A mechanism of cadmium poisoning: the cross effect of calcium and cadmium in the calmodulin-dependent system.

The effects of the intraventricular (IVT) administration of cadmium on the amount of dopamine (DA) in various regions of the mice brain were analyzed immunohistochemically using a microphotometry system. DA levels in the neostriatum and nucleus accumbens were increased by approximately 30% (p less than 0.01) by the IVT administration of CdCl2 (1 mumol/kg). This effect was abolished by the calmodulin antagonist, W-7 (4.2 micrograms/mouse, IVT). The effects of cadmium on DA levels in the brain were very similar to those seen with calcium. Combining these results with our previous finding that calmodulin does not have the ability to distinguish between calcium and cadmium, a mechanism of cadmium poisoning is suggested in which cadmium activates catecholamine synthesizing enzyme and numerous other enzymes through calmodulin-dependent systems, thereby disturbing many functions in the organism.