INVITRO EFFECTS OF CADMIUM, ZINC AND LEAD ON CALMODULIN-DEPENDENT ACTIONS IN ONCORHYNCHUS-MYKISS, MYTILUS SP, AND CHLAMYDOMONAS-REINHARDTII

The potential of cadmium, zinc, and lead to interact with calmodulin (CaM) was investigated by examining in vitro CaM-dependent protein phosphorylation in tissues from rainbow trout (Oncorhynchus mykiss) and sea mussel (Mytilus sp.) and CaM-dependent phosphodiesterase (PDE) activation by algal (Chlamydomonas reinhardtii) extracts. Cadmium, zinc, and lead proved effective in sustaining CaM-dependent protein phosphorylation in systems containing calcium, whereas only lead was capable of CaM activation in systems depleted of calcium. Cadmium lead to a small activation of CaM-dependent PDE activity by algal extracts, corresponding to approximately 25% of that induced by calcium. Cadmium-induced PDE-activation could be attributed to the residual calcium present in the extract. The results indicate that metal-induced CaM activation is primarily mediated in the case of cadmium and zinc by resulting calcium/CaM complexes and in the case of lead by lead/CaM complexes.