Pregnancy induced hypertension: a role for peroxidation in microvillus plasma membranes.

It has been recently hypothesized that in PIH a placental oxidant-antioxidant imbalance might cause the release of lipoperoxidation products into the circulation, with subsequent damage of endothelial cell membranes. In this hypothesis the endothelial cell and further increase in circulating lipoperoxide levels, which are by themselves able to induce smooth muscle constriction and increased pressor responsiveness to angiotensin II. In order to investigate this issue, we studied the basal content of lipid peroxides in terms of malondialdehyde (MDA) in the syncytiotrophoblast plasma membranes (SPM) from PIH women.

Na,K-ATPase from placenta of women with pregnancy-induced hypertension exhibits an increased affinity for cardiac glycosides.

Microsomes were prepared from placentas of normotensive women and of patients suffering from pregnancy-induced hypertension (PIH). Activity of Na,K-ATPase (estimated as ATP hydrolysis) from the hypertensive tissue was lower than from tissue of normotensive women, even if the number of Na,K-ATPase molecules (monitored by anthroyl ouabain binding) was actually greater in the hypertensive tissue. The affinity of Na,K-ATPase for anthroyl ouabain was about four times higher in plasma membranes of hypertensives, indicating some structural change in the Na,K-ATPase or in its vicinity.

Local anaesthetic effects on trophoblast membrane fluidity.

Previous studies showed that anaesthesia with the barbiturate Thiopental induces an increase in membrane fluidity and a decrease in acetylcholinesterase activity in syncytiotrophoblast plasma membranes (SPM) obtained from placentas after Cesarean section. The aim of the present work was to compare the effect of a local anaesthetic (bupivacaine hydrochloride, trade name Marcaine) on SPM in vivo and to establish whether the anaesthetic is still present in the membrane after tissue preparation. The acetylcholinesterase activity was lower in Marcaine-anaesthetized SPM (27 +/- 3 against 39 +/- 6 in the control).