Relation between umbilical prostacyclin production and blood-flow in the fetus.

Umbilical blood-flow (UBF) was measured by ultrasonography in 28 pregnant women. A superfusion preparation was used to investigate the production of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a breakdown product of prostacyclin (PGI2) and thromboxane B2 (TxB2), a breakdown product of TxA2, by specimens from the umbilical arteries of the infants born to these 28 mothers and those born to 36 other women in whom UBF had not been measured. UBF was significantly related to 6-keto-PGF1 alpha production. 6-keto-PGF1 alpha production was lower in infants of the 8 pre-eclamptic mothers (14.5 ng min-1 g-1) than in those of 45 healthy mothers (26.9 ng min-1 g-1). Generation of TxA2 by the umbilical artery was 15-25 times less than that of 6-keto-PGF1 alpha, and TxA2 concentrations were unrelated to UBF or the type of pregnancy. These data provide the first evidence for a direct association between blood-flow and PGI2 generation in human vasculature.