THE EFFECTS OF CADMIUM AND COPPER ON THE RENAL UPTAKE AND METALLOTHIONEIN BINDING OF GOLD IN THE RAT AND HAMSTER

Rats and hamsters, pretreated with Cu and Cd, were used to investigate whether species-differences in renal metallothionein synthesis in response to Au were determined by changes in the kidney concentrations of other metals. The effects of dietary Cu limitation and excess on the renal metabolism of Au also were studied in the rat. In this species, all pretreatments affected the renal concentrations of total and metallothionein-bound Cu, but none altered the kidney uptake or thionein-binding of Au. Incorporation of Zn into the metallothionein, which accompanied the binding of Au in this fraction of the kidney, was influenced slightly by pretreatments. In hamsters, pretreatment with Cd, which increased the concentrations of total and thionein-bound Zn in the kidneys, also did not affect the renal uptake of Au, although it significantly increased the binding of Au to the metallothionein fraction of the renal cytosol. This increased binding of Au also was accompanied by increases in the Zn and Cu contents of the metallothionein; The contents of total and thionein-bound Cd remained essentially unchanged. Concentrations of Cu and Zn in the hamster kidney were not affected significantly by s.c. administration of Cu alone (5 daily doses of 3.2 mg Cu/kg body wt), but were increased when Au was given during the Cu-treatment. The concentrations of Au, Cu and Zn in the renal metallothionein fraction also were increased under these conditions. Kidney metallothionein synthesis in response to Au may have been related to the changes in the concentration or distribution of Zn, rather than Cu.