Permselectivity: relation between foot process simplification and macromolecular configuration.

The simplification of the foot processes of the glomerular epithelial cells is the structural hallmark of proteinuria in nephrotic man and animals. The increased shear force in a filtrate funnelled within the lamina densa to simplified slit pores may decrease the friction of macromolecules which are prolate ellipsoids (cigar-shaped). The permeability of rigid long narrow proteins such as albumin, transferrin and immunoglobulin G may selectively increase when the slit pore is converted from a wide serpentine to a straight narrow space.