1. Nine-months-old male rats were divided into a normal control group and one experimental group which received eight daily intraperitoneal injections of 15 pmol of 1,25-dihydroxycholecalciferol/100 g body weight. After 5 days, 20 μCi of 109CdCl2 or 20 μCi of 45CaCl2 was administered by stomach tube. The intestinal absorption and tissue retention of the radioisotopes were analysed during the next 3 days, the animals being kept in metabolic cages.
2. The administration of 1,25-dihydroxycholecalciferol caused significantly increased net absorption of intestinal calcium, hypercalcaemia and increased incorporation of calcium into bone. In comparison, there was no significant effect on the intestinal absorption of trace doses of cadmium or upon the accumulation of cadmium in the liver and kidneys.