Permeability of artificial membranes to a pluridisperse solution of 125I-polyvinylpyrrolidone.

The validity of the transport equation for uncharged macromolecules across a porous membrane developed by Verniory et al. (1973, J. Gen. Physiol. 62:489) has been tested on several types of artificial membranes (Amicon PM-30, XM-50, and XM-100 Diaflo ultrafilters) using a pluridisperse solution of polyvinylpyrrolidone as filtrand. The influence of the filtration pressure on the shape of the sieving curve predicted by the theory has been verified. A mean pore radius and the width of the pore demonstrated that the method used previously to determine the effective filtration pressure in the glomerulus from sieving data is valid. The transport equation previously proposed by Renkin (1954, J. Gen. Physiol. 38:225) gives results that are less consistent than those obtained with the new transport equation.