ZINC PREVENTION OF CADMIUM-INDUCED TOXICITY IN OSTEOBLASTIC FUNCTIONS

To obtain further information on the interaction between Cadmium (Cd) and Zinc (Zn) in bone, the effects of Cd or Zn alone, or Cd and Zn together on the osteoblastic cell line, MC3T3-E1, were examined by quantifying protein content, alkaline phosphatase (ALP) activity and hydroxyproline content. The cells were cultured for three days in a medium containing 10% fetal bovine serum. Then the metal ion(s) were added and the cells were cultured for another seven days at 37-degrees-C in air which was 5% CO2. Morphological changes and decreases in ALP activity, protein content, and hydroxyproline content resulting from exposure to 10(-5) M Cd were all reduced or eliminated by adding 10(-4) M Zn to the culture medium with the Cd. Thus, Zn effectively protected the osteoblastic cells from certain toxic effects induced by Cd. The results suggest that the protective effects of Zn against Cd-induced toxicity relate to the function of osteoblastic cells in bone, and that the mechanisms of prevention by Zn are not explainable by the exchange of metal ions in ALP molecules alone.