Lactate transfer across the perfused human placenta.
The transfer of lactate across the human placenta was investigated using an in vitro dually-perfused placental preparation. Using a novel technique, the unidirectional flux of L-lactate was found to be linearly dependent on L-lactate concentration. In addition, unidirectional transfer rates were found to be the same in both maternal-to-fetal and fetal-to-maternal directions at the same lactate concentration. Transfer of [14C]L-lactate was decreased by approximately 15 per cent in competition with unlabelled L-lactate. Stereospecificity and permeability experiments demonstrated the existence of a transfer mechanism which could distinguish between the L- and D-isomers of lactate. Our data suggest that, while a stereospecific carrier for lactate exists in the perfused placenta, the bulk of transplacental lactate transfer takes place by non-carrier-mediated diffusion.
D000983:Antipyrine / Q000378:metabolism; D002250:Carbon Radioisotopes; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007773:Lactates / Q000097:blood / Q000378:metabolism*; D019344:Lactic Acid; D008431:Maternal-Fetal Exchange; D008970:Molecular Weight; D010477:Perfusion; D011247:Pregnancy; D013237:Stereoisomerism
D002250:Carbon Radioisotopes; D007773:Lactates; D019344:Lactic Acid; D000983:Antipyrine