Glomerular basement membrane as a compressible ultrafilter.

The ultrafiltration properties of isolated glomerular basement membrane were studied in vitro by forming membrane fragments into thin films for use as ultrafiltration membranes. The filtration properties of the films were examined using cytochrome c, myoglobin, lysozyme, ovalbumin, lactoglobulin, and serum albumin. The films behaved as compressible filters showing size-dependent rejection of the proteins. The behavior of the films was modelled using the fiber matrix hypothesis which gave good prediction of film behavior. The membrane behaved as a random fiber matrix composed of fibers of 0.8-1.0 nm in radius.