Protective effects of calcium antagonists on cadmium-induced toxicity in rats.

Protective effects of calcium antagonists, chlorpromazine (CPZ) and nimodepine (NI-MO), on cadmium-induced toxicity were investigated. After giving CdCl2 (0.44 mg Cd/kg, i.p.), CPZ (5 mg/kg, i.p.) or NIMO (8 mg/kg, p.o.) were administered every day to Sprague-Dawley (S.D.) rats for a week. Then, urinary N-acetyl-beta-D-glucosaminidase (NAG), urinary cadmium and blood cadmium were measured. The accumulation of cadmium in the kidney cortex, content of renal calmodulin, hemoglobin and the ultrastructural damage of proximal convoluted tubules of rats were examined three weeks after the last administration. Results indicated that the calcium antagonists partly protected against toxic effects induced by cadmium in different manners. These data provide further evidence for the new hypothesis that the cross effect of cadmium and calcium in calmodulin regulated systems may be responsible for the mechanism of cadmium intoxication. The results suggested that the calcium antagonists could be a new and promising approach in the therapy of heavy metal-induced diseases.