Xanthate effects on cadmium intracellular distribution in rainbow trout (Oncorhynchus mykiss) gills

The uptake of ¹⁰⁹cadmium through perfused rainbow trout gills in the presence of xanthates was studied, and the subcellular distribution of cadmium in perfused gill tissue was determined. Pnenol absorption was also studied because xanthates form hydrophobic Cd complexes with a log P_{octanol/water} similar to that of phenol.

1. Xanthate concentrations higher than 10⁻⁵ M increased the rate of cadmium transfer through the gills and cadmium retention in gill tissue. Cadmium was present as a hydrophobic complex at this and higher xanthate concentrations.

2. A redistribution of cadmium from metallothionein to high molecular weight cadmium binding fractions occurred in the presence of 10⁻⁴ M xanthate.

3. The rate of phenol transfer across the gill epithelium was much higher than the rate of cadmium transfer regardless of whether xanthate was present. The rate of phenol transfer stabilized much faster than the rate of cadmium transfer irrespective of whether xanthate was present, indicating that different uptake mechanisms were involved.

We conclude that in the presence of xanthate concentrations higher than 10⁻⁵ M cadmium is taken up as a hydrophobic Cd(xanthate)₂ complex by the epithelial cells. Within the cell the complex dissociates, and the metal ion is bound to intracellular cadmium-binding ligands. The metal is probably translocated through the basolateral membrane as a free ion.