Owens J A, Falconer J, Robinson J S
J Dev Physiol. 1987 Jun;9(3):225-38.
The effect of restriction of placental growth on the supply of glucose to the gravid uterus and fetus and on fetal and utero-placental metabolism of glucose and lactate was examined in this study. Endometrial caruncles were removed from 13 sheep (caruncle sheep) prior to mating, which restricted placental growth in the subsequent pregnancy. Half the fetuses of caruncle sheep were small or growth retarded, with the remainder normal in size. After insertion of vascular catheters at 110 days gestation, the caruncle sheep, together with 16 control sheep, were studied between 121 and 130 days of gestation. Glucose delivery to and consumption by the gravid uterus and its contents, both as a total and per kg of tissue mass, was significantly lower in caruncle ewes with small fetuses, although glucose extraction was similar to that in controls. Utero-placental glucose consumption was significantly lower in caruncle ewes carrying small fetuses compared to that in control ewes, both as a total and per kg of placenta. Small caruncle fetuses were hypoxaemic and hypoglycaemic and the lactate concentration in the common umbilical vein was significantly higher than in control sheep. Glucose delivery to and consumption by the fetus was significantly lower in normal-sized and in small caruncle fetuses compared to controls. Fetal glucose consumption per kg of fetus was similar in control and caruncle sheep. Fetal glucose extraction increased as fetal weight decreased. Utero-placental production of lactate was similar in control and caruncle ewes. However, uterine output of lactate decreased as placental weight fell. Utero-placental production of lactate per kg of placenta was significantly higher in caruncle ewes compared to controls and increased as oxygen content in blood from the fetal femoral artery decreased. Fetal lactate consumption per kg of fetus increased as the concentration of lactate in blood from the common umbilical vein increased. It is concluded that intrauterine growth retardation due to restriction of placental growth is associated with a reduced supply of glucose to both the pregnant uterus and fetus and a redistribution of glucose therein to the fetus, both directly as glucose and indirectly as lactate. This reflects the disproportionate maintenance of fetal weight relative to that of the placenta, reduced utero-placental consumption of glucose per kg of placenta, conversion of a greater proportion of that glucose or other substrate(s) to lactate by the placenta and an increase in the fraction of the lactate produced by utero-placental tissues that is secreted into the fetal circulation.
本研究检测了胎盘生长受限对妊娠子宫和胎儿葡萄糖供应以及胎儿和子宫 - 胎盘葡萄糖与乳酸代谢的影响。在13只绵羊（肉阜绵羊）交配前切除子宫内膜肉阜，这限制了随后妊娠中的胎盘生长。肉阜绵羊的胎儿中有一半体型小或生长迟缓，其余胎儿大小正常。在妊娠110天时插入血管导管后，在妊娠121至130天期间对肉阜绵羊以及16只对照绵羊进行了研究。怀有小胎儿的肉阜母羊中，妊娠子宫及其内容物的葡萄糖输送量和消耗量，无论是总量还是每千克组织质量，均显著低于对照，尽管葡萄糖摄取与对照相似。与对照母羊相比，怀有小胎儿的肉阜母羊子宫 - 胎盘葡萄糖消耗量显著降低，无论是总量还是每千克胎盘。肉阜小胎儿存在低氧血症和低血糖症，脐静脉中乳酸浓度显著高于对照绵羊。与对照相比，正常大小和肉阜小胎儿的胎儿葡萄糖输送量和消耗量均显著降低。对照绵羊和肉阜绵羊每千克胎儿的胎儿葡萄糖消耗量相似。胎儿葡萄糖摄取量随胎儿体重下降而增加。对照母羊和肉阜母羊子宫 - 胎盘乳酸生成量相似。然而，随着胎盘重量下降，子宫乳酸输出量减少。与对照相比，肉阜母羊每千克胎盘的子宫 - 胎盘乳酸生成量显著更高，并且随着胎儿股动脉血液中氧含量降低而增加。随着脐静脉血液中乳酸浓度增加，每千克胎儿的胎儿乳酸消耗量增加。得出的结论是，由于胎盘生长受限导致的宫内生长迟缓与妊娠子宫和胎儿的葡萄糖供应减少以及其中葡萄糖向胎儿的重新分配有关，葡萄糖既直接以葡萄糖形式，也间接以乳酸形式进行重新分配。这反映出胎儿体重相对于胎盘的维持比例失调、每千克胎盘的子宫 - 胎盘葡萄糖消耗量减少、胎盘将更大比例的葡萄糖或其他底物转化为乳酸以及子宫 - 胎盘组织产生的乳酸分泌到胎儿循环中的比例增加。
