Abstract
Summary
The distribution of radioactivity in body fat and organs, 24 hours after administration of radiolabeled ethynylestradiol-3-cyclopentyl ether (EECPE), ethynylestra-diol (EE) and 17 β-estradiol (E2) has been studied in castrated female rats. Radioactivity was highest in various types of fat of EECPE-treated animals. Only 1/10-1/30 as much tritium was detected in fat of rats treated with EE or E2. Each steroid exhibited an individual preference for each particular type of fat. Concentration of steroid in the various organs did in general correspond to the amount of fat present. Free (ether soluble) metabolites were in general more concentrated in organs than in plasma whereas water soluble metabolities (presumably conjugates) were generally higher in plasma than in the various organs. The data on the 3H/14C ratio suggests that the 14C labeled cyclopentyl group is cleaved from EECPE and eliminated via the kidney at a faster rate than the steroid moiety. The distribution of radioactivity in different brain areas following administration of radiolabeled EECPE was studied in male albino rats. EECPE is not uniformly distributed throughout the brain, but rather localized to specific areas. Rate of release of stored EECPE seems to be dependent upon metabolic turnover rather than binding capacity of the components of the different areas.
Get full access to this article
View all access options for this article.