Effects of Metabolic Acidosis on Zinc and Calcium Metabolism in Rats

Abstract
To delineate the potential role of renal acidosis on zinc and calcium metabolism, 24 male Charles River rats, with a mean weight of 154 g, were assigned to four groups of 6 rats each. Three groups of rats were given ammonium chloride for 5 days by stomach tube at dosages of 4, 8, 16 mEq/kg/day, respectively. The control group received the solvent (normal saline) only. The animals were fed a semi-purified diet containing 100 ppm of zinc. The total food intake averaged 18, 16, 17 and 18g/day, respectively, for the control and the three treated groups. On the 4th and 5th day, two 24-hour urinary collections for net acid excretion, zinc and calcium excretions were obtained. The net acid excretion progressively increased from 0.85 ± 0.21 µEq/min/kg in the control rats to maximal values of 10.61 ± 0.87 µEq/min/kg in the acid-loaded rats. The net acid excretion is highly correlated with the urinary calcium excretion (r = 0.95, p < 0.01). However, the acid-loading has no effect on the carcass retention of zinc as documented by isotope studies or urinary zinc excretion.