Keynes R D, Bezanilla F, Taylor R E, Rojas E
Philos Trans R Soc Lond B Biol Sci. 1975 Jun 10;270(908):365-75. doi: 10.1098/rstb.1975.0016.
When tetrodotoxin is applied to or washed away from the squid giant axon, the rates at which the sodium conductatnce is blocked and unblocked are an order of magnitude smaller than those reported for the isolated node of Ranvier. This slowing is to be expected if in squid the tetrodotoxin binding sites act as a saturable sink in series with the barrier to free diffusion imposed by the presence of the Schwann cell. A comparison has been made between the rates observed experimentally and those calculated for a computer model of the system, in order to estimate the apparent density in the membrane of both specific and non-specific tetrodotoxin binding sites. The figure thus obtained for the number of sodium channels in the squid giant axon, several hundred per square micrometre, agrees well with those derived from other lines of argument.
当将河豚毒素施加于鱿鱼巨轴突或从其冲洗掉时，钠电导被阻断和解除阻断的速率比在分离的郎飞结处报道的速率小一个数量级。如果在鱿鱼中河豚毒素结合位点充当与施万细胞存在所施加的自由扩散屏障串联的可饱和汇，那么这种减慢是可以预期的。为了估计膜中特异性和非特异性河豚毒素结合位点的表观密度，已对实验观察到的速率与针对该系统的计算机模型计算出的速率进行了比较。由此获得的鱿鱼巨轴突中钠通道数量的数字，即每平方微米数百个，与从其他论证得出的数字非常吻合。
