Platelet-activating factor-acetylhydrolase activity in normotensive and hypertensive pregnancies

Objective: The purpose of our study was to evaluate the hypothesis that pregnancy is associated with decreased platelet-activating factor-acetylhydrolase activity in women with normotension, but not in women with hypertension. Study Design: We evaluated plasma platelet-activating factor-acetylhydrolase activity in normal nonpregnant women (n = 10), normal pregnant women (n = 24), pregnant women with pregnancy-induced hypertension-preeclampsia (n = 7), and a group of men with normotension (n =10). Results: Platelet-activating factor-acetylhydrolase activity was lower at 32 weeks of gestation during normal pregnancies compared with nonpregnant controls (p < 0.001); however, in women with pregnancy-induced hypertension-preeclampsia, platelet-activating factor-acetylhydrolase activity was not decreased. Platelet-activating factor-acetylhydrolase activity in men was higher than in all women (p < 0.01). Conclusion: Pregnant women with normotension may be refractory to pressor agents such as angiotensin II in part because of the decrease in plasma platelet-activating factor-acetylhydrolase activity, which results in an increase in platelet-activating factor. In contrast, enzyme activity is not decreased in pregnant women with hypertension, who have increased sensitivity to various pressor agents.