Metabolism of dehydroepiandrosterone (DHA) in the mature perfused human placenta (I).

A design for the perfusion of one (monoperfusion) or two (parallelperfusion) cotyledos of one placenta was developed for studies of the metabolism of the precursor steroid dehydroepiandrosterone (DHA). Several parameters are used as viability criteria: vascular resistance, glucose and oxygen consumption, lactate/pyruvate ratio, activity of lactate-dehydrogenase (LDH) in the perfusate, extent of perfusion by dye infusion, and morphological description by electron microscopy. A dosage of 2 mg DHA with 2.5 microCi 14C-radioactive labelled marker is given for testing the metabolizing capacity of the placenta. The labelled metabolites DHA, androstenedione (A), testosterone (T), estrone (Oe 1), and estradiol-17 beta (Oe 2) are separated by thin-layer chromatography and measured by scanning and measurements of scraped radioactive spots by scintillation counting. The steroidogenesis is evaluated with the concentrations of Oe 1 at 15 min (Oe 1.15'), Oe 1 + Oe 2 at 90 min (Oe tot, 90'), total aromatization rate (from perfusate and homogenate after 120 min). Results comparable to DHA are found using DHA-sulphate (DHA-S) as precursor, higher amounts of estrogens are metabolized from A. Mature placentas metabolize DHA in relation to the initial DHA concentration: optimal aromatization is found at 250-350 pmol DHA/ml/g, decreased aromatization at higher or lower concentrations. Oe 1 represents the main placental metabolite.