Effect of Age and Diet on Renal Cadmium Retention in Rats

Abstract

The results of our previous and recent work on cadmium metabolism in relation to age and diet are presented. Experiments were performed on albino rats aged 1-26 weeks. In some experiments rats were given different foods (milk, meat, bread) instead of standard rat diet. Some animals received trisodium calcium salt of diethylenetriaminepentaacetate (DTPA) intraperitoneally to decrease cadmium retention. Radioactive cadmium (ll5mCd) was administered orally and intraperitoneally. Whole body (WB), carcass (C) and organ (kidney, liver and brain) retentions were determined 1 and 2 weeks after a single radioisotope administration. The results are expressed as percentages of the administered dose (% D) and as percentages of whole body (% WB) and carcass (% C) radioactivities.After oral administration whole-body cadmium retention was higher in sucklings than in weaned animals, primarily due to increased gut retention. The kidney retention of orally administered cadmium was about 5-7 times higher in sucklings than in older rats. Cadmium distribution (% C) was similar after oral and intraperitoneal administration. In sucklings, kidney retention made a lower fraction of the carcass radioactivity one week after ll5mCd administration but reached adult values a week later. Liver retention in sucklings was a slightly lower fraction of the carcass radioactivity than in older rats at both time intervals. Brain retention (% C) was about 10 times higher in sucklings than in older rats throughout the experiment.Preliminary data on the influence of dietary treatments and treatment with DTPA indicate that some treatments which influence cadmium retention also influence cadmium distribution. Our results confirm previous findings that sucklings are at a higher risk than adults at the same level of enviroumental exposure to cadmium.