Toxic metals and human amniotic ion permeability. II. Ultrastructural study and relationship with magnesium

Measurement of the ratio between the volume of the intercellular space (R1), the microvilli (R2), the podocytes (R3), and the nucleus (R4) versus the cell volume indicates the effects of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) on the ultrastructure of the human epithelial cells. R1 is decreased by all toxic metals except Pb. R2 is increased by Cd and As, and decreased by Pb. R3 is not affected. R4 is increased only by As. The addition of MgCl2 to the bathing medium antagonizes the effect of Cd on the intercellular space, of Pb on the microvilli, and of As on nucleus. On the other hand, Mg enhances the effects of Pb on R1 and those of Cd and As on R2. Mg may be either a competitive inhibitor or an activator of the effects of the toxic substances examined in relation to their storage sites.