Na/K- and Mg-ATPase activity in the placenta and in maternal and cord erythrocytes of pre-eclamptic patients.
Abnormal sodium balance is known to be associated with pre-eclampsia, but no investigations have been conducted concerning the enzyme which regulates active sodium transport at the cellular level. In this study, the enzyme responsible for active sodium transport--Na/K-ATPase and a nonspecific ATPase Mg-ATPase--were assayed in the placenta and in maternal and fetal (cord) erythrocytes of pregnant women with and without pre-eclampsia. Placental ATPase activity was unaffected by pre-eclampsia. However, in infants of pre-eclamptic mothers, fetal erythrocytes were found to have significantly less activity (42 per cent) of both enzymes than fetal erythrocytes from infants of normal mothers. In pre-eclamptic mothers, erythrocyte Mg-atpase activity was significantly less (41 per cent) than normal and Na/K-ATPase activity was slightly decreased (16 per cent). These results indicate that disruption of active sodium transport in fetal erythrocytes is associated with pre-eclampsia and are not inconsistent with the hypothesis of a circulating "toxin."