Keramidaris E, Hooper S B, Harding R
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Exp Lung Res. 1996 May-Jun;22(3):283-98. doi: 10.3109/01902149609031776.
The growth response of the fetal lung to increased expansion was compared at two gestational ages. In fetal sheep, lung expansion was increased by occluding the trachea for 48 h at either 112-114 days (younger fetuses) or 125-127 days (older fetuses) of gestation (term is approximately 145 days). After 24 h of tracheal occlusion, the volumes of liquid that could be drained from the lungs were increased by 64.7 and 158% above control in younger and older fetuses respectively; the volumes were not increased further after 48 h. In younger fetuses, 48 h of tracheal occlusion increased (p < .05) fetal lung wet weights (21% above control) and protein contents (43% above control) but not DNA contents. In older fetuses, 48 h of tracheal occlusion increased (p < .05) fetal lung wet weights (61% above control), protein contents (41% above control), and DNA contents (22% above control). However, 48 h of tracheal occlusion did not alter total lung hydroxyproline content at either age, resulting in a reduction in the hydroxyproline/protein ratio of the fetal lungs. The results suggest that the lung growth response to tracheal occlusion is greater at 125-127 days of gestation than at 112-114 days of gestation, probably due to a greater accumulation of lung liquid and hence a greater increase in lung expansion, in older fetuses.
在两个胎龄比较了胎儿肺对扩张增加的生长反应。在胎羊中，分别在妊娠112 - 114天（较年轻胎儿）或125 - 127天（较年长胎儿）（足月约为145天）时，通过气管阻塞48小时来增加肺扩张。气管阻塞24小时后，较年轻和较年长胎儿肺中可引流液体的量分别比对照增加了64.7%和158%；48小时后液体量未进一步增加。在较年轻胎儿中，气管阻塞48小时增加了（p < 0.05）胎儿肺湿重（比对照高21%）和蛋白质含量（比对照高43%），但未增加DNA含量。在较年长胎儿中，气管阻塞48小时增加了（p < 0.05）胎儿肺湿重（比对照高61%）、蛋白质含量（比对照高41%）和DNA含量（比对照高22%）。然而，气管阻塞48小时在两个年龄段均未改变肺总羟脯氨酸含量，导致胎儿肺中羟脯氨酸/蛋白质比值降低。结果表明，妊娠125 - 127天时肺对气管阻塞的生长反应大于妊娠112 - 114天时，这可能是由于较年长胎儿肺液积聚更多，从而肺扩张增加幅度更大。
