Effect of excess zinc on cadmium disappearance from rat plasma following intravenous injection.

Studies of the interaction of zinc and cadmium in the isolated perfused rat liver indicate that excess zinc in the perfusion medium inhibits cadmium uptake by the liver. In order to verify these observations in vivo, the effect of excess zinc on cadmium clearance from plasma in the intact rat was investigated at two cadmium dose levels, 0.15 and 0.30 mg Cd/kg of body weight. Cadmium disappearance from plasma was inhibited by excess zinc in a dose related manner at both cadmium dose levels. Greatest inhibition (55%) of cadmium clearance was attained at a Zn:Cd molar ratio of 17, the highest ratio investigated. Excess zinc in plasma (concentrations in plasma greater than 200 mumole/L) resulted in an increase in the volume of distribution of cadmium. A suggested explanation for this effect was displacement of albumin bound cadmium by excess zinc.