Schmolling J, Seeger W, Jensen A
Department of Obstetrics and Gynaecology, University of Giessen, Germany.
Reprod Fertil Dev. 1995;7(5):1345-50. doi: 10.1071/rd9951345.
To study lung liquid movements, an isolated lung model, adapted from adult physiology, was developed to measure pulmonary weight changes after the onset of artificial ventilation of lungs from 16 fetal sheep at 0.87 (n = 5), 0.90 (n = 6), and 0.95 (n = 5) of gestation. The fetuses were delivered by Caesarean section. After tracheotomy and thoracotomy under general anaesthesia, a blocked air-free tracheal cannula and a pulmonary arterial catheter were inserted and secured to ensure in situ perfusion of the pulmonary circulation (Krebs-Henseleit buffer) without ventilation before the lungs were removed from the chest and mounted in a specially designed apparatus. Lung weight and pulmonary perfusion pressure were recorded continuously before, during and after the onset of ventilation. After 50 min of ventilation the perfusate was allowed to recirculate and samples were taken at 10-min intervals to determine the concentrations of sodium and the activity of lactate dehydrogenase (LDH) as a marker for cell destruction. In all lungs studied there was a significant removal of lung liquid after the onset of ventilation as assessed by lung weight loss. However, there was a positive correlation between lung weight loss and gestational age of the donor fetuses. These changes were accompanied by a rise in sodium concentrations in the perfusate, possibly suggesting that active sodium transport across the pulmonary epithelium facilitates alveolar liquid removal. As the experiments progressed the lungs regained weight while LDH concentrations increased, indicating that lung cell destruction causing pulmonary oedema may be involved. This pulmonary weight gain was inversely related to gestational age. It is concluded that in isolated ventilated and perfused lungs from fetal sheep, lung liquid removal is an age-related phenomenon that might involve an active sodium transport mechanism. It is further concluded that the development of pulmonary oedema during ventilation is also age related.
为研究肺液运动，我们开发了一种源自成人生理学的离体肺模型，用于测量16只胎羊在妊娠0.87（n = 5）、0.90（n = 6）和0.95（n = 5）时肺人工通气开始后肺重量的变化。通过剖宫产取出胎儿。在全身麻醉下进行气管切开术和开胸术后，插入并固定一根阻塞的无气气管插管和一根肺动脉导管，以确保在将肺从胸腔取出并安装在专门设计的装置中之前，肺循环（克雷布斯 - 亨泽莱特缓冲液）能够原位灌注且不通气。在通气开始前、期间和之后连续记录肺重量和肺灌注压力。通气50分钟后，使灌注液再循环，并每隔10分钟取样以测定钠浓度和乳酸脱氢酶（LDH）活性，作为细胞破坏的标志物。在所研究的所有肺中，通气开始后肺液通过肺重量减轻有显著清除。然而，肺重量减轻与供体胎儿的胎龄呈正相关。这些变化伴随着灌注液中钠浓度的升高，这可能表明跨肺上皮的主动钠转运促进了肺泡液的清除。随着实验进展，肺重量恢复，而LDH浓度增加，表明可能涉及导致肺水肿的肺细胞破坏。这种肺重量增加与胎龄呈负相关。结论是，在胎羊的离体通气和灌注肺中，肺液清除是一种与年龄相关的现象，可能涉及主动钠转运机制。进一步得出结论，通气期间肺水肿的发生也与年龄有关。
