Inhibitors of prostaglandin synthesis, tracheal fluid, and surfactant in fetal lambs.
To study their effects on tracheal fluid (TF) production and surfactant flux, we gave 12-h infusions of prostaglandin synthetase inhibitors (PGSI) on 16 occasions to 10 fetal lambs at gestational ages (GA) of 125--141 days. Results were similar with both sodium meclofenamate (13.9 +/- 3.4 mg.kg-1, 12 studies) and indomethacin (33.6 +/- 8.0 mg.kg-1, 4 studies). All studies were done at least 6 days after surgery and 4 days before spontaneous birth. During infusions of PGSI, there were no changes in fetal arterial blood pressure, pH, PaO2, PaCO2, TF production or its concentration of sodium, potassium, and chloride; calcium concentration in TF increased slightly. We expressed tracheal surfactant flux as micrograms.kg-1.h-1 of saturated phosphatidylcholine (SPC). If control SPC flux was less than 5 micrograms.kg-1.h-1 (10 studies at GA of 125--141 days), it did not change during infusion of PGSI; however, if control was greater than 5 micrograms.kg-1.h-1 (6 studies at GA 132--140 days), SPC flux decreased during the infusions in all studies. The results suggest that prostaglandins do not strongly influence TF production up to 4 days before birth and that prostaglandins are involved in the increased flux of surfactant which occurs in late gestation.
D000818:Animals; D001826:Body Fluids / Q000187:drug effects; D005260:Female; D006863:Hydrogen-Ion Concentration; D007213:Indomethacin / Q000494:pharmacology; D008168:Lung / Q000196:embryology*; D010100:Oxygen / Q000097:blood; D010713:Phosphatidylcholines / Q000097:blood; D011247:Pregnancy; D011453:Prostaglandins / Q000096:biosynthesis*; D011663:Pulmonary Surfactants / Q000378:metabolism*; D012756:Sheep; D014132:Trachea / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism
D010713:Phosphatidylcholines; D011453:Prostaglandins; D011663:Pulmonary Surfactants; D010100:Oxygen; D007213:Indomethacin