Study of changes of neuronal membrane functions with aging by tissue culture method

可以精确地研究低渗溶液对培养的分离神经元的形态和电生理功能的影响。从Nomarski光学的视频图片的分析中，可以看到细胞的直径增加，然后在应用低渗溶液后恢复到初始值。胎儿神经元中细胞大小的增加速度快4-5倍。比在成熟的神经元。这种短暂的去极化和电阻下降对应于形态学变化。然而，在细胞膜扩张期间，动作电位的幅度几乎没有变化。由膜扩张引起的膜张力增加可能促进通道的开放，这是合理的。细胞膜扩张也可能增加离子透过膜的渗透性，这可能通过稀释细胞内溶质浓度而使溶胀的细胞体积减小到初始体积。在这种适应之后，培养的神经元是 ...更多信息 用弹性面积压缩模量（EACK）法测定了红细胞膜的弹性。分离的神经元被负压吸入硅化的毛细血管，其直径约为神经元的一半。细胞表面积可以从电视监视器屏幕上吸出的神经元的图片计算出来。分离胎鼠和3月龄小鼠背根神经节神经元，测定其面积压缩模量（K）。成年小鼠神经元的K值为21.3 <plus-minus>± 10.3dyn/cm，约为红细胞的1/10。胎鼠DRG神经元的K值为2.8 <plus-minus>± 0.5dyn/cm。细胞膜弹性随年龄增长而下降。由于神经元细胞膜的功能与细胞内的胞质纤维丝密切相关，因此细胞膜的弹性可能会因纤维丝的断裂而受到影响。当10 μ M细胞松弛素D处理成人培养的神经元，弹性几乎没有改变。然而，当10 μ M秋水仙碱施加到神经元时，K值下降到7.80 dyn/cm。这些结果表明，神经元细胞内的微管可以机械地结合到细胞膜上。这些结果表明，神经元膜随着年龄的增长而变得刚性，这种刚性可能导致轴突再生的能力随着年龄的增长而下降。少

The effects of a hypotonic solution on morphology and electrophysiological functions in cultured dissociated neurons can be precisely studied. From the analysis of video pictures from Nomarski optics, diameters of the cells were seen to increase and then recover to the initial values after the application of a hypotonic solution. The rate of increase of cell size in fetal neurons was 4-5 times faster. than in mature neurons. This transient depolarization and decrease of the resistance corresponded to morphological changes. However, the amplitude of an action potential scarcely changed during the cell membrane expansion. It is plausible that increased membrane tension caused by the membrane expansion might facilitate the opening of the channel. The cell membrane expansion might also increase ionic permeability through the membrane.This may reduce a swollen cell volume to the initial one by diluting the intracellular solute concentration. After this adaptation the cultured neurons were a … More ble to survive for a long time and extend process in the hypotonic environment.Cell membrane elasticity has been measured in erythrocytes by the method of Elastic Area Compressibility Modulus(EACK). A dissociated neuron is aspirated by a negative pressure into a siliconized capillary, the diameter of which is about a half that of the neuron. Cell surface area can be calculated from pictures of the aspirated neuron on a TV monitor screen. Dorsal root ganglion neurons from fetal and 3-month-old mice were dissociated and their values of the area compressibility modulus (K) were measured. The K value of adult mouse neurons was 21.3<plus-minus>10.3 dyn/cm which is about 1/10 that of erythrocytes. The K value of fetal mouse DRG neurons was 2.8<plus-minus>0.5 dyn/cm. The cell membrane elasticity decreases with aging. Since neuronal cell membrane functions closely relate to intracellular cytoskeltal filaments, elasticity of the membrane may be affected by disruption of the filaments. When 10 muM cytochalasin D was treated to adult cultured neurons, the elasticity scarcely changed. However, when 10 muM colchicine was applied to the neurons, the K value decreased to 7.80 dyn/cm. This result suggests that intracellular microtubules in a neuron may mechanically bind to the cell membrThese results suggest that a neuronal membrane becomes rigid with aging and this rigidity might cause a capability of neurite regeneration to decrease with aging. Less