Bauer C, Jelkmann W, Moll W
Respir Physiol. 1981 Feb;43(2):169-78. doi: 10.1016/0034-5687(81)90007-4.
In order to obtain information on the physiological significance of the difference in oxygen affinity between maternal and fetal blood, we have examined the effect of an acute increase of the oxygen affinity of maternal blood in pregnant rats, on fetal body weight, fetal brain and liver weights, placental weight, and the hematocrit of fetal blood. The increase in oxygen affinity was produced by exchange-transfusing pregnant rats on day 19 of gestation with blood that had been treated previously with sodium cyanate. As a result of the exchange transfusion, the difference in oxygen affinity between maternal and fetal blood essentially disappeared. Pregnant rats exchanged with normal blood served as controls. On day 21 of gestation, the fetal body weight and the fetal liver weight were significantly smaller by 18% and 25% respectively, in the group where the oxygen affinity of the maternal blood was acutely raised when compared to the controls. Also, the hematocrit of the fetal blood was significantly higher in the group where mothers had the high blood oxygen affinity. Placental weight and fetal brain weight were not significantly altered. We infer, that the reduction of fetal weight is due to fetal hypoxia which is caused by the abolishment of the difference in oxygen affinity between maternal and fetal blood. Human infants, whose birth weight is too small for their gestational age have a significantly increased postnatal mortality compared to babies with normal weight. We suppose that the increased mortality of newborns who are too small for their gestational age, represents a selective pressure that has favoured the evolution of a high oxygen affinity of fetal in comparison with maternal blood.
为了获取有关母血与胎儿血氧亲和力差异的生理意义的信息，我们研究了孕鼠母血血氧亲和力急性增加对胎儿体重、胎儿脑重和肝重、胎盘重量以及胎儿血液血细胞比容的影响。通过在妊娠第19天对孕鼠进行换血，输注预先用氰酸钠处理过的血液，来增加血氧亲和力。换血的结果是，母血与胎儿血之间的血氧亲和力差异基本消失。输注正常血液的孕鼠作为对照。在妊娠第21天，与对照组相比，母血血氧亲和力急性升高的组中，胎儿体重和胎儿肝重分别显著降低了18%和25%。此外，母亲血氧亲和力高的组中，胎儿血液的血细胞比容显著更高。胎盘重量和胎儿脑重没有显著变化。我们推断，胎儿体重降低是由于母血与胎儿血之间的血氧亲和力差异消失导致胎儿缺氧所致。出生体重低于其孕周应有体重的人类婴儿，与正常体重的婴儿相比，出生后死亡率显著增加。我们推测，孕周过小的新生儿死亡率增加，代表了一种选择压力，这种压力有利于胎儿血相对于母血高血氧亲和力的进化。
