Berger R, Jensen A, Krieglstein J, Steigelmann J P
Department of Obstetrics and Gynecology, Justus-Liebig-Universität Giessen, Germany.
J Dev Physiol. 1993 May;19(5):193-6.
There is evidence from fetal sheep near term that cerebral oxygen delivery decreases during a moderate maternal hypoxemia, whereas cerebral oxygen consumption is maintained. However, since in immature fetuses circulatory centralization may be in part ineffective, cerebral concentrations of high-energy phosphates may fall during a moderate maternal hypoxemia due to an insufficient cerebral oxygen supply. On the other hand anaerobic glycolysis may accelerate to prevent the depletion of high-energy phosphates. To determine, whether or not there is an energy failure in the immature fetal brain in this situation, we studied the effects of 60 min moderate maternal hypoxemia on cerebral concentrations of high-energy phosphates and glycolytic intermediates in fetal guinea pigs at 0.75 gestation. Maternal hypoxemia resulted in no change in fetal mixed arterio-venous pH (7.41 +/- 0.05 vs. 7.38 +/- 0.05; n.s.) or PCO2 (39.0 +/- 4.2 vs. 36.4 +/- 5.6 mmHg; n.s.), but in a fall in fetal PO2 (17.3 +/- 2.2 vs. 11.2 +/- 1.9 mmHg; P < 0.01). There was an increase in fetal cerebral concentrations of lactate (1.50 +/- 0.24 vs. 2.82 +/- 0.91 mumol/g; P < 0.01), whereas those of high-energy phosphates remained unchanged. From these results we conclude that during moderate isocapnic hypoxemia cerebral energy metabolism of immature fetal guinea pigs is maintained by an acceleration of the anaerobic glycolytic rate.
有证据表明，接近足月的胎羊在母体中度低氧血症期间脑氧输送减少，而脑氧消耗维持不变。然而，由于未成熟胎儿的循环集中化可能部分无效，在母体中度低氧血症期间，由于脑氧供应不足，高能磷酸盐的脑浓度可能会下降。另一方面，无氧糖酵解可能会加速以防止高能磷酸盐的消耗。为了确定在这种情况下未成熟胎儿大脑是否存在能量衰竭，我们研究了母体中度低氧血症60分钟对妊娠0.75期豚鼠胎儿脑高能磷酸盐和糖酵解中间产物浓度的影响。母体低氧血症导致胎儿动静脉混合pH值（7.41±0.05对7.38±0.05；无显著差异）或PCO2（39.0±4.2对36.4±5.6 mmHg；无显著差异）无变化，但胎儿PO2下降（17.3±2.2对11.2±1.9 mmHg；P<0.01）。胎儿脑乳酸浓度增加（1.50±0.24对2.82±0.91 μmol/g；P<0.01），而高能磷酸盐浓度保持不变。从这些结果我们得出结论，在中度等碳酸血症低氧血症期间，未成熟豚鼠胎儿的脑能量代谢通过无氧糖酵解速率的加速得以维持。
