Metabolism of Ca 45 in Blood,Bones,and Young of Lactating Rats Treated with Estradiol. ∗

Summary

Estrogen, in an amount estimated to equal that secreted in late pregnancy, was injected daily into lactating rats for 4 days along with Ca⁴⁵. On the 5th day, radioactivity of blood serum, bones and young was compared to a similar group of lactating rats not treated with estrogen. Average gain in weight of the litters of the 2 groups was similar. However, radioactivity in serum and bones of treated group was significantly higher than in the controls. The radioactivity in litters of the 2 groups was similar. These data indicate that estrogen plays a role in the retention of calcium by the animal body.