Abstract
Effects of glutathione depletion by L-buthionine-SR-sulfoximine (BSO), a selective inhibitor of γglutamylcysteine synthetase, and metallothionein induction by zinc on the cytotoxicity of cadmium (Cd) were investigated in cultured Chinese hamster V79 cells. Cd toxicity increased with increased duration of BSO treatment which was paralleled with decrease in the level of cell glutathione. Metallothionein (MT) synthesis by zinc was induced with a lag time of 2 h and reached a maximum 10 to 12 h after zinc addition. Presence of BSO did not very much influence MT synthesis by zinc. Preinduction of MT suppressed Cd toxicity almost completely, even on the induction in the presence of BSO. From these observations, it is proposed that glutathione and MT have cooperative protective roles against Cd toxicity, as an initial defense for the former and a second-stage defense for the latter.
