PLACENTAL TYROSINE TRANSPORT AND MATERNAL PHENYLKETONURIA

Brush border and basal plasma membrane vesicles prepared from normal h uman placental syncytiotrophoblast have been used to study L-tyrosine transport across placenta in an attempt to investigate the aetiology o f the fetal damage found in maternal phenylketonuria. The results sugg est that competition for transport with a grossly raised L-phenylalani ne concentration at the basal surface of the trophoblast is responsibl e for the suppressed delivery of L-tyrosine to the fetus across the pl acenta.