Smith F G, Smith B A, Segar J L, Robillard J E
Department of Pediatrics, University of Iowa, Iowa City 52242.
J Dev Physiol. 1991 Mar;15(3):133-8.
The transition from fetal to newborn life is associated with significant endocrine changes. Some of these changes may be triggered by the effects of spontaneous respiration, increased oxygenation and removal of the placental circulation at birth. We, therefore, studied endocrine function during in utero ventilation, oxygenation and cord occlusion, in nine chronically-instrumented fetal sheep aged 137 to 140 days of gestation. During the sequential effects of in utero ventilation and oxygenation, plasma renin activity (PRA) and angiotensin II (AII) remained at control levels of 6.3 +/- 1.9 ng/ml per h and 66 +/- 15 pg/ml. After cord occlusion, PRA increased to 10.3 +/- 2.2 ng/ml per hr and AII increased to 86 +/- 24 pg/ml, the latter being non-significant. Plasma cortisol levels also increased from control levels of 3.5 +/- 1.0 to 6.7 +/- 0.8 g/dl during cord occlusion (P = 0.02). During the sequential effects of ventilation, oxygenation and cord occlusion, plasma epinephrine increased from control levels of 87 +/- 17 to 492 +/- 142 pg/ml (P = 0.04), and plasma norepinephrine levels increased slightly from 620 +/- 112 to 850 +/- 214 pg/ml. These data provide evidence that many of the changes in endocrine function seen at birth result from factors other than spontaneous respiration, oxygenation and umbilical cord occlusion.
从胎儿期到新生儿期的转变伴随着显著的内分泌变化。其中一些变化可能由出生时自主呼吸、氧合增加以及胎盘循环中断的影响所触发。因此，我们研究了9只妊娠137至140天、长期植入仪器的胎儿绵羊在宫内通气、氧合和脐带阻断过程中的内分泌功能。在宫内通气和氧合的连续作用期间，血浆肾素活性（PRA）和血管紧张素II（AII）维持在6.3±1.9 ng/ml每小时和66±15 pg/ml的对照水平。脐带阻断后，PRA增加到10.3±2.2 ng/ml每小时，AII增加到86±24 pg/ml，后者无统计学意义。脐带阻断期间，血浆皮质醇水平也从3.5±1.0的对照水平增加到6.7±0.8 μg/dl（P = 0.02）。在通气、氧合和脐带阻断的连续作用期间，血浆肾上腺素从87±17的对照水平增加到492±142 pg/ml（P = 0.04），血浆去甲肾上腺素水平从620±112略有增加到850±214 pg/ml。这些数据表明，出生时所见的许多内分泌功能变化是由自主呼吸、氧合和脐带阻断以外的因素引起的。
