Magnesium: a competitive inhibitor of lead and cadmium. Ultrastructural studies of the human amniotic epithelial cell.

The measure of the ratio between the volume of intercellular space (R1), the microvilli (R2), and the podocytes (R3) versus the cell volume indicates the effect of lead (Pb) and cadmium (Cd) on the ultrastructure of the human amniotic epithelial cell. Cd decreased R1 significantly, increased R2 and had no effect on R3. Pb had no effect on R1 or R3 but decreased R2 significantly. The addition of Mg chloride to the bathing medium antagonized the effect of Cd on the intercellular spaces and podocytes. The antagonistic effect of Mg on Pb was observed only on microvilli. These results are consistent with the data obtained with electrophysiological studies which show that Mg is a competitive inhibitor of Pb and Cd.