Cadmium effects in rats on tissue iron, selenium, and blood pressure: blood and hair cadmium in some Oregon residents

Abstract

Exposure of rats to cadmium causes a marked depletion of iron in liver and kidney. Selenium neither counteracts or intensifies the influence of cadmium on tissue iron levels. Selenium injections protect against cadmium-induced testicular damage but cause this element to accumulate in the testes at higher concentration than in animals exposed to cadmium without selenium. Selenium injection diverts the binding of cadmium from low molecular weight proteins to high molecular weight ones. Dosing rats with selenium and cadmium or inclusion of Se or Cd in the diet did not result in altered cadmium binding in tissues, raising some questions concerning the environmental significance of these injection experiments.Addition of selenium to a diet containing cadmium decreased the accumulation of cadmium in liver and kidney, but increased its deposition in testes. The metabolism of cadmium bound to metaliothionein was markedly different as compared to the inorganic salt of this element. Dietary ascorbate, but not citrate or cysteine, decreased the deposition of cadmium in rat tissues. In some low-level exposure experiments with cadmium (1 to 1000 ppb), no differences were found in the percentage of dose absorbed or rate of cadmium accumulation when provided in food versus water. Female rats tended to absorb more cadmium than males. The binding of cadmium to cytosolic proteins was found to be different between rats fed low levels of cadmium (up to 1 ppm) as compared to those fed high levels of this element (100 ppm). Cadmium was not found to contribute to hypertension in rats, and a summary of results by various investigators is presented.Blood and hair cadmium levels in Oregon residents were found to be highest in employees of a mine, and hair cadmium was found to be respectively higher in smokers than nonsmokers and in metal workers than office workers. No relationships were observed in humans between blood or hair cadmium levels and blood pressure.

Participation of metal transporters in cadmium transport from mother rat to fetus

“…It is well known that DMT1 protein levels are upregulated in anemic rats (Thompson et al, 2007;Fleming et al, 1998). It has been reported that oral Cd intake reduces hemoglobin concentration of rat and leads to iron-deficiency anemia (Whanger, 1979;Schumann et al, 1996). In this study, hematocrit and hemoglobin were measured to investigate whether Cd administration caused anemia or not.…”

Cardiovascular diseases and the work environment. A critical review of the epidemiologic literature on chemical factors.

“…One o f the wor st problems concerns the measurem ent of cadm ium exposure. Man y studies estimated the exposure by measur ing cadmium in blood (77,80,124,137,138,140,141,(148)(149)(150)(151)153). The blood cadmium level is, however, not a very reliable mea sure of the cadmium body burden.…”

Cadmium-induced elevation of blood pressure

“…It was found, however, that blood pressure was elevated only when Long-Evans strain rats were fed with cadmium mixed with rye [45]. Schroeder et al [46] reported later that the average elevation in blood pressure was 42 mmHg, almost half of that of the former report, in suckling Long-Evans strain rats given drinking water containing 5 ppm of cadmium acetate over a period of 400 days.…”