An experiment using rats was carried out to evaluate the effects of calcium deficiency on the interaction of cadmium (Cd) and zinc (Zn) in vivo.
Eighty-four female rats were divided into two groups. One group was fed a calcium-sufficient diet (normal Ca group), and a second group was fed a calcium-deficient diet (low Ca group). These two groups were divided into 4 subgroups. The diet of subgroup I was supplemented with 50μg/g of Cd, that of subgroup II with 50μg/g of Zn, and that of subgroup III with 50μg/g of Cd and Zn, Subgroup IV served as the control group.
After 5 months on this regimen, the rats were killed and metal levels in the liver, the right kidney, the blood and the femur were analyzed. The left kidneys were examined histopathologically.
The results were as follows:
1) Growth retardation was observed in the low Ca group especially in subgroups I and III.
2) Whereas renal Cd concentrations in subgroup I were higher than those in subgroup III for the normal Ca group, the reverse was found in the low Ca group. Similar findings were also observed in the cases of renal Zn and Cu.
3) Zn in the liver increased with the administration of Cd in the low Ca group. Zn levels in the blood of the low Ca group were higher than those in the normal Ca group.
4) Ca in the femur decreased with the administration of Cd in the normal Ca group. For the low Ca group, Ca concentrations in each subgroup were lower than those of each corresponding subgroup of the normal Ca group. Ca/P ratios of the low Ca group and of the metal administered subgroups in the normal Ca group were lower than those of subgroup IV in the normal Ca group.
5) No significant histopathologic changes in the kidney were found in the normal Ca group but slight changes were observed in some animals of the low Ca group regardless of which metal was administered.
From these results, the interaction of Cd and Zn on renal accumulations of Cd has been shown to be disturbed by a Ca deficient condition.
