Absorption and distribution of cadmium (Cd), copper and zinc following oral subchronic low level administration to rats of different binding forms of cadmium (Cd-acetate, Cd-metallothionein, Cd-glutathione).

Male Wistar rats received by gavage saline or about 25 micrograms cadmium (Cd)/kg/day as Cd-acetate (Cd-Ac), Cd-metallothionein (Cd-MT) or Cd-glutathione (Cd-GSH) 5 times per week for 28 times. At all treatments 0.2-0.3% of the totally administered Cd dose was found in liver, kidneys, small intestine and pancreas, whereas none of the Cd forms applied resulted in a Cd accumulation in testes. Cd in small intestine was not increased by Cd-MT. However, it was raised by Cd-Ac and even more by Cd-GSH. A smaller increase in hepatic and renal Cd resulted from Cd-GSH than from Cd-Ac or Cd-MT. Cd in pancreas increased after Cd-GSH but not after Cd-Ac or Cd-MT. Copper (Cu) rose in small intestine and testes but decreased in kidneys independent of either Cd treatment. Concomitantly, zinc (Zn) was decreased in small intestine and testes. The tissue concentration of metallothionein (MT) was only marginally increased by all treatments. The highest value (80%) above controls) was found in small intestine after Cd-GSH. Intestinal Cd as well as testicular Cu were related to the tissue MT. Therefore, the distribution of Cd between various organs depends on the Cd form applied. There is some relationship to the distribution of Cu and Zn.