PROTECTIVE EFFECTS OF PROSTAGLANDIN E(2) ON THE PARAQUAT-INDUCED CONSTRICTION OF THE FETAL DUCTUS-ARTERIOSUS IN THE RAT

Pregnant rats on day 21 of gestation received a subcutaneous injection of paraquat (25 mg/kg). Two hr later, some fetuses of these rats rece ived a subcutaneous injection of prostaglandin E(2) (PGE(2)). The cali ber of the ductus arteriosus (DA) of fetuses was measured 1 hr later. The DA of fetuses of paraquat-treated pregnant rats was significantly constricted compared with that of fetuses of control pregnant rats giv en physiological saline. However, the DA of PGE(2)-treated fetuses of paraquat-treated pregnant rats had a caliber comparable to that of con trol rats. The maternal plasma PGE(2) level decreased following paraqu at treatment. These results suggest that the decrease of maternal PGE( 2) level results in a constriction of the DA of fetuses.