Administration of PAN to rats decreases the fractional clearance of 20 to 38 Å neutral macromolecules, possibly due to a reduction the surface area of glomerular capillaries. The mechanism for the reduction in surface area, however, remains unknown. Also, it is controversial whether the permeability of glomerular filtration barrier remains normal or increases in this experimental disease. Glomerular capillary filtration surface area could decrease as a result of a reduction in size or density or both of endothelial fenestrae. To study this possibility, glomerular morphology was examined by scanning and transmission microscopy in PAN-treated and control rats. Fractional clearances of [125I]PVP were obtained in these rats. Scanning electron microscopy revealed a nonuniform but marked reduction in density and size of endothelial fenestrae in PAN rats. Fractional clearances of 20, 24, 28, 32, 36, 40 and 44 Å PVPs were 0.8980, 0.7652, 0.5490, 0.3581, 0.2216, 0.1233 and 0.0563, respectively. Compared to normals, in PAN rats the fractional clearances for 20 to 32 Å PVPs were lower and for 40 and 44 Å were higher. These findings suggest that in PAN-treated rats, glomerular capillaries undergo two changes. (1) Capillary surface area is reduced due to the endothelial changes, and (2) the upper limit of permeability of glomerular filtration barrier for neutral macromolecules is increased. It is suggested that the glomerular ultrafiltration coefficient is reduced in this disease due to the changes in endothelial cells.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Laboratory and Clinical Medicine|
|State||Published - Dec 1 1979|
ASJC Scopus subject areas
- Pathology and Forensic Medicine