Morphological changes in the kidneys of mice with proteinuria induced by albumin-overload.

Female CBA/H-T6T6 mice were given daily i.p. injections of 1 ml of saline containing 250 mg of human serum albumin (HSA) for 7 consecutive days. Control mice received the same volume of saline only. At approximately 24 hourly intervals for the 10 days after the first injection, groups of mice (3 HSA and 1 saline-injected) were killed and kidney tissue was taken for light (LM) scanning (SEM) and transmission (TEM) electron microscopy. Small numbers of glomeruli with Bowman's space filled with protein and fine, radially-disposed casts in collecting tubules were observed by LM. SEM revealed focal changes in both endothelium and epithelium, and in a few cases severely damaged epithelial cells were seen. TEM showed numerous small regions of loss or change in shape of foot processes. Epithelial cell branches became increasingly swollen. By the third day after the last injection glomerular morphology appeared to have returned to normal. Although the cause of the proteinuria was attributed to the effects of HSA-induced increased blood viscosity, the focal distribution of the observed morphological changes remains unexplained.