Na⁺, K⁺-ATPase and Ca²⁺-ATPase activities in basal and microvillous syncytiotrophoblast membranes from preeclamptic human term placenta

Abstract

Objective: The aim of this study is to evaluate the effect of preeclampsia on the level of lipid peroxidation, activity and expression of both plasma membrane Ca²⁺- and Na⁺, K⁺-ATPases in syncytiotrophoblast. Methods: The level of lipid peroxidation was estimated by measuring TBARS. ATPase activities were quantified by a colorimetric method measuring the amount of inorganic phosphate during the assay. Expression of Ca²⁺- and Na⁺, K⁺-ATPases in syncytiotrophoblast plasma membranes and term placenta tissue sections was investigated using Western blot and immunohistochemistry, respectively. Results: Our results show a higher level of lipid peroxidation of syncytiotrophoblast plasma membranes from preeclamptic, as compared to uncomplicated pregnant women. Preeclampsia also significantly reduced the activity of Ca²⁺- and Na⁺, K⁺-ATPases; however, expression of both ATPases was unaffected. Conclusion: Our findings suggest that the reduction of Ca²⁺- and Na⁺, K⁺-ATPase activities during preeclampsia could be at least partially due to an increased level of lipid peroxidation of the syncytiotrophoblast plasma membranes.

• Ca²⁺-ATPase
• Na⁺, K⁺-ATPase
• Preeclampsia
• Placenta
• Syncytiotrophoblast

ACKNOWLEDGEMENTS

We are grateful to Dr. M. Pérez and the staff of the San José Hospital Maternity Unit for assistance in obtaining the biological material. Purified bovine brain calmodulin was generously supplied by Dr. Gustavo Benaim from the Universidad Central de Venezuela.

DECLARATION OF INTEREST

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This research was supported in part by grant from Fondecyt, Chile No. 1070695, by grant no. H9/181/R427, Project 96350, from the World Health Organization and by grant from FONACIT, Venezuela No. F-2005000222.