The effects of CdCl2 on the maternal-to-fetal clearance of 67Cu and placental blood flow.

Copper is an essential element while Cd is an extremely toxic heavy metal of questionable biological usefulness. Cadmium has been reported to interfere with the metabolism of Cu, be teratogenic, and decrease blood flow in the fetal placenta. Because of these reported biological interactions of Cd and Cu, this investigation was conducted to determine the effects of Cd on placental transport of 67Cu and placental blood flow in the guinea pig. All guinea pigs used were 60 +/- 1 days pregnant. A placental perfusion technique was used to measure the maternal-to-fetal clearance of 67Cu and 3H2O across the placenta. The clearance of 3H2O served as an indicator of placental blood flow on the maternal side of the circulation. The results indicated that an iv injection of 1 mg Cd/kg body weight resulted in an immediate increase in the clearance of 67Cu which declined over the next 8 min to an elevated level compared to the extrapolated best-fit curve of control values. This iv injection of CdCl2 concomitantly reduced the maternal-to-fetal clearance of 3H2O across the placenta. In conclusion, an acute exposure of the pregnant female to CdCl2 results in an increased maternal-to-fetal clearance of 67Cu and a reduced placental blood flow that can alter the supply of nutrients to the developing embryo or fetus, and therefore modify normal development.

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.