Membrane, intracellular, and plasma magnesium and calcium concentrations in preeclampsia.
ABSTRACT Changes in intracellular calcium and magnesium concentrations seem to be involved in the pathogenesis of preeclampsia, whereas the role of cell membranes has not been studied in detail yet. To investigate the changes in calcium and magnesium metabolism in normal pregnancy and preeclampsia, plasma, intracellular, and membrane calcium and magnesium concentrations were determined in a clinical study. Twenty-five control, 18 untreated healthy pregnant, and 16 nulliparas preeclamptic women were investigated. Plasma, cellular, and membrane (erythrocytes) calcium and magnesium contents were measured by atomic absorption spectroscopy. Plasma and intracellular magnesium concentrations were significantly lower in the healthy pregnant group and the preeclamptic group as compared to controls (P < .01). In erythrocyte membranes magnesium content was found significantly decreased in the preeclamptic women as compared to healthy subjects (P < .001). There was a significant decrease in the plasma calcium concentration in the preeclamptic group compared to controls or healthy pregnant women (P < .05). Membranous calcium content was significantly increased in the preeclamptic group versus controls or healthy pregnant women (P < .001) and an inverse correlation with membranous magnesium content was found (r = -0.79,P < .01). Lowered plasma, intracellular, and membrane magnesium concentrations in preeclampsia may contribute to the development in hypertension in pregnancy. In addition, a disturbed calcium homeostasis is observed in preeclampsia.
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ABSTRACT: Objectives High blood pressure during the last part of pregnancy is a risk indicator of pre-eclampsia and eclampsia which augment infant and maternal morbidity and mortality. Magnesium deficiency has been related to the risk of hypertension. A study was performed to assess the relation between pregnancy induced hypertension, excretion of urinary magnesium and expression of magnesium sensitive genes (MgSG). Methods A cohort of healthy, nulliparous women with singleton pregnancies was recruited. Blood pressure was recorded throughout pregnancy. Urinary magnesium excretion and expression of MgSGs in leukocytes were determined. Results The expression of the gene TRPM6 was higher among pregnant women compared to non-pregnant controls at week 12. All other genes had lower expressions in pregnant women. At week 37 the expressions of all genes were lower than at week 12. The expressions of SLC41A1, SLC41A3, and TRPM7 were related to the systolic and diastolic blood pressures. Furthermore, the expression of TRPM6 was related to the urinary excretion of magnesium and the change in diastolic blood pressure weeks 12–37 was inversely related to the change in magnesium excretion. Conclusions Systolic and diastolic blood pressure and the excretion of magnesium during pregnancy were related to the expression of different MgSGs. The results suggest that magnesium is involved in the regulation of blood pressure during pregnancy.Pregnancy Hypertension: An International Journal of Women's Cardiovascular Health. 01/2013;
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ABSTRACT: The populations of many species of sub-Arctic animals have recently ceased to fluctuate cyclically. The ultimate cause of this would seem to be changes in the weather, and the proximate cause has been credited to less winter snow allowing predators better access to their prey, thus enabling them to prevent surges in the prey's abundance. But there is evidence that this is not so; that, rather, the numbers of predators are limited by the abundance of their prey. Furthermore, there is alternative evidence that suggests that changes in the cyclical availability of food, brought about by changing weather conditions, may be dampening fluctuations in the abundance of these populations. On the wider ecological front, the evidence presented here further supports the commonality of how a shortage of food of a quality that can support breeding, not the action of predators, generally limits the abundance of populations of both prey and predator.ZusammenfassungDie Populationen vieler subarktischer Tierarten haben in neuerer Zeit aufgehört zyklisch zu fluktuieren. Der ultimate Grund hierfür scheinen Änderungen der Witterung zu sein, während der proximate Grund geringerem Schneefall im Winter zugeschrieben worden ist, der den Räubern besseren Zugang zu ihrer Beute erlaubt und sie damit befähigt, starke Zunahmen der Beutepopulationen zu verhindern.Es gibt indessen Anhaltspunkte dafür, dass dies nicht so ist, dass vielmehr die Zahl der Räuber durch die Abundanz der Beutetiere limitiert wird. Darüber hinaus gibt es weitere Indizien, die nahelegen, dass Änderungen in der zyklischen Verfügbarkeit der Nahrung, hervorgerufen durch gewandelte Witterungsbedingungen, die Abundanzfluktuationen dieser Populationen dämpfen können. Auf dem weiteren ökologischen Feld unterstützen die hier präsentierten Belege ein gemeinsames Muster, nämlich wie der Mangel an Nahrung einer Qualität, die die Aufzucht von Nachkommen ermöglicht, -und nicht die Einwirkung von Räubern- generell die Abundanzen von Beute- und Räuberpopulationen limitiert.Basic and Applied Ecology 09/2011; 12(6):481–487. · 2.39 Impact Factor
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ABSTRACT: In the current study the possible relationship between the Ca(2+)/Mg(2+) ratio of human syncytiotrophoblast plasma membranes and their lipid peroxidation and Ca(2+)-ATPase activity was determined. Syncytiotrophoblast plasma membranes of placental explants cultured under hypoxia increased their lipid peroxidation and Ca(2+) content, diminished their Ca(2+)-ATPase activity, and kept their Mg(2+) content unchanged. Membranes preincubated with different concentrations of Ca(2+) increased their Ca(2+) content without changes in their Mg(2+) content. There is a direct relationship between Ca(2+) content and lipid peroxidation of the membranes, as well as an inverse relationship between their Ca(2+) content and Ca(2+)-ATPase activity. On the contrary, preincubation of membranes with different concentrations of Mg(2+) showed a higher Mg(2+) content without changing their lipid peroxidation and Ca(2+)-ATPase activity. Explants cultured under hypoxia in the presence of 4 mM MgSO4 showed similar values of lipid peroxidation and Ca(2+)-ATPase activity of their membranes compared to those of explants cultured under normoxia. Increased Ca(2+) 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. Mg(2+) might exert a stabilizing effect of the membranes, avoiding their exposure to free radicals.BioMed Research International 01/2014; 2014:597357. · 2.71 Impact Factor