Activities of lysosomal enzymes in isolated glomeruli. Alterations in experimental nephrosis

To study the role of lysosomal enzymes in glomeruli, we examined specific activities of lysosomal hydrolases in isolated glomeruli and, for comparison in isolated tubules, from rat kidney cortex of normal animals and animals with puromycin aminonucleoside nephrosis (PAN). Nephrotic syndrome was induced in rats by a single intraperitoneal injection of aminonucleoside and the rats were sacrificed at the time of peak proteinuria. Colloidal iron staining of renal cortex demonstrated decreased staining for the epithelial polyanion in animals with PAN. Lysosomal enzymes were determined by fluorogenic and colorimetric methods. In normal kidney, total specific activities of cathepsin beta 1, beta-2-fucosidase, acetyl-beta-glucosaminidase, and arylsulfatase were lower in glomeruli compared with tubules and with tissue slices of the same kidney. Total activity of acid phosphatase was higher in glomeruli than tubules. In glomeruli of PAN rats, there were lower activities of N-acetyl-beta-glucosaminidase, D-fucosidase, beta-glucosidase, beta-glucoronidase, and arylsulfatase compared with control rats. Activity of acid phosphatase, on the other hand, was higher in glomeruli of PAN than control rats. All differences were statistically significant. These studies demonstrate that (1) activities of lysosomal enzymes in normal glomeruli and in glomeruli of nephrotic rats have a property distinct from the rest of the kidney, and (2) the specific activities of lysosomal hydrolases are altered in glomeruli of rats with PAN. These studies suggest that changes in activities of lysosomal enzymes may be related to pathogenesis of this glomerulopathy.