Lysosomale Enzyme in der Niere des Hundes bei chronischer interstitieller Nephritis und Tubulonephrose

Abstract

Introduction: Lysosomal enzymes have frequently been demonstrated in the kidneys of small laboratory animals by histochemical methods. Such methods, however, were rarely applied to canine kidneys. The present paper reports some histochemical investigations on the localization and discharge of lysosomal enzymes in canine kidneys with special regard to chronic interstitial nephritis. Material and Methods: The enzyme-histochemical study is based on fresh kidney samples from 50 dogs. Enzymes studied were acid phosphatase, β-glucuronidase and N-acetyl-β-glucosaminidase. Cryostat sections of kidneys prefixed in formol-calcium chloride as well as unfixed and freeze-dried cryostat sections according to Winckler (1970 a, b, c) were used. Results: Normal, nephritic and nephrotic canine kidneys were examined with regard to enzyme localization and activity. In cases of chronic interstitial nephritis an enlargement of lysosomes in tubular epithelial cells was observed in areas of peritubular fibrosis. The lysosomal structures may coalesce to large irregular masses in the course of the nephritis. In predominantly degenerative lesions of the tubular epithelium the lysosomes undergo similar changes. Furthermore, a decrease of enzyme activities and defecation of lysosomal structures were demonstrated. In these cases extracellular enzymatic reaction products were found in the lumina of renal tubules and vessels. Discussion: On the basis of these findings it appears that after the intratubular liberation of lysosomal enzymes a reabsorption into the peritubular veins of the renal medulla may be possible. The normal and diseased canine kidney could be a suitable model for studies on lysosomes.