Endothelial function in myometrial resistance arteries of normal pregnant women perfused with syncytiotrophoblast microvillous membranes

Objective To investigate the effects of syncytiotrophoblast microvillous membranes (STBM) in concentrations, found in vivo in women with pre-eclampsia, on endothelial function in isolated resistance arteries.

Setting Department of Obstetrics and Gynaecology, Huddinge University Hospital, Stockholm.

Sample Twenty-nine myometrial resistance arteries isolated from biopsies of healthy term pregnant women, obtained during caesarean section.

Methods The myometrial arteries were mounted in a pressure arteriograph and perfused intraluminally for three hours with STBM (20 to 2000ng/mL) or with erythrocyte membranes or physiological salt solution as controls, all substituted with 0.5% bovine serum albumin. Bradykinin concentration-response curves were performed before and after perfusion.

Main outcome measures The bradykinin concentrationresponse curves were fitted to the Hill equation and maximal dilation and the pEC₅₀ values were determined from these fits. Differences within groups were analysed with a paired Student's t test. Electron microscopic evaluation of the endothelium was performed.

Results Neither STBM nor erythrocyte membrane perfusion affected maximal dilation or the pEC₅₀ values of the bradykinin concentration-response curves at any concentration. Examination by electron microscopy showed no obvious damage to the endothelium after perfusion with STBM or erythrocyte membranes.

Conclusion Perfusion with STBM in concentrations up to 100 times those reported in pre-eclampsia has no significant effect on bradykinin-mediated dilation in isolated myometrial arteries.