Influence of cadmium on the intestinal uptake and absorption of calcium in the rat.

To determine the effects of cadmium on the intestinal absorption of calcium, everted gut sacs from rats orally dosed with 0, 0.05, 0.5 or 5.0 mg Cd daily for 3 weeks were placed in media containing 4 x 10(-5) M Ca. Tissue content of calcium after 1 hour incubation was approximately 1.5 times greater for the 5-mg Cd dose. Serosal fluid content of calcium was decreased by the 0.5- and 5-mg Cd/day doses. In other experiments, gut sacs were incubated in bathing media containing 4 x 10(-5) Ca and Cd in concentrations of 10(-4) to 10(-2) M. Tissue and serosal fluid uptake of calcium decreased as Cd concentration increased. To determine the effects of cadmium on the accumulation of calcium against a concentration gradient, equimolar concentrations of Cd were placed in the mucosal and serosal fluids. Cadmium was added to the mucosal fluid. The accumulation of calcium was abolished by 1.5 x 10(-4) M Cd while at 10(-6) M Cd the accumulation was decreased to one-third the control value. The results indicate that acute or chronic exposure of the intestine to cadmium decreases the intestinal absorption of calcium.