Metallothionein accumulation in response to cadmium in a clonal rat liver cell line

RLC cells, a clonal line of cells derived from rat liver, accumulate ¹⁰⁹Cd in a unique bound form in response to exposure to Cd²⁺. Cadmium administration also causes increased incorporation of ³⁵S]cystine into a chromatographically distinct macromolecule. The ¹⁰⁹Cd-binding activity and the macromolecule preferentially labeled by ³⁵S]cystine cochromatograph both on gel filtration and ion exchange columns. In addition, the Cd²⁺ responsive ³H]cystine-labeled moiety of RLC cells cochromatographs in both systems with rat liver ³⁵S]cystine metallothionein labeled in response to Cd²⁺ challenge in vivo. These data suggest that RLC cells are able to accumulate authentic metallothionein in culture in response to Cd²⁺ challenge. Time course and concentration data for metallothionein accumulation and labeling with ¹⁰⁹Cd and ³⁵S]cystine are presented. RLC cells in culture appear to be able to accumulate Cd²⁺ into metallothionein at a rate comparable to rat liver tissue in vivo when both systems are maximally activated.