HISTOLOGICAL AND SUBCELLULAR-DISTRIBUTION OF 65 AND 70 KD HEAT-SHOCK PROTEINS IN EXPERIMENTAL NEPHROTOXIC INJURY

The cellular distribution of 65 and 70 kD heat shock proteins (HSPs) w as studied in the normal rat kidney and after acute tubular necrosis ( ATN) induced by inorganic mercury (HgCl2). In the normal kidney the 65 kD HSP was found in the cytoplasm of podocytes and proximal convolute d tubules, whereas the 70 kD HSP was located in nuclei and cytoplasm o f podocytes, cortical convoluted, and collecting tubules. The distribu tion of both HSPs along ATN changed as a function of time. In the earl y phase, before evidence of histological damage, both HSPs were found in the pielocalyceal epithelium and medullary collecting tubules. Duri ng the necrotic phase, HSPs coexisted with sites of severe damage (i.e . cortical tubules). With immunoelectron microscopy, damaged cells sho wed an abundance of 65 kD HSP-I in mitochondria, as well as in chromat in and nucleoli, while 70 kD HSP-I was overexpressed in the cytoplasm, mitochondria, lysosomes, cytoskeleton, chromatin, and nucleoli, and c oincided with urinary excretion of HSPs. In the postregenerative phase , the distribution of HSPs was similar to that found in the normal kid ney. HSPs of 65 and 70 kD were encountered constitutionally and their immunolabeling is correlated with the magnitude of cell injury.