Effects of indomethacin on the acid-base balance and hemodynamics of chronically instrumented pregnant sheep.

Maternal and fetal responses to maternal intravenous administrations of indomethacin (0.5 mg/kg over 3 min) were evaluated in 10 experiments performed on 6 ewes at gestational ages of 107-139 days. Maternal and fetal aortic blood samples were obtained at frequent intervals over 2 h from the start of infusion. Significant maternal effects were (1) an increase in blood pressure (5 min) and (2) a decrease in heart rate (5, 15, 30 min). Fetal effects included (1) an increase in pH (5, 15 min) and (2) tachycardia (45, 60, 90, 120 min). At the dosage and duration administered, these maternal and fetal hemodynamic and fetal acid-base changes occurred independently of any effect upon uterine blood flow.