Cadmium speciation and transport in the blood of the bivalve Mytilus edulis

Cadmium (Cd) speciation in the blood plasma of Mytilus edulis was investiga ted using the metal speciation model MINTEQA2, In the presence of inorganic ions alone, Cd-chloro complexes dominated the speciation (97% of total Cd) , with 3% as Cd2+. Inclusion Of a novel Cd-binding histidine-rich glycoprot ein (HRG) purified from mussel blood plasma decreased the contribution of c hloro-complexes to 11.9%, with 86.8% of the Cd bound to the HRG and 1.3% pr esent as Cd2+. Cd transfer from the blood plasma to the kidneys in vivo was studied by injecting Cd-109 (both with and without additional chelation) i nto mussels. Oxine and EDTA complexed a significant amount of blood-borne C d (23.7% CdOxine; 57.1% CdEDTA). In the presence of each chelator, plasma r etained significantly more Cd, although there was no significant difference in Cd uptake by tissues (kidney, gill-mantle, and remaining visceral. (C) 2000 Elsevier Science Ltd. All rights reserved.