Plasma estradiol 17-sulfate and 2-hydroxyestradiol 17-sulfate levels and their metabolic clearance rates in rats.

By using highly specific antisera against estradiol 17-sulfate (E2-17-S) and against 2-hydroxyestradiol 17-sulfate (2-OH-E2-17-S), plasma concentrations of these sulfates in Wistar rats were determined. The plasma levels of E2-17-S and 2-OH-E2-17-S in the male were 23.5 +/- 5.3 and 21.6 +/- 6.2 pg/ml, respectively. During the estrus cycle of the female, the plasma concentration of E2-17-S reached its highest level 69.0 +/- 11.8 pg/ml, during the diestrus stage, and its lowest level 36.9 +/- 6.6 pg/ml, during the proestrus stage. Similar tendencies were observed in the case of 2-OH-E2-17-S. To examine the dynamic behavior of both sulfates, the plasma metabolic clearance rate (MCRp) of E2-17-S and 2-OH-E2-17-S were determined by infusion experiments. MCRp of E2-17-S and 2-OH-E2-17-S in male rats were 102 and 653 ml/h (means), respectively, and in female rats were 115 and 644 ml/h (means), respectively. The low MCRp values of both sulfates imply their slow metabolic turn-over.