Placental transport of hexoses: a comparative study with antipyrine and amino acids

A comparative study of the transplacental passage of some labelled hexoses, amino acids and antipyrine leads to the following conclusions: The maternal-fetal transfer of D-glucose, which amounted to 90 per cent of antipyrine, is very efficient. D-glucose, 3-O-methylglucose and 2-deoxyglucose, for which equivalent transfers were obtained, appear to share the same carrier system. L-glucose transport occurs by simple diffusion. 3-O-methylglucose did not accumulate in the placental tissue. Similarly, maternal and fetal concentrations of 2-deoxyglucose were nearly at equilibrium. It is concluded that the transport of D-glucose is not concentrative. These observations provide further evidence of a facilitated diffusion process for the transport of D-glucose across the human placental membrane.