Renal handling of cadmium and cadmium-metallothionein: studies on the isolated perfused rat kidney.

The isolated kidney perfusion model was used to study the uptake of Cd and metallothionein (MT)-complexed Cd. Cd2+ at concentrations above 40 nM strongly depressed the glomerular filtration rate (GFR), whereas MT-complexed Cd (Cd-MT) at concentrations of 0.8-920 nM had no effect on the GFR. In contrast to Cd2+, Cd-MT was readily reabsorbed by the kidney and uptake saturation for Cd-MT occurred at 240 nM. The maximal transport rate for Cd-MT calculated in this study was 18 pmoles Cd-MT . g-1 . min-1. The accumulation of Cd in the kidney was more efficient in the experiment using Cd-MT, in which case the Cd kidney contents were about 2-4 times higher than compared to CdCl2.