Steady state material transfer through biological barriers

¹ Biology Department, Brookhaven National Laboratory, Upton, New York

A general theory of material transfer through biological barriers, based on the idea that diffusion processes obey Newton's laws of motion, is outlined. The distribution of permeant ions in the system phase , barrier, phase ß, when the system is in a stationary state, is discussed. The theory predicts that the logarithms of the concentration ratios of ion pairs in the two phases should be nearly proportional to the flow of water through the barrier when stationary states of the first order due to steady flows of water are established. The theory further predicts that, given similar conditions, the ratio of the logarithms of the concentration ratios of two ion pairs in systems containing two or more salts should be approximately equal to the inverse ratio of the diffusion coefficients of the respective salts in water and hence quasi-invariant.