Tibben E A, Holland R A, Tyndale-Biscoe C H
School of Physiology and Pharmacology, University of New South Wales, Kensington, Australia.
Respir Physiol. 1991 Apr;84(1):93-104. doi: 10.1016/0034-5687(91)90021-a.
The measurements reported here are the first to be made on oxygen carriage of a prenatal marsupial. The oxygen equilibrium curves (OECs) of tammar wallaby blood 1-2 days before the due date of birth showed a high P50 (mean = 44 Torr at 36 degrees C at a PCO2 of 34 Torr), more than 1.5 times that of the mother. This was confirmed by measurements in red cell suspensions at controlled pH. The finding of a higher P50 than in adult is in contrast to the general finding in eutherian (placental) mammals. Also they showed interaction between O2 and CO2 carriage (expressed as delta log P50/delta log PCO2 between 34 and 64 Torr PCO2) about half the magnitude of that in adults. At high PCO2 this effect reversed in the lower part but not in the upper part of the OEC. The Hill plot of the OECs showed a bend in the middle range of saturation: in nearly all cases the Hill coefficient (nH) was greater than 4.0 above about 50% saturation suggesting aggregation of haemoglobin tetramers. These results are similar to those previously reported for neonatal tammars and confirmed by further measurements in this study. The prenatals all had four haemoglobin types, identical with those found in the neonates.
此处报告的测量结果是首次对有袋类动物产前氧气携带情况进行的测量。在出生预产期前1 - 2天的帚尾袋鼩血液的氧平衡曲线（OECs）显示出较高的P50（在36摄氏度、PCO2为34 Torr时，平均值为44 Torr），是母体的1.5倍以上。这在受控pH条件下的红细胞悬液测量中得到了证实。P50高于成年动物的这一发现与真兽亚纲（胎盘）哺乳动物的一般发现相反。此外，它们还显示出氧气和二氧化碳携带之间的相互作用（在34至64 Torr PCO2之间表示为δlog P50/δlog PCO2），约为成年动物的一半。在高PCO2时，这种效应在OEC的下部逆转，但在上部未逆转。OECs的希尔图在饱和度的中间范围内出现弯曲：在几乎所有情况下，希尔系数（nH）在饱和度约50%以上时大于4.0，表明血红蛋白四聚体发生聚集。这些结果与先前报道的新生帚尾袋鼩的结果相似，并在本研究中通过进一步测量得到证实。产前动物均有四种血红蛋白类型，与新生动物中发现的相同。
