓慢阶段的动力学与用细胞内电极从神经胶质细胞记录的去极化相似。每种染料的快速和缓慢阶段振幅之比是其特征。对无髓鞘轴突动作电位的药理学分析揭示了对河豚毒素敏感的钠通道和对4-氨基吡啶敏感的钾通道。如神经胶质去极化恢复受阻所示，将染色制剂反复暴露于光下会导致光动力损伤。对神经进行了电子显微镜形态计量学研究，以了解各种解剖成分对复合光学反应的贡献。无髓鞘轴突膜与神经胶质膜的比例远大于信号快速和缓慢成分的比例，这表明染料要么对神经胶质膜具有更高的亲和力，要么没有均匀地穿透神经。
