Concentration of metallothionein in major organs of rats after administration of various metals.

The effect of various metals (Cd, Cr, Fe, Pb, Mn, Hg, Ni, Zn) at maximum tolerated doses on metallothionein (MT) concentrations in major organs (brain, heart, intestine, kidney, liver, lung, pancreas, spleen, stomach, and testes) of rats was measured by the Cd-radioassay technique. Zn produced the most dramatic changes in MT, increasing concentrations 260-, 86-, 44-, and 14-fold over control for pancreas, intestine, liver, and kidney, respectively. Zn increased MT in every organ examined except brain. Cd was also effective in increasing MT levels, elevating concentrations in all organs except brain and testes. Testes was the only organ in which a metal decreased MT levels, where Cd produced a 90% decrease. Cr, Fe, Pb, and Mn increased MT concentrations only in hepatic tissue, while Hg and Ni increased MT in liver, kidney, and pancreas. Results indicate that Zn is the most effective inducer of MT synthesis in several tissues and that liver appears to be the most responsive organ to increased MT synthesis following exposure to a number of metals.