Borst A, Heck D, Thomann M
Friedrich-Miescher-Laboratory of the Max Planck Society, Tuebingen, Germany.
Neurosci Lett. 1997 Nov 28;238(1-2):29-32. doi: 10.1016/s0304-3940(97)00836-7.
For investigating neuronal information processing at the cellular level, a technique which visualizes the voltage distribution within single neurons in situ would be extremely useful. Voltage-sensitive dyes are, in principle, capable of reporting membrane potential [Cohen, L.B. and Salzberg, B.M., Rev. Physiol. Biochem. Pharmacol., 83 (1978) 35-88; Grinvald, A., Lieke, E.E., Frostig, R.D. and Hildesheim, R., J. Neurosci., 14 (1994) 2545-2568; Kleinfeld, D., Delaney, K.R., Fee, M.S., Flores, J.A., Tank, D.W. and Gelperin, A., J. Neurophysiol., 72 (1994) 1402-1419]. However, their application to single cells internally is technically difficult [Antic, S. and Zecevic, D., J. Neurosci., 15 (1995) 1392-1405; Grinvald, A., Salzberg, B.M., Lev-Ram, V. and Hildesheim, R., Biophys. J., 51 (1987) 643-651; Kogan, A., Ross, W.N., Zecevic, D. and Lasser-Ross, N., Brain Res., 700 (1995) 235-239; Zecevic, D., Nature, 381 (1996) 322-325]. An alternative strategy consists in applying the dye from the outside to all cells in the tissue, while manipulating a single cell by current injection [Krauthamer, V. and Ross, W.N., J. Neurosci., 4 (1984) 673-682; Ross, W.N. and Krauthamer, V., J. Neurosci., 4 (1984) 659-672]. Here, we modify this technique to further enhance spatial at the cost of temporal resolution [Borst, A., Z. Naturforsch., 50 (1995) 435-438]. Applied to rat cerebellar slices we demonstrate that the potential spread in individual Purkinje cells can be imaged up to even fine dendritic branches. The acquired optical signals suggest that steadily hyperpolarized Purkinje cells are electrically compact. When permanently depolarized, the somatic input resistance is significantly diminished, yet the spatial voltage drop along the dendrites remains unchanged. As demonstrated by compartmental modeling, this hints to a concentration of outward rectifying currents at the soma of the cells.
为了在细胞水平研究神经元信息处理过程，一种能够原位可视化单个神经元内电压分布的技术将极为有用。电压敏感染料原则上能够报告膜电位[科恩，L.B.和萨尔茨伯格，B.M.，《生理学、生物化学与药理学评论》，83(1978)35 - 88；格林瓦尔德，A.，利克，E.E.，弗罗斯蒂格，R.D.和希尔德斯海姆，R.，《神经科学杂志》，14(1994)2545 - 2568；克莱因费尔德，D.，德莱尼，K.R.，费，M.S.，弗洛雷斯，J.A.，坦克，D.W.和盖尔佩林，A.，《神经生理学杂志》，72(1994)1402 - 1419]。然而，将它们应用于单个细胞内部在技术上存在困难[安蒂克，S.和泽切维奇，D.，《神经科学杂志》15(1995)1392 - 1405；格林瓦尔德，A.，萨尔茨伯格，B.M.，列夫 - 拉姆V.和希尔德斯海姆，R.，《生物物理学杂志》，51(1987)643 - 651；科根，A.，罗斯，W.N.，泽切维奇，D.和拉塞尔 - 罗斯，N.，《脑研究》700(1995)235 - 239；泽切维奇，D.，《自然》，381(1996)322 - 325]。另一种策略是从外部将染料应用于组织中的所有细胞，同时通过电流注入操纵单个细胞[克劳特哈默，V.和罗斯，W.N.，《神经科学杂志》，4(1984)673 - 682；罗斯，W.N.和克劳特哈默，V.，《神经科学杂志》，4(1984)659 - 672]。在此，我们改进了该技术，以牺牲时间分辨率为代价进一步提高空间分辨率[博斯特，A.，《自然科学》，50(1995)435 - 438]。应用于大鼠小脑切片时，我们证明了单个浦肯野细胞中的电位传播甚至可以成像到精细的树突分支。获得的光信号表明，持续超极化的浦肯野细胞在电方面是紧凑的。当永久去极化时，体细胞输入电阻显著降低，但沿树突的空间电压降保持不变。如通过房室模型所证明的，这暗示了外向整流电流在细胞体处的集中。
