Retention of cadmium in cadmium-naive normal and iron-deficient rats as well as in cadmium-induced iron-deficient animals.

The retention of cadmium was investigated in cadmium-naive normal and iron-deficient rats in comparison to rats with cadmium-induced iron deficiency. Rats subchronically (4 weeks) exposed to dietary cadmium (28, 56, 112 ppm Cd and 28 ppm Fe) received a radioactively labeled dose of 2 mumol Cd/kg body wt; acutely (no cadmium exposure with diet) treated rats received doses between 1 and 8 mumol Cd/kg body wt. Two animals of each group received iron (1 mumol/kg as 59FeSO4 in order to monitor iron absorption in parallel. After a period of 4 weeks of feeding a cadmium-fortified diet, the test dose was administered and after a 2-weeks period 109Cd and of 59Fe retention was determined. The results showed in part an unexpected pattern of cadmium retention: subchronic feeding of cadmium induced iron deficiency. This implies an immediate interaction between the two metals with regard to intestinal transfer of iron. The retention of iron was increased in the Cd-induced anemia to the same extent as that in iron deficiency induced by iron restriction. Cadmium retention in iron deficiency induced by iron withdrawal also showed a marked increase, which implies that iron deficiency stimulates the intestinal transfer system for both metals in a similar way. Contrary to this effect, the cadmium retention in cadmium-induced iron deficiency was reduced to about 30% of control values. A self-induced aggravation of the body cadmium burden, as a consequence of the iron deficiency which is known to result from subchronic exposure to feeding of dietary cadmium, was thus excluded.