Takashima S
J Membr Biol. 1976 Jun 9;27(1-2):21-39. doi: 10.1007/BF01869127.
The change in membrane capacitance and conductance of squid giant axons during hyper- and depolarizations was investigated. The measurements of capacitance and conductance were performed using an admittance bridge with resting, hyperpolarizaed and depolarized membranes. The duration of DC pulses is 20-40 msec and is long enough to permit the admittance measurements between 1 and 50 kHZ. The amplitudes of DC pulses were varied between 0 and 40 mV for both depolarization and hyperpolarization. Within these limited experimental conditions, we found a substantial increase in membrane capacitance with depolarization and a decrease with hyperpolarization. Our results indicate that the change in membrane capacitance will increase further if low frequencies are used with larger depolarizing pulses. The change in membrane capacitance is frequency dependent and it increases with decreasing frequencies. The analyses based on an equivalent circuit (vide infra) gives rise to a time constant of active membrane capacitance close to that of sodium currents. This result indicates that the observed capacitance changes may arise from sodium channels. A brief discussion is given on the nature of frequency-dependent membrane capacitance of nerve axons.
研究了枪乌贼巨大轴突在超极化和去极化过程中膜电容和电导的变化。使用导纳电桥对静息、超极化和去极化膜进行电容和电导测量。直流脉冲持续时间为20 - 40毫秒，足够长以允许在1至50千赫兹之间进行导纳测量。去极化和超极化时直流脉冲幅度在0至40毫伏之间变化。在这些有限的实验条件下，我们发现去极化时膜电容大幅增加，超极化时膜电容减小。我们的结果表明，如果使用低频和更大的去极化脉冲，膜电容的变化将进一步增加。膜电容的变化与频率有关，且随频率降低而增加。基于等效电路（见下文）的分析得出活性膜电容的时间常数接近钠电流的时间常数。这一结果表明，观察到的电容变化可能源于钠通道。文中对神经轴突频率依赖性膜电容的性质进行了简要讨论。
