Glomerular Albumin Leakage and Morphology after Neutralization of Polyanions. I.

Abstract

In order to decide whether foot process abnormalities in nephrotic states are the cause or the consequence of proteinuria, the polycation protamine has been applied to isolated perfused rat kidneys and functional parameters and morphology have been compared. With 110 μg/ml protamine the albumin clearance ratio increased from 2.0 + 0.7 × 10^-3 in controls to 14.8 + 6.9 × 10^-3 10-20 min after application and even to 98.0 + 30.8 × 10^-3 after 50-80 min. Micropuncture samples collected from early proximal tubules with pressure control were used to calculate the sieving coefficient which correlated with albumin clearance ratios (controls: 1.8 +1.0 × 10^-3; after 10-20min: 11.8 ± 6.4 × 10^-3; after 50-80 min: 52.0 + 8.5 × 10^-3). Glomerular filtration rate decreased in the early beginning from 1.1 ± 0.2 ml x min^-1 ×g^-1 kidney to 0.7+ 0.2 ml × min^-1 ×g^-1 kidney, but remained constant throughout the whole experiment. Despite the markedly increased albuminuria there were no changes in glomerular foot process morphology with the protamine dose used.

A monoclonal antibody against GBM heparan sulfate induces an acute selective proteinuria in rats

“…Moreover, enzymatic removal of HS from the glomerular capillary wall increases the passage of native ferritin and albumin into the urinary space [10,11]. These data were corroborated by inves-© 1992 by the International Society of Neplirology injection of cationic molecules, GBM permeability increased due to the neutralization of HS-associated anionic sites of the glomerular capillary wall [12][13][14][15][16]. However, the significance of HS for the permselectivity of the GBM and for the induction of proteinuria is still not completely understood, and a number of controversies still exist [17-201. To study the impact of HS for the permselective properties of the GBM in more detail, antibodies against HS can be an important tool.…”

Spatial composition and turnover of the main molecules in the adult glomerular basement membrane

“…2 Without wading into this debate, it has been previously proposed that the anionic charge within the GBM contributes to albumin exclusion. [3][4][5][6][7][8][9][10][11] Whether or not this is the case, just to better assess the evidence upon which this assertion is based, would likely be aided by improved estimates of the distribution of all ECM contributions to anionic charge within the GBM. In this review, we will restrict ourselves to the main GBM molecules and leave estimates of the GBM anionic distribution for a future study.…”