Cadmium uptake in isolated adrenocortical cells of rainbow trout and yellow perch

Cadmium uptake was studied in isolated adrenocortical cells of rainbow trout (Oncorhynchus mykiss) and yellow perch (Perca flavescens) to test the hypothesis that the greater sensitivity of trout cells to Cd-induced disruption of cortisol secretion observed in previous studies is correlated to higher level of metal accumulation. There was no evidence for interspecies differences in accumulation level, and a specific transport mechanism of similar affinity has been characterized in both fish species. However, inhibition of Cd uptake by calcium was observed in rainbow trout exclusively. The free metal ion Cd(2+) and chlorocomplexes CdCl(n)(2-n) both contribute to Cd accumulation with different level of contribution between fish species. We conclude that interspecies differences in sensitivity to Cd endocrine disrupting effect are not necessarily related to different levels of metal accumulation but would rather be linked to transport pathways and metal speciation. Cadmium/calcium competition for uptake could be a determinant of the early Cd-induced impaired cortisol secretion in trout but not perch cells.