[Prostacyclin and thromboxane A2 in umbilical circulation in relation to preeclampsia]

In the present study, metabolites of prostacyclin (PGI2) and thromboxane A2 (TxA2), 6-oxoprostaglandin F1 alpha (PGF1 alpha) and thromboxane B2 (TxB2) in the umbilical circulation were determined. Also the baseline and substrate stimulated synthesis and release of these compounds in the umbilical vessels were measured. Umbilical serum 6-oxo-PGF1 alpha levels were significantly higher while no consistent pattern was found for TxB2. The 6-oxo-PGF1 alpha levels in the umbilical artery (UA) were revealed to be significantly lower in preeclamptic patients (PRC) while TxB2 levels were higher. These levels in the umbilical veins (UV) showed no difference. The base line release of 6-oxo-PGF1 alpha and TxB2 from UA and UV showed no statistical difference. With a saturating dose of sodium arachidonate (A . A), both UA and UV tissue showed marked enhancement in the release of the two, in which 6-oxo-PGF1 alpha from UV was significantly higher than that from UA while TxB2 was without statistical difference. Between normal subjects and PRC, there was no difference in the base line release of 6-oxo-PGF1 alpha from UA, while TxB2 was higher in PRC. Substrate A . A did not enhance the release of 6-oxo-PGF1 alpha in the PRC, but the mean TxB2 release tended to increase both in the control and PRC. Present data indicate that the impaired metabolism, especially that of TxA2, and an imbalance between PGI2 and TxA2 may be involved in the development of PRC.