THE ADMITTANCE OF THE SQUID GIANT-AXON AT RADIO FREQUENCIES AND ITS RELATION TO MEMBRANE-STRUCTURE
THE ADMITTANCE OF THE SQUID GIANT-AXON AT RADIO FREQUENCIES AND ITS RELATION TO MEMBRANE-STRUCTURE
复制标题
DOI：
10.1113/jphysiol.1985.sp015617
复制
发表时间：
1985-01-01
影响因子：
5.5
通讯作者：
URBAN, BW
中科院分区：
文献类型：
--
作者：
HAYDON, DA;URBAN, BW
鱿鱼巨轴突膜的导纳测量使用细胞内电极，在频率高达40 MHz。先前用细胞外电极（科尔，1976）检测到并归因于许旺细胞层的射频分散的存在得到证实，并随后达到更高的频率。对于可比较的分析方法，计算了与科尔（1976）给出的参数相似的膜参数。射频色散的中心频率为aptx。1.8 MHZ以及28 nF cm-2容量和3.3 Ω电容的并联组合的特性。cm 2电阻。当计算轴突膜容量时，考虑到射频色散，该容量在整个研究范围内保持频率依赖性。如果它是假设，在高频率的轴膜容量成为恒定的值约为脂双层，无线电频率色散被发现，这不能占在一个简单的等效电路与2个无源组件，但出现从一个网络与弛豫时间的分布。这一结果可能与雪旺细胞层的形态学一致。射频色散可以通过具有中心频率分别为250 kHz和3.2 MHz的2个色散的电路来合理地描述。相应的轴膜容量（100-500 kHz）将是0-6μ F cm-2。在50和100 kHz之间，由膜区域的非极性区域产生的几何容量是轴突膜容量的主要贡献者，并且在该频率范围内最好地监测由脂质双层中的组成变化产生的容量变化。
The admittance of the squid giant axon membrane was measured using an intracellular electrode, at frequencies up to 40 MHz. The existence of a radio frequency dispersion, previously detected with extracellular electrodes (Cole, 1976) and attribued to the Schwann cell layer, was confirmed and followed to higher frequencies. For a comparable method of analysis, membrane parameters similar to those given by Cole (1976) were calculated. The radio frequency dispersion has a center frequency at .apprx. 1.8 MHZ and the properties of a parallel combination of a 28 nF cm-2 capacity and a 3.3 .OMEGA. cm2 resistance. When the axon membrane capacity is calculated, taking into account the radio frequency dispersion, the capacity remains frequency dependent throughout the range studied. If it is assumed that at high frequencies the axolemma capacity becomes constant at approximately the value for a lipid bilayer, a radio freuqency dispersion is found which cannot be accounted for in terms of a simple equivalent circuit with 2 passive components, but appears to arise from a network with a distribution of relaxation times. This result could be consistent with the morphology of the Schwann cell layer. The radio frequency dispersion can be described reasonably well by a circuit with 2 dispersions having center frequencies of 250 kHz and 3.2 MHz respectively. The corresponding axolemma capacity (100-500 kHz) would be .apprx. 0-6 .mu.F cm-2. Between 50 and 100 kHz the geometrical capacity arising from the non-polar regions of the regions of the membrane is a major contributor to the axon membrane capacity and capacity variations arising from compositional changes in the lipid bilayer are best monitored in this frequency range.