Vasopressor activity in incubated plasma of normal and hypertensive pregnant women

The pressor activity generated in incubated plasma of nonpregnant, normal pregnant, and hypertensive pregnant women was measured by means of a sensitive bioassay technique. It was found that the plasma of normal pregnant women generated significantly higher amounts of active pressor principle than the plasma of nonpregnant women. The plasma of hypertensive pregnant women generated significantly lower amounts of active pressor principle than the plasma of normal pregnant women. Plasma obtained from the antecubital vein revealed no difference in pressor activity compared to plasma collected from the uterine vein at the time of cesarean section. These data suggest that active pressor principle is not involved in the pathogenesis of pregnancy-induced hypertension and that the pregnant uterus is not the source of active pressor principle.