Shapiro M I, Roux J F, Harlow A, Massé D
Am J Obstet Gynecol. 1979 Mar 15;133(6):713-7. doi: 10.1016/0002-9378(79)90024-3.
Gonadotropin-injected pregnant rabbits were delivered by cesarean section near term (30 days after conception (term, 31 days) and 3 1/2 and 4 days post term. Lipid metabolism of the postterm and near-term fetus was compared. Fetal and placental uptake of radioactivity and rate of lipid entry into the fetus, as well as fetal and maternal plasma free fatty acid (FFA) specific activities (at equilibrium) were determined following a single maternal injection of [1-14C]palmitate (50 muCi) administered at cesarean section. Evidence of placental malfunction in the postterm period includes decreased placental uptake and transport of labeled FFA occurring while maternal and fetal FFA dynamics (half times) remain unchanged and a loss in "organization": The strong positive correlation (p less than 0.001) between placental uptake and transfer to the fetus at 30 days' gestation is lost 5 days later. A comparison of maternal and fetal plasma FFA specific activities indicates a substantial (62%) near-term fetal contribution to its own circulating FFA pool. Total plasma FFA is elevated in the postterm fetus concomitant with a decreasing maternal supply. A postterm fetus must therefore contribute lipid from its own reserves (probably liver) in excess of amounts attributed to a near-term fetus, i.e., greater than 62%.
给注射促性腺激素的怀孕兔子在接近足月时（受孕后30天（足月为31天）以及超过足月3.5天和4天时）进行剖宫产。比较了过期胎儿和接近足月胎儿的脂质代谢情况。在剖宫产时给母体单次注射[1-14C]棕榈酸酯（50微居里）后，测定了胎儿和胎盘对放射性的摄取、脂质进入胎儿的速率，以及胎儿和母体血浆游离脂肪酸（FFA）的比活性（达到平衡时）。过期期间胎盘功能不全的证据包括：母体和胎儿FFA动态（半衰期）保持不变的情况下，胎盘对标记FFA的摄取和转运减少，以及“组织”功能丧失：妊娠30天时胎盘摄取与向胎儿转运之间的强正相关（p<0.001）在5天后消失。母体和胎儿血浆FFA比活性的比较表明，接近足月的胎儿对其自身循环FFA池的贡献很大（62%）。过期胎儿的血浆总FFA升高，同时母体供应减少。因此，过期胎儿必须从其自身储备（可能是肝脏）中提供脂质，其数量超过接近足月胎儿的脂质数量，即大于62%。
