Evidence for a specific transport of D-hexoses across the human term placenta in vitro.
Isolated cotylidons of human term placentas are perfused artificially on the fetal and maternal side. The relative transfer rates of radioactive labelled D-glucose, L-glucose, D-mannose and D-mannitol across the placenta are measured and the inhibition of these transports by phloretin is studied: 1. Transfer rates of D-glucose and D-mannose exceed that of L-glucose about 1.5-4 times. 2. Phloretin (10(-3) mol/l) decreases the transports of D-hexoses, whereas the transport of L-GLUCOSE REMAINS UNAFFECTED. 3. If the concentration of D-glucose is increased, the transport of D-mannose is inhibited competitively. 4. L-glucose and D-mannitol equal in transfer rates. These results show, that D-hexoses cross the human placenta by a specific carrier and by simple diffusion.
D001693:Biological Transport, Active / Q000187:drug effects; D004058:Diffusion; D005260:Female; D005947:Glucose / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism*; D006801:Humans; D008353:Mannitol / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D010693:Phloretin / Q000494:pharmacology; D010920:Placenta / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy
D006601:Hexoses; D008353:Mannitol; D005947:Glucose; D008358:Mannose; D010693:Phloretin