A Soluble Cadmium-Binding Component in Rat and Dog Spleen

Abstract

• The spleens of cadmium-treated Sprague-Dawley rats and mongrel dogs were examined for cytoplasmic soluble cadmium-binding moieties following the cessation of parenteral cadmium exposure. Cell homogenates prepared in 0.25M sucrose were centrifuged at 29,000 g and the supernatant fractionated on a fractionating column (Sephadex G-75). Ultraviolet absorbing peaks that showed characteristically high 250-nm to 280-nm absorbences were further analyzed for cadmium content by atomic absorption spectrophotometry. Cadmium-binding fractions isolated from the spleens of both species were characteristically similar to rat kidney metallothionein-like substances isolated and identified by the same procedure. Molecular weights for the canine and rat spleen cadmium- binding components were estimated at 14,783±343 and 13,916±490, respectively. These preliminary data indicate the production and persistence of soluble metallothionein-like substances in spleen that bind and retain cadmium ions long after cadmium exposure has ceased.