title: Surfactant phosphatidylcholine half-life and pool size measurements in premature baboons developing bronchopulmonary dysplasia.
abstract: Because minimal information is available about surfactant metabolism in bronchopulmonary dysplasia, we measured half-lives and pool sizes of surfactant phosphatidylcholine in very preterm baboons recovering from respiratory distress syndrome and developing bronchopulmonary dysplasia, using stable isotopes, radioactive isotopes, and direct pool size measurements. Eight ventilated premature baboons received (2)H-DPPC (dipalmitoyl phosphatidylcholine) on d 5 of life, and radioactive (14)C-DPPC with a treatment dose of surfactant on d 8. After 14 d, lung pool sizes of saturated phosphatidylcholine were measured. Half-life of (2)H-DPPC (d 5) in tracheal aspirates was 28 +/- 4 h (mean +/- SEM). Half-life of radioactive DPPC (d 8) was 35 +/- 4 h. Saturated phosphatidylcholine pool size measured with stable isotopes on d 5 was 129 +/- 14 micro mol/kg, and 123 +/- 11 micro mol/kg on d 14 at autopsy. Half-lives were comparable to those obtained at d 0 and d 6 in our previous baboon studies. We conclude that surfactant metabolism does not change during the early development of bronchopulmonary dysplasia, more specifically, the metabolism of exogenous surfactant on d 8 is similar to that on the day of birth. Surfactant pool size is low at birth, increases after surfactant therapy, and is kept constant during the first 2 wk of life by endogenous surfactant synthesis. Measurements with stable isotopes are comparable to measurements with radioactive tracers and measurements at autopsy.
authors.affiliation: Department of Pediatrics/Neonatology, Sophia's Children's Hospital/Erasmus University Rotterdam, Rotterdam, The Netherlands.
authors.forename: Daphne J M T
authors.initials: DJ
authors.lastname: Janssen
authors.forename: Virgilio P
authors.initials: VP
authors.lastname: Carnielli
authors.forename: Paola E
authors.initials: PE
authors.lastname: Cogo
authors.forename: Steven R
authors.initials: SR
authors.lastname: Seidner
authors.forename: Ingrid H I
authors.initials: IH
authors.lastname: Luijendijk
authors.forename: J L Darcos
authors.initials: JL
authors.lastname: Wattimena
authors.forename: Alan H
authors.initials: AH
authors.lastname: Jobe
authors.forename: Luc J I
authors.initials: LJ
authors.lastname: Zimmermann
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000493:pharmacokinetics*; D000818:Animals; D000831:Animals, Newborn; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D001997:Bronchopulmonary Dysplasia / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D003289:Convalescence; D003903:Deuterium / Q000493:pharmacokinetics; D005260:Female; D006207:Half-Life; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000378:metabolism*; D008297:Male; D010215:Papio; D011663:Pulmonary Surfactants / Q000378:metabolism* / Q000627:therapeutic use; D012127:Respiratory Distress Syndrome, Newborn / Q000378:metabolism / Q000628:therapy; D014132:Trachea
chemical_list: D002250:Carbon Radioisotopes; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine; D003903:Deuterium