EFFECT OF ETHANOL ON THE DISTRIBUTION OF CADMIUM BETWEEN THE CADMIUM METALLOTHIONEIN-BOUND AND NON-METALLOTHIONEIN-BOUND CADMIUM POOLS IN CADMIUM-EXPOSED RATS

In an attempt to assess the effect of ethanol on cadmium accumulation, metallothionein (MT) synthesis, Cd-binding capacity and lipid peroxidation, rats were administered either Cd, ethanol or their combination for a period of 4 weeks. A significant increase in Cd accumulation was observed in all the organs of rats under study co-exposed to Cd and ethanol as compared to only Cd-treated rats. Increased MT levels in response to Cd were associated with a marked alteration in the distribution of Cd amongst the two pools of intracellular Cd i.e. Cd bound to MT (Cd-MT) and Cd not bound to MT (non-MT-Cd). Higher levels of non-MT-Cd were observed in liver, kidney and heart of Cd + ethanol-exposed rats as compared to only Cd-exposed rats. Lesser binding of Cd-109 to the protein peak was observed in Cd + ethanol-exposed rats than the Cd-treated rats when hepatic supernatants from all the groups were chromatographed on Sephadex G-75 columns, suggesting that ethanol has a redistributing effect on Cd amongst the two pools. A marked increase in lipid peroxidation was observed which was linear to the increase in non-MT-Cd levels. A positive correlation between non-MT-Cd levels and lipid peroxidation was observed in liver, kidney and heart suggesting that non-MT-Cd levels are more crucial and toxicologically more important than total Cd levels.