Immunohistochemical Analyses of Serum Proteins in Puromycin Aminonucleoside Nephropathy of Living Rat Kidneys

In vivo cryotechnique (IVCT) has been useful to examine native immunolocalizations of soluble proteins in animal kidneys, reflecting their living states. By using them, we have examined some immunolocalized proteins in nephronsof rat kidneys under experimental nephropathy induced by puromycinaminonucleoside (PAN) administration. At day 3 or day 9 after intraperitoneal PAN injection, IVCT was routinely performed for kidneys of anesthetized rats and followed by freeze-substitution fixation. Serial tissue sections were first stained with hematoxylin-eosin (HE) and then immunostained for serum albumin and IgG1. The excretion of urinary proteins began to increase at day 3. Plasma protein analyses indicated the typical nephrosis. At day 3, although little morphological changes were detected by HE staining, both albumin and IgG1 were immunolocalized along cytoplasm of podocytesand in apical parts of epithelial cells of proximal convoluted tubules. At day 9, intravascular congestion of erythrocytes was observed in almost all of the glomerular basement membranes(GBMs). Their relative immunoreactivities of albumin and IgG1 were weaker within blood vessels including GBMs. IVCT revealed dynamically changing processes of protein excretion and reabsorption in various segments of nephrons.