PubMed · 5798277
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I R King. 1969. Amniotomy with or between contractions?. https://pubmed.ncbi.nlm.nih.gov/5798277/
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In this study, the ability of human amniotic epithelial cells to synthesize dopamine from L-3,4-dihydroxyphenylalanine (L-DOPA) was examined. Dopamine synthesis was significantly increased time and L-DOPA concentration dependently, suggesting the presence of an aromatic L-amino acid decarboxylase enzyme. This was confirmed by the decrease in dopamine synthesis in the presence of an aromatic L-amino acid decarboxylase inhibitor, benserazide. These findings suggest that human amniotic epithelial cells have the capacity to take up and convert L-DOPA into dopamine.
Transfer of steroidal and nonsteroidal compounds across guinea pig amnion and chorion laeve was investigated as a function of stage of gestation, tissue orientation, steroid specificity, and molecular size. Each fetal membrane was examined at early and late stages of gestation, before and after pubic symphysis relaxation. Early amnion was impermeable to macromolecules and small charged molecules while [3H]estrone and [3H]pregnenolone were transferred, the latter depending on tissue orientation and involving conjugation at the basolateral interface. After symphysis dilation, amnion transferred all substrates tested with the exception of BSA; the molecular weight cutoff was approximately 5,000. Unlike amnion, early chorion transferred both free and conjugated steroids as well as inorganic sulfate. Transfer of estrone involved conjugation and depended on tissue orientation. Transfer of [3H]estrone-sulfate, [3H]estrone-glucuronide, and [3H]pregnenolone-sulfate was similar despite selective deconjugating activity toward estrone-sulfate. Near term, chorion was impermeable to inorganic sulfate and transfer of estrone-glucuronide depended on tissue orientation, involving deconjugation in the maternal to fetal direction. At no stage of gestation did chorion transfer macromolecules. These results suggest that the transfer of free and conjugated steroids across fetal membranes is differentially regulated by tissue, its stage of development, and direction of transfer.