High cytotoxicity and membrane permeability of Et3Pb+ in mammalian and plant cells.

Cells of mammalian origin as well as those of higher plants appear to be very sensitive to triethyllead ion (Et3Pb+). Neuroblastoma cells kept in the presence of 1 microM Et3Pb+ lost their viability within 6 h. Growth of suspension culture cells of soybean (G. max(L.)Merr.) was inhibited by 1 microM Et3Pb+, and finally the cells died. Morphologically, Et3Pb+ caused the complete breakdown of microtubular structures in neuroblastoma cells; thus microtubules appeared to be the main target for the toxin. While in a previous study the effect of Et3Pb+ on microtubules has been well documented at concentrations of 50-200 microM 1, the present study demonstrates that the formation of microtubules from pig brain tubulin is disturbed at concentrations of Et3Pb+ as low as 0.5 to 1 microM. We conclude from these data that Et3Pb+ freely permeates the plasma membranes of mammalian as well as plant cells.