Jacobs R, Robinson J S, Owens J A, Falconer J, Webster M E
Department of Physiology, University of New England, Armidale, N.S.W., Australia.
J Dev Physiol. 1988 Apr;10(2):97-112.
The effect of prolonged hypobaric hypoxia on fetal sheep was studied. Pregnant ewes were subjected to an atmospheric pressure of 429 torr from 30 days to 135 days gestation (long-term study). Average fetal weight for the hypoxaemic group (3.35 +/- 0.53 kg; n = 4; mean +/- SD) was significantly lower than for the controls (4.23 +/- 0.29 kg; n = 7; P less than 0.05). A short-term study was undertaken with fetuses (n = 8) which were catheterized at 110 days gestation and whose dams were subjected to hypobaric hypoxia from 120 to 141 days gestation. The mean carotid PO2 of fetuses in the hypoxic group was 12.7 +/- 0.7 torr compared to 22.7 +/- 0.7 torr for the control group (n = 9; P less than 0.001) throughout the period of treatment. Fetal arterial oxygen content fell from 6.5 +/- 1.7 to 4.9 +/- 0.4 ml/dl (P less than 0.05), but rose to control values after 7 days due to an increase in fetal haemoglobin concentration (9.6 +/- 1.1 to 13.0 +/- 1.9 g/dl, P less than 0.001) and packed cell volume (33 +/- 3 to 45 +/- 4%, P less than 0.001). In the hypoxaemic fetuses, pH fell initially from 7.34 +/- 0.02 to 7.28 +/- 0.03 (P less than 0.05) and then recovered to 7.32 +/- 0.03 within 24 h. Mean fetal weight of the short-term hypoxic group was 3.46 +/- 0.72 kg compared to 4.15 +/- 0.51 for the control group (P less than 0.05). Both long- and short-term hypoxia produced a similar reduction in fetal body weight. The adrenal glands were significantly heavier in the hypoxic fetuses than in controls. Placental weight was not effected by hypoxia, but exposure from 30 days gestation reduced the average size of cotyledons (P less than 0.05). It is concluded that the fetal sheep increases its ability to acquire and transport oxygen in response to chronic hypoxia, but this compensation is not sufficient to prevent growth retardation or changes to the pattern of tissue growth.
研究了长时间低压低氧对胎羊的影响。将妊娠母羊在妊娠30天至135天期间置于429托的大气压下（长期研究）。低氧组胎羊的平均体重（3.35±0.53千克；n = 4；平均值±标准差）显著低于对照组（4.23±0.29千克；n = 7；P<0.05）。进行了一项短期研究，对妊娠110天时插入导管的胎羊（n = 8）进行研究，其母羊在妊娠120天至141天期间遭受低压低氧。在整个治疗期间，低氧组胎羊的平均颈动脉PO2为12.7±0.7托，而对照组为22.7±0.7托（n = 9；P<0.001）。胎羊动脉血氧含量从6.5±1.7降至4.9±0.4毫升/分升（P<0.05），但由于胎羊血红蛋白浓度升高（从9.6±1.1升至13.0±1.9克/分升，P<0.001）和红细胞压积升高（从33±3升至45±4%，P<0.001），7天后升至对照值。在低氧胎羊中，pH值最初从7.34±0.02降至7.28±0.03（P<0.05），然后在24小时内恢复至7.32±0.03。短期低氧组胎羊的平均体重为3.46±0.72千克，而对照组为4.15±0.51千克（P<0.05）。长期和短期低氧均使胎羊体重出现类似程度的降低。低氧胎羊的肾上腺明显比对照组重。胎盘重量不受低氧影响，但从妊娠30天开始暴露会降低子叶的平均大小（P<0.05）。得出的结论是，胎羊会增加其获取和运输氧气的能力以应对慢性低氧，但这种补偿不足以防止生长迟缓或组织生长模式的改变。
