Transfer impedances between different regions of branched excitable cells.
Transfer impedances between different regions of branched excitable cells.
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DOI：
10.1152/jn.1988.59.3.689
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发表时间：
1988-03
影响因子：
2.5
通讯作者：
L. Moore;K. Yoshii;B. Christensen
中科院分区：
文献类型：
--
作者：
L. Moore;K. Yoshii;B. Christensen
1. 采用电压箝位和频域技术相结合的方法测量了分支细胞的可兴奋性。采用简化索模型拟合NG-108细胞胞体和生长锥在不同膜电位下的点阻抗函数，建立动力学参数。2. 用形态学确定的模型测量和模拟了体细胞和生长锥之间的传递阻抗函数。在这些实验中，膜电位由单电极电压钳控制，从而允许对任何任意输入的传递函数进行估计，例如单个突触电流用于不同程度的张力突触驱动。在此基础上，基于单个细胞上不同位置之间的传递函数，对不同区域输入的积分进行了评估。3. 外部稳态电流的激活导致共振阻抗函数，用于评估分支可兴奋细胞不同区域的离子通道的动力学特性。对于简单的分支模式，点阻抗和转移阻抗显示活跃生长锥的共振频率比活跃体细胞低。4. 更复杂的分支模式显示了意想不到的结果，即生长锥记录的电压依赖共振频率高于体细胞记录。当生长锥被激活时，较高的共振频率的存在并不需要更快速的活性钾电导动力学，因为活性电导的时间常数在生长锥和体细胞膜中可以是相同的。5. 综上所述，谐振频率以及阻抗函数的所有其他方面都是详细分支模式和有源电导的复杂相互作用。一般来说，这些相互作用是无法通过被动电紧张分析预测的，特别是当电压相关的电导分布在整个树突树中时。
1. The excitable properties of branched cells were measured using a combination of voltage-clamp and frequency-domain techniques. Point impedance functions from either the soma or growth cone of NG-108 cells were curve fitted with a reduced cable model at different membrane potentials to establish kinetic parameters. 2. Transfer impedance functions between the soma and growth cone were measured and simulated with a morphologically determined model. In these experiments the membrane potential was controlled by a single-electrode voltage clamp thus allowing an estimate of transfer functions for any arbitrary input, such as a single synaptic current for differing degrees of tonic synaptic drive. Furthermore, the integration of different regional inputs was evaluated based on the transfer functions between different locations on an individual cell. 3. The activation of an outward steady-state current leads to resonating impedance functions that were used to evaluate the kinetic properties of ionic channels in different regions of branched excitable cells. For simple branching patterns the point and transfer impedances show lower resonant frequencies for active growth cones compared with active somas. 4. More complex branching patterns showed the unexpected result that the voltage-dependent resonant frequency was higher for the growth cone recording than the soma. The presence of a higher resonant frequency when the growth cone is activated does not require more rapid kinetics of the active potassium conductance, since the time constant of the active conductance can be the same in the growth cone and the soma membrane. 5. In conclusion, the resonant frequencies, as well as all other aspects of the impedance functions, are complicated interactions of the detailed branching patterns and active conductances. In general, these interactions are not predictable from a passive electrotonic analysis, especially when the voltage-dependent conductances are distributed throughout the dendritic tree.