FUNCTION OF THE KIDNEYS UNDER CONDITIONS OF EXPERIMENTAL OXALATE NEPHROLITHIASIS

Abstract

THE AIM of the investigation was to study kidney functions in rats under conditions of experimental oxalate nephrolithiasis. MATERIAL AND METHODS. Male Wistar rats were given drinking water with 1% solution of ethylene glycol during 3 weeks. The concentration of oxalate, calcium and phosphorus was determined in daily urine. Activity of marker enzymes lactate dehydrogenase (LDG), γ-glutamil transferase (GGT) and N-acetyl-β-D-glucosaminidase (NAG) was also determined. The presence of calcium-positive deposits on kidney slices was determined by the Koss histological method. RESULTS. Daily using ethylene glycol by rats was followed by the development of hyperoxaluria, which was due to increased formation of oxalate ions in the liver and appearance of oxalate supersaturation in tubule urine. In the experiments it was shown that enzymatic activation of urine against the background of ethylene glycol was substantially increased. Activity of NAG became 20 times higher, GGT – 3.7 times higher. LDG activity which had become 7.5 times higher by the end of the first week, then gradually returned to the initial level. These changes are evidence of injuries to the tubule cell membranes, followed by cytolysis and of pronounced impairment of the renal tubule function. Morphological investigation of kidney slices has detected numerous calcium-positive deposits localized mainly on the renal papilla surface. CONCLUSION. Experiments with continuous intake by rats of ethylene glycol have given an irrefutable proof of progression of calcium-oxalate nephrolithiasis. It points to the developed hyperoxaluria, fermenturia and the presence of calcium positive inclusions on the renal papilla surface. The above changes are signs of experimental urolithiasis in rats.