1557 PROSTAGLANDIN (PG) SYNTHESIS INHIBITORS AND FETAL BREATHING MOVEMENTS (FBM) IN SHEEP BEFORE DELIVERY

Abstract

In fetal sheep, plasma PGE2 concentrations are high and FBM are intermittent, only in low voltage electrocortical activity (ECoA). Before delivery, as FBM decrease, PGE2 concentrations rise. Meclofenamate, a PG synthesis inhibitor, stimulates FBM even in high voltage ECoA (HVSA), while PGE2 inhibits FBM. Therefore, before delivery, the rise in plasma PGE2 concentration may decrease FBM. To test this hypothesis, we suppressed PG production by continuously infusing Meclofenamate (0.8 mg/kg/h) into 5 fetal sheep (Mec) for 5-13d until delivery (133 to 150d gest). We infused solvent into 4 controls (Con) for 5-lld (131 to 146d gest). Both groups had similar daily pH, PCO2 PO2 and ECoA. Other results are: Though Meclofenamate decreased PGE2 concentrations, both groups had a similar decrease in the incidence of FBM during the two days before delivery. However, Meclofenamate increased the incidence of FBM in HVSA until the day before delivery. We conclude that the decrease in the incidence of FBM before delivery is not dependent on high plasma PGE2 concentrations.