Transmembrane Cation Transport: An Approach to the Study of the Molecular Basis of Hypertension

Mazzanti, Laura; Rabini, R. A.; Cester, N.; Romaninï, Carlo; Bertoli, Enrico

doi:10.1007/978-3-642-74415-0_13

Cited by 2 publications

(1 citation statement)

References 8 publications

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“…The ATPase reaction was started by the addition of 3 mM ATP (sodium salt) and stopped 20 min later by the addition of 1 ml 15% trichloroacetic acid. Inorganic phosphate hydrolyzed from reaction was measured by the method of Fiske and Subbarow [20] as previously described [21,22].…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture

Mazzanti

Rabini

Biagini³

et al. 1992

European Journal of Biochemistry

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The human placenta plays an essential role in embryo development, in particular regulating the transport of ions, nutrients and immunoglobulins from the maternal to the fetal circulation, Trophoblast organization into a syncytial layer involves structural and functional steps that may be monitored and elucidated by in vitro studies. The structural stages by which the syncytial trophoblast is formed are not yet understood. In order to clarify the mechanism of trophoblast development, we studied the morphological characteristics of the syncytial trophoblast formation in culture and the functional changes (transport properties and membrane microviscosity) accompanying the structural modifications.By using both 5-nitroxystearate and 16-nitroxystearate as spin labels, we observed an initial increase in membrane order over 0 -24 h of culture, which can be associated with two events: recovery of cell membranes from trypsin and initial aggregation of cytotrophoblasts. The similar behaviour of the order parameters determined with both probes indicates that membrane order changes both inside and in the outer part of the lipid bilayer. The subsequent decrease in membrane order observed at 36-48 h might be related to the process of cellular fusion.The increase in sodium/potassium pump activity in the first 24 h of culture might be an expression of cell recovery following trypsin treatment. The subsequent decrease might represent an adaptive mechanism by which metabolic energy is mainly used for morphogenetic changes.The human placenta plays an essential role in embryo development, regulating, in particular, the transport of ions, nutrients and immunoglobulins from the maternal to the fetal circulation [ l -51. It also functions as an organ, secreting steroids and hormonal proteins [6].Trophoblast organization into a syncytial layer involves structural and functional steps that may be monitored and elucidated by in vitro studies [7-lo]. The structural stages by which the syncytial trophoblast is formed are not yet fully understood. Some authors believe that the mononucleate cytotrophoblast gives rise to the syncytial trophoblast through a process of differentiation and cellular fusion, while other authors hypothesize that the syncytial trophoblast is organised by means of endomitosis of trophoblast cells [ll -151. In order to clarify the mechanism of this stage of development, we studied the morphological characteristics of syncytial trophoblast formation in culture and the functional

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Section: Scanning Electron Microscopymentioning

confidence: 99%

Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture

Mazzanti

Rabini

Biagini³

et al. 1992

European Journal of Biochemistry

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Morpho-functional modifications of human syncytiotrophoblast plasma membrane during Pregnancy Induced Hypertension

Biagini

Salvolini²,

Pugnaloni³

et al. 1995

Mol Cell Biochem

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A decrease of Na+/K(+)-ATPase activity has been reported in syncytiotrophoblast plasma membrane (SPM) obtained from pregnancy induced hypertensive (PIH) women. The aim of the present work was to verify if the reported modifications in activity are due to a decreased number of enzymatic molecules or to a conformational change of the enzyme itself. Morphological studies were performed in order to better understand the relations between the enzymatic protein and the lipid bilayer. Kinetic studies were also performed. SPM obtained from PIH showed: i) an increased affinity of Na+/K(+)-ATPase for ouabain binding, ii) a significant change in the maximum velocity of the enzyme, iii) a higher distribution factor (DF) of intramembrane particles (IMPs) in the exoplasmic face of the membrane, iv) a decreased mean diameter of IMPs both in the protoplasmic and exoplasmic faces, v) a decreased number of IMPs in the exoplasmic face. In conclusion, a conformational modification seems to be at the basis of the decreased Na+/K(+)-ATPase activity during PIH as suggested by binding, ultrastructural and kinetic data herein reported.

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Transmembrane Cation Transport: An Approach to the Study of the Molecular Basis of Hypertension

Cited by 2 publications

References 8 publications

Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture

Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture

Morpho-functional modifications of human syncytiotrophoblast plasma membrane during Pregnancy Induced Hypertension

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Transmembrane Cation Transport: An Approach to the Study of the Molecular Basis of Hypertension

Cited by 2 publications

References 8 publications

Changes in membrane fluidity and Na+/K+‐ATPase activity during human trophoblast cell culture

Changes in membrane fluidity and Na+/K+‐ATPase activity during human trophoblast cell culture

Morpho-functional modifications of human syncytiotrophoblast plasma membrane during Pregnancy Induced Hypertension

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Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture

Changes in membrane fluidity and Na⁺/K⁺‐ATPase activity during human trophoblast cell culture