Relationship Between Estradiol and Parathyroid on Retention of Ca 45 in Bone and Blood Serum of Rats. ∗

Summary

Administration of estrogen to normal male rats increased the radioactivity of blood serum following Ca⁴⁵ injection, whereas bone remained unchanged. Parathyroid extract depressed radioactivity of both bone and blood serum but when estrogen was given in addition radioactivity was increased in both. Parathyroidectomy depressed the radioactivity of bones and serum but estrogen again increased the radioactivity of bones slightly and serum significantly. These data indicate that estrogen plays a role in calcium metabolism independent of the parathyroid hormone in aiding retention of calcium.