Effectiveness of a traditional Chinese medicine, Wulingsan, in suppressing the development of nephrocalcinosis induced by a high phosphorus diet in young rats.

The development of nephrocalcinosis in rats fed a high phosphorus diet, and the effectiveness of the Chinese traditional medicine, Wulingsan, and its components (Poria, Alismatis Rhizoma, Atractylodis Rhizoma, Cinnamomi Ramus, Polyporus) in suppressing the development of calcinosis were studied. The rats were fed a high phosphorus diet (1.5% P) supplemented with Wulingsan or its individual components (0.5 g/kg body weight) as separate experimental groups for a 2-week period. Upon histological observation by light microscopy and electron microscopy, signs of nephrocalcinosis were observed in almost all areas of the kidney. Calculi, consisting mainly of needle-shaped crystals of hydroxyapatite, were observed in the proximal tubules, in the collecting ductal lumina, and in the mitochondria of the proximal tubular cells and the interstitial cells. X-ray microanalysis revealed that the calculi were composed of hydroxyapatite (Ca and P). In the group fed the diet supplemented with Wulingsan, the severity of calcinosis in the corticomedullary junction was only slight. In all groups fed individual components of Wulingsan, the severity of calcinosis was almost the same as that in the group fed the high phosphorus diet (1.5% P). Wulingsan suppressed the development of calcinosis in rats fed the high phosphorus diet supplemented with this Chinese medicine, whereas its individual components alone had no effect. The process of calcinosis and the mechanism responsible for the activity of this Chinese medicine in the suppression of calcinosis are discussed.