Longuet-Higgins H C, Austin G
Biophys J. 1966 Mar;6(2):217-24. doi: 10.1016/S0006-3495(66)86652-3.
This paper presents a theoretical analysis of the kinetics of osmotic transport across a semipermeable membrane. There is a thermodynamic connection between the rate of flow under a hydrostatic pressure difference and the rate of flow due to a difference in solute concentration on the two sides. One might therefore attempt to calculate the osmotic transport coefficient by applying Poiseuille's equation to the flow produced by a difference in hydrostatic pressure. Such a procedure is, however, inappropriate if the pores in the membrane are too small to allow molecules to "overtake." It then becomes necessary to perform a statistical calculation of the transport coefficient, and such a calculation is described in this paper. The resulting expression for the number of solvent molecules passing through a pore per second is J = m D(1) deltan(1)/l(2) where m is the number of solvent molecules in the pore, l is the length of the pore, D(1) is the self-diffusion coefficient of the solute, and deltan(1) the difference in solvent mole fraction on the two sides of the membrane. This equation is used for estimating the number of pores per unit area of the squid axon membrane; the result is 6 x 10(9) pores/cm(2).
本文对跨半透膜渗透运输的动力学进行了理论分析。在静水压差作用下的流速与两侧溶质浓度差异导致的流速之间存在热力学联系。因此，人们可能会尝试通过将泊肃叶方程应用于由静水压差产生的流动来计算渗透运输系数。然而，如果膜中的孔隙太小以至于分子无法“超车”，那么这样的做法是不合适的。此时就有必要对运输系数进行统计计算，本文将描述这样的计算。所得的每秒通过一个孔隙的溶剂分子数的表达式为(J = m D(1) deltan(1)/l(2))，其中(m)是孔隙中溶剂分子的数量，(l)是孔隙的长度，(D(1))是溶质的自扩散系数，(deltan(1))是膜两侧溶剂摩尔分数的差异。该方程用于估计鱿鱼轴突膜单位面积的孔隙数量；结果是(6×10(9))个孔隙/平方厘米。
