Glomerular protein filtration in normal and nephritic rats. A micropuncture study.

The acute heterologous phase of anti-basement membrane glomerulonephritis in rats was studied morphologically and functionally at the single nephron level. In samples drawn from Bowman's space or from the very early segment of the proximal tubule the protein content was measured by ultra micro-disc-electrophoresis. Morphologically, in rats which were treated with anti-glomerular basement-membrane serum (AGBM) no significant changes could be seen in light microscopy whereas in immunohistology the typical, linear, subendothelial fluorescent staining for IgG could be seen. In controls, small amounts of albumin were filtered (7.57 +/- 0.66 mug/min X 100 g body weight, n = 14) but in nephritic animals the filtered load of albumin increased significantly to 58.33 +/- 4.10 mug/min X 100 g body weight, (n = 8). Besides this increased albumin filtration also several serum globulins could be detected, whereas in controls they were missing. Total GFR and proximal passage time did not change significantly. It is concluded that the glomerulus is an effective barrier for protein under control conditions and that it becomes permeable for albumin and higher molecular weight serum proteins following the antigen antibody reaction at the glomerular basement membrane in the AGBM-treated animals.