title: Effect of gestational age on the increase in fetal lung growth following tracheal obstruction.
abstract: 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.
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Keramidaris
authors.forename: S B
authors.initials: SB
authors.lastname: Hooper
authors.forename: R
authors.initials: R
authors.lastname: Harding
mesh_terms: D000402:Airway Obstruction / Q000196:embryology* / Q000503:physiopathology; D000818:Animals; D001835:Body Weight / Q000502:physiology; D003094:Collagen / Q000378:metabolism; D004247:DNA / Q000032:analysis; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006909:Hydroxyproline / Q000032:analysis; D008168:Lung / Q000737:chemistry / Q000196:embryology*; D009929:Organ Size / Q000502:physiology; D011247:Pregnancy; D011506:Proteins / Q000032:analysis; D012756:Sheep; D013936:Thymidine / Q000378:metabolism; D014133:Tracheal Diseases / Q000196:embryology* / Q000503:physiopathology; D014316:Tritium; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D011506:Proteins; D014316:Tritium; D003094:Collagen; D004247:DNA; D006909:Hydroxyproline; D013936:Thymidine