Placental transfer of thiamine in the human subject: in vitro perfusion studies and maternal-cord plasma concentrations.

摘要: Abstract The transfer of thiamine across human placenta has been studied in an vitro perfusion system. With the maternal and fetal perfusates not recirculated, index (ratio clearance to that l -glucose) toward fetus was 2.09 ± 0.36, suggesting a mediated transport In reverse direction, rate approximates expected from simple diffusion (transfer 0.78 0.25). Stepwise increases concentration perfusate were associated with parallel rates up 500 nmol/L. Above concentration, increase declined fell. When recirculated circulation kept open, rapidly decreased, reaching plateau 30 40 minutes at level about 0.1 0.2 perfusate. contrast, within greatly exceeded those perfusates. observations indicate effective system directed fetus, saturable low concentrations capable establishing transplacental gradient. Measurement 20 paired samples plasma obtained term demonstrated mean (± SD) cord:maternal ratio 2.5 1.4. Differential protein binding excluded as cause vivo gradient is probably attributable placental transport.