Accurso F J, Alpert B, Wilkening R B, Petersen R G, Meschia G
Respir Physiol. 1986 Jan;63(1):43-52. doi: 10.1016/0034-5687(86)90029-0.
We describe the temporal characteristics of the response of the fetal pulmonary circulation to the vasodilatory stimulus of a sustained increase in fetal PO2 (5.1 +/- 0.7 Torr) in 13 chronically prepared fetal sheep. Left pulmonary artery blood flow was measured by electromagnetic flow transducer. Fetal PO2 was increased by delivery of 100% oxygen to the ewe and did not significantly change during the 2 h period of oxygen administration. Fetal left pulmonary artery blood flow slowly increased to a peak approximately 2.7 times the control value 40-50 min after the onset of increased PO2. It then steadily declined toward baseline over the next hour of increased PO2. Maximal pulmonary blood flow in response to the increase in PO2 increased with gestational age. Pulmonary arterial, aortic, and left atrial blood pressures did not change significantly in the animals in which measurements were made. We conclude that the changes in fetal pulmonary blood flow with increased fetal PO2 depend upon the time after the PO2 is increased. The adaptation seen during the second hour suggests the existence of mechanisms that tend to keep the fetal pulmonary circulation chronically constricted at any PO2 likely to be encountered in fetal life.
我们描述了13只慢性制备的胎羊胎儿肺循环对胎儿PO2持续升高（5.1±0.7 Torr）的血管舒张刺激反应的时间特征。通过电磁流量传感器测量左肺动脉血流量。通过向母羊输送100%氧气来提高胎儿PO2，在输氧的2小时期间胎儿PO2没有显著变化。胎儿左肺动脉血流量在PO2升高开始后40 - 50分钟缓慢增加至峰值，约为对照值的2.7倍。然后在接下来PO2升高的一小时内稳步下降至基线。对PO2升高的最大肺血流量随胎龄增加而增加。在进行测量的动物中，肺动脉、主动脉和左心房血压没有显著变化。我们得出结论，胎儿肺血流量随胎儿PO2升高的变化取决于PO2升高后的时间。在第二个小时观察到的适应性表明存在一些机制，这些机制倾向于使胎儿肺循环在胎儿生命中可能遇到的任何PO2水平下长期保持收缩状态。
