Effect of Hypoxia on the Calcium and Magnesium Content, Lipid Peroxidation Level, and Ca²⁺-ATPase Activity of Syncytiotrophoblast Plasma Membranes from Placental Explants

Abstract

In the current study the possible relationship between the Ca2+/Mg2+ ratio of human syncytiotrophoblast plasma membranes and their lipid peroxidation and Ca2+-ATPase activity was determined. Syncytiotrophoblast plasma membranes of placental explants cultured under hypoxia increased their lipid peroxidation and Ca2+ content, diminished their Ca2+-ATPase activity, and kept their Mg2+ content unchanged. Membranes preincubated with different concentrations of Ca2+ increased their Ca2+ content without changes in their Mg2+ content. There is a direct relationship between Ca2+ content and lipid peroxidation of the membranes, as well as an inverse relationship between their Ca2+ content and Ca2+-ATPase activity. On the contrary, preincubation of membranes with different concentrations of Mg2+ showed a higher Mg2+ content without changing their lipid peroxidation and Ca2+-ATPase activity. Explants cultured under hypoxia in the presence of 4 mM MgSO4 showed similar values of lipid peroxidation and Ca2+-ATPase activity of their membranes compared to those of explants cultured under normoxia. Increased Ca2+ content of the membranes by interacting with negatively charged phospholipids could result in destabilizing effects of the membrane structure, exposing hydrocarbon chains of fatty acids to the action of free radicals. Mg2+ might exert a stabilizing effect of the membranes, avoiding their exposure to free radicals.

Magnesium sulfate against oxidative damage of membrane lipids: A theoretical model

“…Therefore, these results suggest that MgSO 4 components are mainly adsorbed on the hydrophilic part of the surface membrane. This agrees with the experimental findings of Chiarello et al The authors proposed that magnesium might exert a stabilizing effect on the membrane, avoiding their exposure to free radicals. In this sense, the results of WDD for POPC, MgSO 4 , and • OH show a similar picture to the sum of the separated systems.…”

“…Applications of magnesium sulfate for studying the antioxidant effect against LPO have been the object of study in several research articles . Maulik et al found that guinea pig brain cells under hypoxic conditions have increased LPO and that post‐treatment hypoxia with MgSO 4 reverses these effects.…”

“…However, despite this evidence, the decrease and reduction of • OH radicals due to MgSO 4 is not well understood, and its action mechanism at the molecular level remains an enigma. Chiarello et al proposed that Mg 2+ ions might have a stabilizing effect on syncytiotrophoblast plasma membranes from human placental explants, protecting them against damage from exposure to free radicals. Abad et al suggested that MgSO 4 may provide protection against oxidative damage to the plasma membranes.…”

Changes in calcium channel proteins according to magnesium sulfate administration in placentas from pregnancies with pre-eclampsia or fetal growth restriction

“…We observed that MgSO 4 treatment increased expression of both PMCA and SERCA-2 in BeWo cells. Chiarello et al insisted that MgSO 4 treatment in normal placental explants stabilized the Ca 2+ concentration with an increase in Mg 2+ concentration, and its treatment under hypoxic conditions decreased lipid peroxidation levels with an increase in PMCA activity eventually protecting the ST 22. In our study, however, MgSO 4 treatment under CoCl 2 treatment could not significantly increase PMCA expression, and it even decreased SECA-2 expression in BeWo cells.…”

Apolipoprotein D Overexpression Protects Against Kainate-Induced Neurotoxicity in Mice

“…However, the mechanism by which apoD influences PMCA-2 levels remains to be determined. As the increase of intracellular Ca 2+ content by excitotoxicity stimulates the generation of reactive oxygen species [77] and lipid peroxidation, which in turn downregulates rapidly PMCA levels [78], it is possible that apoD affects PMCA-2 levels through its anti-oxidant properties. Indeed, apoD and its orthologs have been shown to protect from pro-oxidative insults in several organisms [17][18][19]22].…”