METABOLISM OF OESTRIOL-3-SULPHATE AND OESTRIOL-16(17?)-GLUCOSIDURONATE IN PREGNANT WOMEN

Abstract

ABSTRACT A combination of oestriol-15-3H-3-sulphate (OE3-15-3H-3S) and oestriol-16-14C-16(17?)-glucosiduronate (OE3-16-14C-16(17?)Gl) was administered in the form of a continuous intravenous infusion over 310 and 280 min, respectively, to two women at midpregnancy prior to the interruption of gestation. Eighty and 66 per cent, respectively, of the administered 3H-labelled material and 87 and 83 per cent, respectively, of the 14C-labelled material was recovered within 24 hours from the urine of the two subjects. 3H-labelled OE3-3S and both 3H- and 14C-labelled OE3-16(17?)Gl and oestriol-3-glucosiduronate (OE3-3Gl) were isolated from the urine of both patients in a radiochemically homogeneous form. No 14C-labelled material was found in the OE3-3S isolated. During the continuous infusion period, some 26 per cent of the urinary 3H-labelled material was excreted as OE3-3S, 68 per cent was present as OE3-16(17?)Gl and 6 per cent as OE3-3Gl. Corresponding proportions of the 14C-labelled urinary material were: 97 per cent OE3-16(17?)Gl and 3 per cent OE3-3Gl. During the postinfusion period, the pattern of urinary conjugates showed a marked change: only 2 per cent of the 3H-labelled material was excreted as OE3-3S, 31 per cent was OE3-16(17?)Gl and as much as 67 per cent was OE3-3Gl. Corresponding figures for the 14C-labelled material were: 33 per cent OE3-16(17?)Gl and 67 per cent OE3-3Gl. No radioactive oestrogens other than OE3 were detected. The endogenous urinary oestriol (OE3) excretion during the 24 hours of experiment (expressed in OE3-equivalents) was: 0.086 mg OE3-3S, 1.87 mg OE3-16(17?)Gl and 1.57 mg of OE3-3Gl in the first subject and 0.13 mg OE3-3S, 3.01 mg OE3-16(17?)Gl and 1.53 mg of OE3-3Gl in the second patient. From the relationship between the specific activities of the injected and isolated oestriol conjugates the amount of OE3-3S and OE3-16(17?)Gl reaching the maternal circulation during 24 hours was calculated. On basis of these values it is concluded that in midpregnancy the bulk of oestriol conjugates in the blood consists of glucosiduronates rather than of sulphates and that OE3-3Gl is a quantitatively important urinary metabolite not only of circulating OE3, but also of OE3-3S and OE3-16(17?)Gl.