The character of human placental glucose and amino acid transport activity (using microvillous membrane vesicles)
Iioka, H.; Moriyama, I.; Katoh, Y.; Itoh, K.; Hino, K.; Okamura, Y.; Itani, Y.; Ichijo, M.
Nihon Sanka Fujinka Gakkai Zasshi 39(9): 1560-1564
1987
ISSN/ISBN: 0300-9165 PMID: 3681054 Document Number: 288009
To elucidate the character of human placental D-glucose and L-alanine transport activity, we investigated the uptake of D-glucose and L-alanine into microvillous membrane vesicles prepared from human early and term placenta using the rapid filtration technique. 1. The uptake of D-glucose into microvillous membrane vesicles did not depend on the Na+ gradient (extravesicular greater than intravesicular). The uptake of D-glucose into vesicles was three times as great as that of L-glucose. And phloretin prominently inhibited the uptake of D-glucose into vesicles. So, it was indicated that the transport mechanism of D-glucose across microvillous membrane was facilitated diffusion. 2. The uptake of L-alanine into microvillous membrane vesicles depended on Na+ gradient (extravesicular greater than intravesicular), so that the transport mechanism of L-alanine across microvillous membrane was a secondary active one. The transport of L-alanine into vesicles prepared from term placenta increased prominently compared to that of early placenta. On the other hand, the transport activity of D-glucose into vesicles prepared from term placenta did not differ from that of early placenta.