Effects of anti-hypertensive drugs on production of soluble fms-like tyrosine kinase 1 and soluble endoglin from human normal and pre-eclamptic placentas in vitro.

1. Increases in soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) contribute to the pathogenesis of pre-eclampsia. Soluble Flt-1 binds to circulating free vascular endothelial growth factor and placenta growth factor and this is associated with endothelial dysfunction. Soluble endoglin, a transforming growth factor (TGF)-beta coreceptor, was reported to synergize with sFlt-1 to amplify endothelial dysfunction by inhibiting TGF-beta1-mediated vasorelaxation. 2. The aim of the present study was to examine whether the antihypertensive drugs clonidine (0.08-1.3 microg/mL), diazoxide (25-300 microg/mL), frusemide (60-1000 microg/mL) and hydralazine (6.3-100 microg/mL) have any effect on placental production of sFlt-1 and sEng in placentas from normal and pre-eclamptic pregnancies. 3. Explants were taken from non-laboured term placentas of normal pregnancy (n = 5) and women with pre-eclampsia (n = 5). Villous explants were cultured with increasing doses of antihypertensive drugs. Placental sFlt-1 and sEng production was examined using ELISA. 4. Baseline sFlt-1 production was higher in placentas from women with pre-eclampsia than from normal pregnancy (4.5 +/- 1.4 vs 3.2 +/- 0.6 ng/mg of total protein, respectively; P < 0.001), as was sEng production (9.0 +/- 2.3 vs 4.1 +/- 0.6 ng/mg of total protein, respectively; P < 0.001). With the exception of frusemide, none of the antihypertensive drugs tested had any effect on sFlt-1 and sEng production from placental explants of normal pregnancy and women with pre-eclampsia. Increasing frusemide concentrations were correlated with increased sEng production in normal pregnancy (P < 0.005). 5. In conclusion, placental sFlt-1 and sEng production was higher in pre-eclampsia and antihypertensive drugs had no effect on placental production of sFlt-1 and sEng in vitro.