Inhibition of cadmium-induced hypertension in rats.

In a low cadmium environment, adding 10 parts per million (ppm) of cadmium to the drinking water of rats for 3 to 18 months induced increases in systolic pressure averaging 12 to 18 mm Hg. The pressor effect of the cadmium was inhibited by adding 3.6 ppm of selenium or 200 ppm of zinc to the drinking water or by dissolving the cadmium in hard water rather than deionized water. A second experiment with 2.5 ppm of cadmium and smaller amounts of selenium and zinc was confirmatory. Exposure to 10 ppm of cadmium increased renal, hepatic, and cardiac cadmium many fold from barely detectable control levels; however, the increases were much less when the cadmium was dissolved in hard water. Cadmium exposure also increased tissue zinc by 30 to 60%. The addition of selenium to cadmium further increased cardiac cadmium, but the addition of zinc to cadmium had no further effect on tissue cadmium. Tissue selenium concentrations were suggestively but not significantly higher following selenium exposure. Cadmium alone, or combined with selenium or zinc, increased renal copper; while the combination of cadmium and selenium increased hepatic copper.