Metabolic clearance rates of catechol estrogens in rats.
MCRs of the catechol estrogens 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) and of the parent estrogen 17 beta-estradiol (E2) were determined in rats. Long term ovariectomized Wistar rats were infused with the steroids at a constant rate for 3 days via a catheter placed in the abdominal aorta. Blood samples were drawn discontinually by retroorbital puncture, and the serum concentrations of E2, 4-OHE2, and 2-OHE2 were measured by RIA. Steady state was reached within 24 h of infusion. Mean serum MCRs were calculated to be 740 +/- 117 ml/h for E2, 2700 +/- 1000 ml/h for 4-OHE2, and 8300 +/- 1700 ml/h for 2-OHE2. Thus, the MCRs of the catechol estrogens were definitely higher than the MCR of E2 resulting in an apparent ratio of 1:4:11 (E2:4-OHE2:2-OHE2).
D000818:Animals; D002369:Castration; D004958:Estradiol / Q000031:analogs & derivatives* / Q000097:blood; D002393:Estrogens, Catechol; D005260:Female; D008657:Metabolic Clearance Rate; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
D002393:Estrogens, Catechol; D004958:Estradiol; C001390:2-hydroxyestradiol; C014036:4-hydroxyestradiol