Zinc deficiency and the kidney. I. Effect on renal carbonic anhydrase activity

Tissue zinc concentration and the activity of the zinc metalloenzyme, carbonic anhydrase, were quantified in whole blood and kidneys of weanling male Sprague-Dawley rats with diet-induced zinc deficiency. Zinc-deficient rats were fed ad libitum a commercially prepared diet containing less than 1 ppm zinc. Zinc-supplemented rats were ad libitum or pair-fed a control diet containing 60 ppm zinc. All animals were fed their respective diets for 3-6 weeks. Body and kidney growth were severely compromised after 3 and 6 weeks of feeding the zinc-deficient diet. Plasma and kidney zinc concentrations were significantly decreased in zinc-deficient animals after 6 weeks. While whole blood carbonic anhydrase activity of zinc-deficient rats was significantly greater than zinc-supplemented animals after 6 weeks, no differences in renal carbonic anhydrase activity were found between zinc-deficient animals and pair-fed controls. Results reported in this study suggest that zinc deficiency imposed at weaning in rats may be a contributing factor to retarded kidney maturation and alterations in blood carbonic anhydrase activity.