Takashima S
Biophys J. 1979 Apr;26(1):133-42. doi: 10.1016/S0006-3495(79)85240-6.
Since the discovery of Cole and Curtis (1938. Nature (Lond.). 142:209 and 1939. J. Gen. Physiol. 22:649) that the imaginary components, i.e., capacitive and inductive components, of the admittance of squid axon membrane remained unchanged during the action potential, there have been numerous studies on impedance and admittance characteristics of nerves. First of all, it is now known that the dielectric capacitance of the membrane is frequency dependent. Second, the recent observation of gating currents indicates that dipolar molecules may be involved in the onset of ionic currents. Under these circumstances, the author felt it necessary to reinvestigate the membrane admittance characteristics of nerve axons. The measurements by Cole and Curtis were performed mainly at 20 kHz, indicating that their observation was limited only to the passive membrane capacitance. To detect the change in the capacitive component during the action potential, we performed transient admittance measurements at lower frequencies. However, the frequency range of the measurements was restricted because of the short duration of the normal action potential. In addition, a change in the inductive component obscured the low frequency behavior of the capacitance. To use wider frequency range and simplify the system by eliminating the inductive component, the potassium current was blocked by tetraethyl ammonium, and the increase in the capacitive component was reinvestigated during the long action potential. The admittance change under this condition was found to be mostly capacitive, and conductance change was very small. The increase in the capacitive component was from 1.0 to 1.23 muF/cm2.
自科尔和柯蒂斯（1938年，《自然》（伦敦），142:209；1939年，《普通生理学杂志》，22:649）发现枪乌贼轴突膜导纳的虚部，即电容性和电感性分量，在动作电位期间保持不变以来，已经有许多关于神经阻抗和导纳特性的研究。首先，现在已知膜的介电电容与频率有关。其次，最近对门控电流的观察表明，偶极分子可能参与离子电流的起始。在这种情况下，作者认为有必要重新研究神经轴突的膜导纳特性。科尔和柯蒂斯的测量主要在20千赫兹进行，这表明他们的观察仅限于被动膜电容。为了检测动作电位期间电容性分量的变化，我们在较低频率下进行了瞬态导纳测量。然而，由于正常动作电位持续时间短，测量的频率范围受到限制。此外，电感性分量的变化掩盖了电容的低频行为。为了使用更宽的频率范围并通过消除电感性分量来简化系统，用四乙铵阻断钾电流，并在长动作电位期间重新研究电容性分量的增加。发现在这种情况下的导纳变化主要是电容性的，而电导变化非常小。电容性分量的增加从1.0微法/平方厘米到1.23微法/平方厘米。
