Wallace M J, Hooper S B, Harding R
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Am J Physiol. 1996 Jan;270(1 Pt 2):R33-40. doi: 10.1152/ajpregu.1996.270.1.R33.
Our aim was to determine the role of the fetal adrenal glands in the gestational age-related increase in the ability of epinephrine to induce the reabsorption of lung liquid. Fetal lung liquid volumes and secretion rates were measured in five chronically catheterized control and six bilaterally adrenalectomized (ADX) fetal sheep at approximately 5-day intervals from 120 to 144 days of gestation (term approximately 146 days). The ability of epinephrine to induce the reabsorption of fetal lung liquid was then determined on day 144. Fetal adrenalectomy prevented the preparturient increase in fetal plasma cortisol and 3,5,3'-triiodothyronine (T3) concentration and significantly reduced the gestational age-related increase in fetal lung liquid volumes and secretion rates. Close to term (144 days), epinephrine infusions caused a significantly greater rate of lung liquid reabsorption in control (32.2 +/- 4.8 ml/h) compared with ADX (3.7 +/- 0.7 ml/h) fetuses. We conclude that the presence of the fetal adrenal glands is necessary for the age-related increase in 1) the lung liquid secretion rate and 2) the ability of the fetal lung to reabsorb liquid late in gestation. It is likely that cortisol is the active adrenal hormone involved, supporting the theory that cortisol plays a crucial role in the clearance of lung liquid at birth.
我们的目的是确定胎儿肾上腺在肾上腺素诱导肺液重吸收能力与胎龄相关增加过程中的作用。在妊娠120至144天（足月约146天）期间，以大约5天的间隔，对5只长期插管的对照胎儿绵羊和6只双侧肾上腺切除（ADX）的胎儿绵羊测量了肺液体积和分泌速率。然后在第144天测定肾上腺素诱导胎儿肺液重吸收的能力。胎儿肾上腺切除术阻止了产前胎儿血浆皮质醇和3,5,3'-三碘甲状腺原氨酸（T3）浓度的增加，并显著降低了与胎龄相关的胎儿肺液体积和分泌速率的增加。接近足月（144天）时，与ADX（3.7±0.7 ml/h）胎儿相比，对照胎儿（32.2±4.8 ml/h）输注肾上腺素导致肺液重吸收速率显著更高。我们得出结论，胎儿肾上腺的存在对于以下与胎龄相关的增加是必要的：1）肺液分泌速率；2）妊娠后期胎儿肺重吸收液体的能力。可能皮质醇是起作用的肾上腺激素，支持了皮质醇在出生时肺液清除中起关键作用的理论。
