Increased blood flow resistance in placental circulation and levels of plasminogen activator inhibitors types 1 and 2 in severe preeclampsia.

To study whether increased resistance in the placental circulation changes the plasma levels of plasminogen activators types 1 and 2 (PAI-1 and PAI-2) in severe preeclampsia, the levels of PAI-1 activity and PAI-2 antigen were determined in 33 severely preeclamptic and 22 normal pregnant women during gestational weeks 24-35. In the preeclampsia group, the Pulsatility Index (PI) of the umbilical artery was investigated with Doppler ultrasound. The levels of PAI-1 activity were higher (P < 0.01) whereas those of PAI-2 antigen were lower (P < 0.01) in the preeclampsia group than in the normal pregnancy group. The patients with abnormally high PI (high PI group) had increased PAI-1 levels (P < 0.05) and unchanged PAI-2 levels (P > 0.05), compared with those with normal PI (normal PI group). The levels of PAI-1 were positively correlated to the PI values during pregnancy weeks 34-35 only in the high PI group (r = 0.88, P < 0.05). In conclusion, high resistance in the placental circulation elevates plasma PAI-1 activity levels but does not influence PAI-2 antigen levels.