IMPROVEMENT EFFECT OF SWITCHING TO A DIET OF LOWER PHOSPHORUS-CONTENTIN RATS WITH HIGH PHOSPHORUS DIET-INDUCED NEPHROCALCINOSIS AND DEPRESSION OF PROXIMAL TUBULAR FUNCTION

The purpose of this study was to reveal the improvement effect of swit ching to a diet of lower phosphorus content on high phosphorus diet-in duced nephrocalcinosis and depression of proximal tubular function. Th e rats were fed a purified diet containing 0.5% phosphorus as the cont rol diet (control group) and 1.5% phosphorus as the high phosphorus di et (damage group) for 14 days. The. damage group displayed nephrocalci nosis and depression of proximal tubular function. Subsequently, the r ats in the damage group were switched from the high phosphorus diet to the control diet (improvement group) for 21 days. Degree of nephrocal cinosis was reduced in the improvement group compared with the damage group, especially, the improvement group was reduced deposition of cal cium in the cortex and in the medulla. As indicators of proximal tubul ar function, N-acetyl-beta-D-glucosaminidase activity in the urine and urinary beta(2)-microglobulin excretion were significantly lower in t he improvement group than in the damage group. We conclude that the ne phrocalcinosis and depression of proximal tubular function induced by a high phosphorus diet are improved by switching to a diet of lower ph osphorus content. (C) 1998 Elsevier Science.