[The character of human placental glucose and amino acid transport activity (using microvillous membrane vesicles)].
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.
Iioka
H
H
Department of Obstetrics and Gynecology, Nara Medical University.
Moriyama
I
I
Katoh
Y
Y
Itoh
K
K
Hino
K
K
Okamura
Y
Y
Itani
Y
Y
Ichijo
M
M
D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008871:Microvilli / Q000378:metabolism; D010920:Placenta / Q000378:metabolism* / Q000648:ultrastructure; D011247:Pregnancy
D000596:Amino Acids; D005947:Glucose; D000409:Alanine