胎羊肺液量急性改变后的恢复情况

Restoration of lung liquid volume following its acute alteration in fetal sheep.

作者信息

Dickson K A, Harding R

机构信息

Department of Physiology, Monash University, Clayton, Victoria, Australia.

出版信息

J Physiol. 1987 Apr;385:531-43. doi: 10.1113/jphysiol.1987.sp016506.

DOI:10.1113/jphysiol.1987.sp016506

PMID:3656167

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1192359/

Abstract

The experiments were aimed at determining the means by which lung liquid volume is controlled in fetal sheep. Six unanaesthetized chronically catheterized fetuses between 121 and 144 days of gestation were used in experiments in which lung liquid volume was acutely reduced or increased. 2. The effects on lung liquid volume, secretion and flow in the trachea were continuously monitored until the original volume was restored. Tracheal pressure, breathing activity, electrocortical activity and laryngeal adductor muscle activity were also monitored. 3. Following a mean reduction in lung liquid volume of 54.1% (40.0 +/- 4.3 ml) there was a reduction in tracheal pressure of 1.91 +/- 0.26 mmHg. There was no change in the rate of lung liquid secretion and there was a near cessation in its rate of efflux from the trachea. Influx of liquid from the upper airway was rarely seen. 4. 5 h after its reduction, lung liquid volume had returned to control values. Tracheal pressure and the rate of liquid flow in the trachea returned to control values over 7-8 h. 5. In the hour following the reduction in lung liquid volume the incidence and amplitude of fetal inspiratory muscle electromyogram (e.m.g.) activity were reduced by 19% and 28% respectively. There was no change in laryngeal adductor muscle activity or in the duration of fetal sleep states. 6. When lung liquid volume was increased by 25.4 +/- 3.1 ml tracheal pressure increased by 2.01 +/- 0.17 mmHg. Although there was no change in the rate of liquid secretion there was a rapid efflux of liquid from the trachea principally during epochs of fetal breathing activity thus returning lung liquid volume to its control value. 7. Following the increase in lung liquid volume there were no changes in the incidence or amplitude of fetal inspiratory muscle activity, the activity of laryngeal adductor muscles or in the duration of sleep states. 8. It is concluded that following its alteration in fetal sheep lung liquid volume is restored by passive means. There was no evidence of volume-receptive neural reflexes being activated in defence of lung liquid volume.

摘要

这些实验旨在确定胎儿绵羊肺液体积的控制方式。实验使用了6只妊娠121至144天、未麻醉且长期插管的胎儿，在实验中肺液体积被急性减少或增加。2. 持续监测对肺液体积、气管分泌物和流量的影响，直至恢复到原始体积。还监测了气管压力、呼吸活动、皮层电活动和喉内收肌活动。3. 在肺液体积平均减少54.1%（40.0±4.3毫升）后，气管压力降低了1.91±0.26毫米汞柱。肺液分泌速率没有变化，气管流出速率几乎停止。很少见到上呼吸道液体流入。4. 肺液体积减少5小时后，已恢复到对照值。气管压力和气管内液体流速在7至8小时内恢复到对照值。5. 在肺液体积减少后的1小时内，胎儿吸气肌肌电图（e.m.g.）活动的发生率和幅度分别降低了19%和28%。喉内收肌活动或胎儿睡眠状态持续时间没有变化。6. 当肺液体积增加25.4±3.1毫升时，气管压力增加2.01±0.17毫米汞柱。尽管液体分泌速率没有变化，但主要在胎儿呼吸活动期间，液体从气管迅速流出，从而使肺液体积恢复到对照值。7. 肺液体积增加后，胎儿吸气肌活动的发生率或幅度、喉内收肌活动或睡眠状态持续时间均无变化。8. 得出的结论是，在胎儿绵羊中，肺液体积改变后通过被动方式恢复。没有证据表明为保护肺液体积而激活了容量感受性神经反射。