Placental Transfer of α-Amino Isobutyric Acid and Glucose Near Term and in Progesterone-Induced Prolonged Gestation in the Rat

Abstract

Maternal-fetal transfer of radioactively labelled α-amino isobutyric acid (AIB) and glucose was studied in pregnant rats near term and during progesterone-induced prolonged gestation. Transfer of both substances decreases markedly between day 21 and 22 of normal gestation. This downward trend in the rate of transfer continued during prolonged gestation. The amount of both AIB and glucose per gram of placental or fetal weight crossing into the fetus was reduced approximately 50% between day 21 and 23 of gestation.