Fishman H M, Moore L E, Poussart D
Biophys J. 1977 Aug;19(2):177-83. doi: 10.1016/S0006-3495(77)85578-1.
The complex admittance of squid (Loligo pealei) axon was measured rapidly (within 1 s) with pseudo-random small signals and discrete Fourier transform techniques under guarded, "space-clamp" conditions and during suppression of ion conduction. Asymmetry currents were measured by paired step clam pulses of +/-70 mV from a holding potential of -97 mV and gave an apparent capacitance of 0.36 muF/cm2. However, the admittance data showed no change in capacitance at holding potentials from -97 to -67 mV and gave a decrease of 0.07 of 0.15 muF/cm2 at -37 mV. The failure to observe a capacitance increase at low membrane potentials suggests the following possibilities: (a) the asymmetry current is a displacement current that inactivates completely with time, and (b) the asymmetry current is not a displacement current and arises from large signal effects (i.e., delayed nonlinearity in ionic current) on the membrane.
在保护的“空间钳制”条件下以及离子传导受抑制期间，利用伪随机小信号和离散傅里叶变换技术，快速（在1秒内）测量了枪乌贼（Loligo pealei）轴突的复导纳。通过从-97 mV的保持电位施加±70 mV的成对阶跃钳制脉冲来测量不对称电流，得出表观电容为0.36 μF/cm²。然而，导纳数据显示，在-97至-67 mV的保持电位下电容没有变化，而在-37 mV时电容从0.15 μF/cm²下降了0.07。在低膜电位下未观察到电容增加，这表明以下几种可能性：（a）不对称电流是一种随时间完全失活的位移电流；（b）不对称电流不是位移电流，而是由膜上的大信号效应（即离子电流中的延迟非线性）引起的。
