Before delivery in fetal sheep tracheal fluid production decreases and surfactant content of lung increases. This occurs as plasma Cortisol and PGE2 concentrations increase. As PGE2 infusions decrease tracheal fluid production and increase cortisol concentration, the increase in PGE2 concentration before delivery may contribute to the above changes. To test this hypothesis, we suppressed PG production by continuously infusing Meclofenamate (0.8 mg/kg/h), a PG synthesis inhibitor, into 5 fetal sheep (Mec) for 5-13d until delivery (133 to 150d gest). We infused solvent into 4 controls (Con) for 5-11d (131 to 146d gest). Both groups had similar daily HR, BP, pH, PO2, and PCO2.
Meclofenamate infusion decreased PGE2 concentration, but in both groups, tracheal fluid production and Cortisol concentration were similar. Surfactant content of lungs of Mec were lower than of Con (P= 0.1). Birthweight and lung weight were the same in both groups. We conclude that normal lung growth and the changes in tracheal fluid production and cortisol concentration before delivery are not dependent on high plasma PGE2 concentrations. (Supported by USPHS HL27356, Pulmonary SCOR, and ALA fellowship.)