STUDIES ON THE METABOLISM OF C-19 STEROIDS IN THE HUMAN FOETO-PLACENTAL UNIT.

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Abstract
Dehydroepiandrosterone sulphate (DHAS) labelled with H3 and dehydroepiandrosterone (DBA) labelled with C14 were simultaneously administered into the arterial supply of four placentas perfused in situ immediately following the removal of the foetus at midpregnancy. From the perfused placentas testosterone (T), androstenedione (A), oestrone (OE1) and 17[beta]-oestradiol (OE2) derived from the metabolism of both DHA and DHAS were isolated in a radiochemically homogeneous form. In addition DHA derived from DHAS was isolated. No labelled 19-hydroxy-androst-4-ene-3,17-dione, or 3[beta],19-dihydroxy-androst-5-en-17-one was detected. From the perfusates the same steroids were isolated as from the placentas. They contained so small amounts of H3 that their radiochemical homogeneity could be establfshed only on the basis of the C14 label. The H3/C14 ratio of the A isolated from each placenta was higher than that of DHA and OE1 isolated from the same source, indicating a higher contribution of DHAS to A than to DHA or OE1. However, no conjugated or unconjugated intermediates between DHAS and A other than DHA were detected. One possible explanation for the differences in isotope ratios based on the existence of two hypothetical placental compartments, is discussed.