Immunoreactive prostacyclin and thromboxane metabolites in normal pregnancy and the puerperium

Abstract

Prostacyclin and thromboxane have been implicated in the pathophysiology of several disorders of pregnancy, but there is little information on concentrations of these prostaglandins in normal pregnancy. The aim of our study was to determine the range of values throughout normal pregnancy and the puerperium and to compare this with concentrations in normal non-pregnant women. Measurement was by radioimmunoassay of prostacyclin and thromboxane metabolites. We observed a significant difference in prostacyclin metabolites in the first trimester. (mean 19.9, §EM 0.96 pg/ml) compared with the normal non-pregnant group (mean 15.9. SEM 0.68 pgh1). There were no significant differences between values in the normal non-pregnant group and those in the second and third trimester or postnatally. The increase in prostacyclin in the first trimester may be associated with placent a t' ion and physiological vasodilation, and insencitivity to angiotensin 11 5een in early pregnancy. We noted a significant redaction in thromboxane metabolites in the second (mean 133, SEhl 14.9 pgirnl) and third (mean 123, SEM 30.7 pgiml) trimesters and the puerperium (mean 119, SEM 6.3 pgiml) compared with the values in the normal non-pregnant group (mean 142, SEM4.9pgiml). This may be due to increased platelet stability or decreased thromboxane synthesis. 20, 105-110. 389-399.

Thromboxane A2 and prostacyclin levels in molar pregnancy

“…In all the normal patients amniotic fluid PGI, metabolities were undetectable whereas the normal maternal plasma level was 15.8 (SEM 0.7) pgiml, this compares with our previously reported mean level of 15.5 (SEM 1.05) pgiml for normal second trimester pregnancy (Greer et al 1985). In the one abnormal pregnancy, however, amniotic fluid PGI, metabolites were 62 pgiml and the maternal plasma level was 170 pg!nil, the highest we have ever recorded in pregnancy.…”

“…All patients were undergoing amniocentesis for genetic analysis or investigations for a possible neural-tube defect. We used a RIA previously described (Belch et al 1983;Greer et al 1985) with a lower limit of sensitivity of 5 pgiml, interand intra-assay variations were both less than 10% and recovery of added 6-keto-PGF,,was 95 (SD 9)%.…”

“…All patients were undergoing amniocentesis for genetic analysis or investigations for a possible neural-tube defect. We used a RIA previously described (Belch et al 1983;Greer et al 1985) with a lower limit of sensitivity of 5 pgiml, interand intra-assay variations were both less than 10% and recovery of added 6-keto-PGF,,was 95 (SD 9)%.Of the 27 pr_egnancies 26 were normal and in one the fetus had a myelomeningocoele. In all the normal patients amniotic fluid PGI, metabolities were undetectable whereas the normal maternal plasma level was 15.8 (SEM 0.7) pgiml, this compares with our previously reported mean level of 15.5 (SEM 1.05) pgiml for normal second trimester pregnancy (Greer et al 1985).…”

Matrix Metalloproteinases as Drug Targets in Preeclampsia

“…These hormones interact with the the renin-angiotensin-aldosterone system (RAAS) [29] and the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway to control blood pressure during pregnancy [30]. Studies in humans and pregnant models have implicated NO [31, 32] and prostacyclin [33, 34] as key vasodilators responsible for the reduced vascular resistance seen in pregnancy [35]. Another important mechanism contributing for the systemic vasodilatation is a decreased vascular responsiveness to angiotensin II [36].…”

Diabetes and the maternal resistance vasculature

“…One possibility may be alterations in signal transduction pathways [84], which may account for the reduction of pressor responses to various vasoconstrictor agonists [85,86]. The increased synthesis and release of various endothelium-dependent relaxing factors, such as NO and PGI # [87,88], a decrease in the number of adrenergic receptors and a blunting of reflex cardiac responses [89,90] have also been implicated.…”