| dc.description | Plasma membrane Ca2+-ATPase activity diminishes by about 50% in red blood cells during preeclampsia. We investigated whether the number
of Ca2+-ATPase molecules is modified in red cell membranes from preeclamptic pregnant women by measuring the specific phosphorylated
intermediate of this enzyme. Also, we isolated the Ca2+-ATPase protein from both normotensive and preeclamptic pregnant women and estimated
its molecular weight, and its cross-reactions with specific polyclonal and monoclonal (5F10) antibodies against it. We measured the Ca2+-ATPase
activity in a purified state and the effect of known modulators of this ATPase. It was found that the phosphorylated intermediate associated with
PMCA is similar for red cell ghosts from normotensive and preeclamptic women, suggesting a similar number of ATPase molecules in these
membranes. The molecular weight of the Ca2+-ATPase is around 140 kDa for both normotensive and preeclamptic membranes, and its crossreactions
with specific antibodies is similar, suggesting that the protein structure remains intact in preeclampsia. Calmodulin, ethanol, or both
calmodulin plus ethanol, stimulated the Ca2+-ATPase activity to the same extent for both normotensive and preeclamptic preparations. Our results
showed that the reduced Ca2+-ATPase activity of the red cell membranes from preeclamptic women is not associated with a defective enzyme, but
rather with a high level of lipid peroxidation. | |
