title: Dose-response effects of betamethasone on maturation of the fetal sheep lung.
abstract: OBJECTIVE
  Glucocorticoid administration to women in preterm labor improves neonatal mortality and morbidity. Fetal exposure to glucocorticoid levels higher than those appropriate to the current gestational stage has multiple organ system effects. Some, eg, fetal hypertension, are maximal at lower than the clinical dose. We hypothesized that the clinical dose has supramaximal lung maturational effects.
  
  
  METHODS
  We evaluated the full, half, and quarter clinical betamethasone dose (12 mg/70 kg or 170 microg/kg intramuscularly twice 24 hours apart) on fetal sheep lung pressure volume curves (PVC) after 48 hours' exposure at 0.75 gestation. We measured key messenger RNAs and protein products that affect lung function and total lung dipalmitoyl phosphatidyl choline.
  
  
  RESULTS
  Full and half doses had similar PVC and total lung dipalmitoyl phosphatidyl choline effects. Messenger RNA for surfactant proteins A, B, and D and elastin increased in a dose-dependent fashion.
  
  
  CONCLUSIONS
  Half the clinical betamethasone dose produces maximal PVC improvement in fetal sheep at 0.75 gestation.
authors.affiliation: Department of Neurology, University of Jena, Jena, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Loehle
authors.forename: Matthias
authors.initials: M
authors.lastname: Schwab
authors.forename: Susan
authors.initials: S
authors.lastname: Kadner
authors.forename: Kristal M
authors.initials: KM
authors.lastname: Maner
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Gilbert
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Brenna
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Ford
authors.forename: Peter W
authors.initials: PW
authors.lastname: Nathanielsz
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nijland
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000032:analysis; D000818:Animals; D001623:Betamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005325:Fetal Organ Maturity / Q000187:drug effects*; D020567:Fetal Weight / Q000187:drug effects; D008168:Lung / Q000196:embryology*; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D011663:Pulmonary Surfactants / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012756:Sheep
chemical_list: D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D015060:1,2-Dipalmitoylphosphatidylcholine; D001623:Betamethasone