Plasma prostacyclin and thromboxane concentrations in 160 normotensive, hypotensive, and preeclamptic patients during pregnancy, delivery, and the post partum period.

Plasma concentrations of 6-keto-prostaglandin F1 alpha, a stable metabolite of prostacyclin, and TxB2 were measured in 160 women during pregnancy (n = 106), delivery (n = 40), and in the postpartum period (n = 14). Fifty nine patients had normal blood pressure, 10 had mild and 9 severe preeclampsia while 38 patients were hypotensive. Normotensive patients were grouped according to their gestational age: 22-26 weeks (n = 22), 27-31 weeks (n = 22), and 32-38 weeks (n = 15). 20 patients were in early first stage of delivery (cervical dilatation < or = 5 cm), 20 patients in late first stage (cervical dilatation > or = 6 cm). The concentration (mean value +/- SEM) of the PGI2 metabolite tended to increase during pregnancy without reaching significance (218 +/- 11; 225 +/- 10; 250 +/- 15 pg/ml). At the same time, TxB2 showed a decrease, which was most pronounced at 27-31 weeks (65 +/- 15; 40 +/- 2; 48 +/- 4 pg/ml; p < 0.001). The ratio of PGI2/TxA2 increased in parallel (4.9 +/- 0.4; 6 +/- 0.4; 4 +/- 0.5). There was no difference in plasma concentrations of PGI2 (figure 4) and TxA2 in patients with normal blood pressure, mild preeclampsia and hypotension, whereas in severe preeclampsia, the plasma concentration of PGI2 was significantly lower (p < 0.001) and of TxA2 significantly higher (p < 0.001). The ratio of PGI2/TxA2 shifted significantly to vasoconstriction in patients with severe preeclampsia (p < 0.0001) and to vasodilatation in those with hypotension (p < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)