Zinc protects renal function during cadmium intoxication in the rat

Zinc protects renal function during cadmium intoxication in the rat. Am J Physiol Renal Physiol 290: F127-F137, 2006. First published June 7, 2005; doi:10.1152/ajprenal.00366.2004.- This study investigates the effect in the rat of chronic CdCl2 intoxication (500 mu g Cd2+/kg, daily ip injection for 5 days) on renal function and the changes in tight junction proteins claudin-2, claudin-3, and claudin-5 present in rat kidney. We also studied the effect of coadministration of ZnCl2 (500 mu g Zn2+/ kg) during chronic CdCl2 intoxication. Our results indicate that 1) most of the filtered Cd2+ is reabsorbed within the kidney; 2) chronic Cd2+ intoxication can induce a change in renal handling of ions without altering glomerular filtration rate; 3) a delayed nephropathy, showing Fanconi-like features, appears more than 5 days after the end of CdCl2 exposure; 4) epithelial integrity is altered by chronic Cd2+ intoxication affecting the expression and localization of claudin tight junction proteins; and 5) cotreatment with Zn2+ protects against the renal toxic effects of Cd2+, preventing altered claudin expression and inhibiting apoptosis. In conclusion, these results show that Cd2+ toxicity and cellular toxic mechanisms are complex, probably affecting both membrane transporters and tight junction proteins. Finally, Zn2+ supplementation may provide a basis for future treatments.