A step forward in understanding glomerular filtration

The mechanism underlying glomerular filtration barrier selectivity has not been resolved. A new study that reports an inverse correlation between slit diaphragm density and proteinuria in a genetic mouse model of focal segmental glomerulosclerosis suggests that podocytes function to compress the glomerular basement membrane (GBM) and that failure of this process results in GBM stretching and increased permeability.