Comparative Study of the Calcium Adenosine Triphosphatase of Basal Membranes of Human Placental Trophoblasts from Normotensive and Preeclamptic Pregnant Women

The Ca-ATPase activity of plasma membranes from human trophoblast is diminished in about 50% in preeclamptic women, as compared to normotensive pregnant women. This diminution is not due to changes in the behavior of the enzyme towards the free calcium concentration, the pH or the temperature of the incubation medium. Neither does it appear to be due to the presence of some condensing factor in the membranes, since the apparent energies of activation for the two tested ranges of temperature (10-20 and 20-37 degrees C) are similar for both normotensive and preeclamptic patients. The possibility of a diminution in the turnover rate of the Ca-ATPase in the plasma membranes from the preeclamptic patients is considered.