Alteration in ouabain-sensitive sodium potassium pump of erythrocytes during pregnancy induced hypertension: a kinetic study.

The erythrocytes are widely used as model cells for studies of sodium-potassium pump (Na(+)-K(+) pump) in health and disease. Hence, to explore the possible role of the Na(+) transport across the cell membrane in the pathogenesis of pregnancy-induced hypertension (PIH), the present study was conducted to assess the Na(+)-K(+) pump functions in relation to its intrinsic kinetic properties using erythrocytes (RBC). Erythrocyte sodium concentration in pregnancy-induced hypertensive women was significantly (p<0.01) lower in comparison to normotensive pregnant women. On the contrary erythrocyte potassium was significantly higher (p<0.01) in PIH women as compared to normotensive pregnant women. Observed alterations in Na(+) and K(+) concentrations in erythrocytes were associated with significantly (p<001) increased Ouabain-sensitive sodium efflux rate and rate constants in erythrocytes from PIH women. Further, kinetic studies revealed that increased Ouabain-sensitive efflux rate constant in RBC from PIH women was accompanied by increased maximal velocity (V(max)) of Na(+)-K(+) pump. However, the affinity constant (K(m)) was unaltered in both the groups. Therefore, these findings suggest that increased Na(+)-K(+) pump activity in RBC of PIH women could be due to either increased numbers of Na(+)-K(+) pump units of increased numbers of active subunits of Na(+)-K(+) pump possibly due to specific plasma factors in PIH women.