CADMIUM, ZINC AND COPPER IN HORSE KIDNEY METALLOTHIONEIN

Cadium, zinc, and copper were determined in kidney cortex samples and in protein fractions obtained from 20 normal Swedish horses. Cadmium concentrations in kidneys ranged from 0.01 to 1.46 mmole/kg. Zinc concentrations in kidneys increased with increasing cadmium concentrations. At low concentrations of cadmium the increase of zinc was almost equimolar with the increase in cadmium, but at higher concentrations of cadmium the increase of zinc was less pronounced. Copper concentrations ranged from 0.07 to 0.22 mmole Cu/kg and were not related to the cadmium concentration. The increase of zinc in kidney cortex took place in the metallothionein (MT) fractions, where also almost all cadmium was recovered. The molar ratio of zinc and cadmium in MT was close to one at low concentrations (below 0.1 mmole/kg) of cadmium but the ratio decreased with increasing cadmium concentrations in the kidney. This change in molar ratio of zinc and cadmium in MT explains the leveling off in zinc increase at cadmium concentrations in kidney exceeding 0.6 mmole/kg. © 1979.