Olson E B, DeWolf R E, Rankin J
Life Sci. 1983 Jan 24;32(4):321-7. doi: 10.1016/0024-3205(83)90077-2.
We compared the ability of isolated perfused lungs from previable, 26-day gestation, fetal rabbits; newborn rabbits (within 12 hours of birth) and 3 month old adult rabbits to metabolize a 20-second bolus of norepinephrine (NE). The concentration of NE infused was much below the Km for the NE uptake process to assure first order uptake kinetics. At these low concentrations no vasoactivity was observed. The retention time of a vascular marker dye was monitored as an index of pulmonary vascular surface area. In all three sizes of lungs perfusate flow was adjusted to produce an approximately 7 second dye retention time. At these flow adult and newborn lungs inactivate about 50 to 60 percent of the infused NE. In contrast, fetal rabbit lungs inactivate about 80 percent of the infused NE. We conclude that circulating NE is most avidly taken up and metabolized during fetal lung development. The physiologic significance of this fetal NE inactivation remains unknown.
我们比较了来自妊娠26天、尚未存活的胎兔、新生兔（出生后12小时内）和3个月大成年兔的离体灌注肺代谢20秒推注去甲肾上腺素（NE）的能力。注入的NE浓度远低于NE摄取过程的米氏常数，以确保一级摄取动力学。在这些低浓度下，未观察到血管活性。监测血管标记染料的保留时间作为肺血管表面积的指标。在所有三种大小的肺中，调整灌注液流量以产生约7秒的染料保留时间。在这些流量下，成年和新生兔肺使约50%至60%注入的NE失活。相比之下，胎兔肺使约80%注入的NE失活。我们得出结论，在胎儿肺发育过程中，循环中的NE最容易被摄取和代谢。这种胎儿NE失活的生理意义尚不清楚。
