title: Passage of S(+) and R(-) gamma-vinyl-GABA across the human isolated perfused placenta.
abstract: 1. The maternal to foetal transfers of S(+)- and R(-)-gamma-vinyl-GABA (VGB) across the human isolated perfused placenta were low and comparable with those of acidic alpha-amino acids. 2. The placental uptake of the active S(+)-isomer from the maternal circulation exceeded that of the R(-)-isomer and this was reflected by a corresponding difference in placental tissue concentrations. 3. During perfusion with recirculation of the foetal medium, the two enantiomers were present at a similar concentration and did not concentrate in foetal perfusate, indicating that the excess amount of S(+)-VGB cleared from the maternal circulation was not accessible to the foetal perfusate. Furthermore, stable concentrations of both isomers in the foetal perfusate suggested a lack of placental metabolism. 4. Possible explanations of these findings include the operation of a stereoselective sodium-dependent-GABA placental uptake system on the maternal side, similar to that observed in neuronal tissue, or stereoselective binding to a placental GABA transaminase.
authors.affiliation: Biologie de la Reproduction, Université P. & M. Curie, Paris, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Challier
authors.forename: E
authors.initials: E
authors.lastname: Rey
authors.forename: T
authors.initials: T
authors.lastname: Bintein
authors.forename: G
authors.initials: G
authors.lastname: Olive
mesh_terms: D000614:Aminocaproates / Q000493:pharmacokinetics*; D000927:Anticonvulsants / Q000493:pharmacokinetics*; D000983:Antipyrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D010477:Perfusion; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013237:Stereoisomerism; D020888:Vigabatrin
chemical_list: D000614:Aminocaproates; D000927:Anticonvulsants; D007930:Leucine; D020888:Vigabatrin; D000983:Antipyrine