MULLINS L J
J Gen Physiol. 1959 May 20;42(5):1013-35. doi: 10.1085/jgp.42.5.1013.
The membrane of the squid axon is considered on the basis of a pore model in which the distribution of the pore sizes strongly favors K(+) transfer when there is no potential. Electrical asymmetry causes non-penetrating ions on the membrane capacitor to exert a mechanical force on both membrane surfaces and this force results in a deformation of the membrane pore system such that it assumes a distribution of sizes favoring the ions exerting mechanical force. The ions involved appear to be Ca(++) on the outside of the membrane and isethionate(-), (i(-)) on the inside; as Ca(++) is equivalent in size to Na(+), the charged membrane is potentially able to transfer Na(+), when the ions deforming the membrane pore distribution are removed. A depolarization of the membrane leads to an opening of pores that will allow Na(+) penetration and a release of the membrane from deformation. The pores revert to the zero-potential pore size distribution hence the Na permeability change is a transient. Calculation shows that the potassium conductance vs. displacement of membrane potential curve for the squid axon and the "inactivation" function, h, can be obtained directly from the assumed membrane distortion without the introduction of arbitrary parameters. The sodium conductance, because it is a transient, requires assumptions about the time constants with which ions unblock pores at the outside and the inside of the membrane.
基于一种孔隙模型来考虑鱿鱼轴突的膜，在该模型中，当不存在电位时，孔隙大小的分布强烈有利于K(+)的转移。电不对称性导致膜电容上的非穿透性离子在膜的两个表面上施加机械力，并且该力导致膜孔隙系统的变形，使得其呈现出有利于施加机械力的离子的大小分布。所涉及的离子似乎在膜的外部是Ca(++)，在内部是羟乙磺酸盐(-)，(i(-))；由于Ca(++)在大小上与Na(+)相当，当使膜孔隙分布变形的离子被去除时，带电的膜有可能能够转移Na(+)。膜的去极化导致孔隙开放，这将允许Na(+)渗透并使膜从变形中释放出来。孔隙恢复到零电位孔隙大小分布，因此Na渗透性变化是短暂的。计算表明，鱿鱼轴突的钾电导与膜电位位移曲线以及“失活”函数h可以直接从假定的膜变形中获得，而无需引入任意参数。钠电导由于是短暂的，需要对离子在膜外部和内部使孔隙解除阻塞的时间常数进行假设。
