title: A study of the permeability of the guinea pig placenta to citrate using recirculating placental perfusion technique.
abstract: The role of the guinea pig placenta in fetal citrate metabolism has been studied by perfusing the placenta in situ. The initial citrate concentrations in the perfusate plasma were lower than in the maternal plasma but rose progressively until, in some cases, they exceeded those in the mother. The rise was uninfluenced by intravenous administration of citrate to the mother. Citrate therefore does not enter the perfusate by simple diffusion from the maternal compartment. It may be synthesised within the placenta. From the rate of accumulation of citrate in the perfusate, the supply to the fetus was calculated to be small compared to the fetal metabolic rate. Citrate added to the perfusate became distributed in a space similar to the extracellular space and no change occurred in maternal citrate concentrations. Thus, the placenta does not appear to metabolise citrate or allow transport to the mother.
mesh_terms: D000818:Animals; D002951:Citrates / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D006168:Guinea Pigs; D008431:Maternal-Fetal Exchange; D010477:Perfusion; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D002951:Citrates