TRANSPORT OF INORGANIC-PHOSPHATE IN RENAL CORTICAL BRUSH-BORDER MEMBRANE-VESICLES OF CADMIUM-INTOXICATED RATS

The effect of cadmium intoxication on the renal proximal tubular phosphate transport system was studied in adult male Sprague-Dawley rats. Subcutaneous injections of CdCl2 at a dose of 2 mg Cd/kg body wt per day for 2 weeks induced marked polyuria, glycosuria, proteinuria, and phosphaturia, which are characteristics of chronic cadmium intoxication, In the renal cortical brush-border membrane vesicles prepared from cadmium-intoxicated rats, the cadmium content was drastically increased and the Na+-dependent phosphate uptake was markedly attenuated. Similar results were obtained in normal membrane vesicles directly exposed to free cadmium, These results indicate that cadmium intoxication impairs the Na+-phosphate cotransport system in the proximal tubular brush-border membrane, which may lead to phosphaturia in intact animals. (C) 1995 Academic Press, Inc.