title: The plasma renin-angiotensin system in preeclampsia: effects of magnesium sulfate.
abstract: Two groups of women were studied in a prospective longitudinal fashion to determine the effects of a 2.5-hour infusion of magnesium sulfate upon the renin-angiotensin system. Serum magnesium concentration, angiotensin-converting enzyme concentration, and plasma renin activity were measured at uniform intervals in women with either preeclampsia or preterm labor. Plasma renin activity was significantly lower (3.9 +/- 2.2 versus 6.1 +/- 1.8 ng/mL/minute; P = .004) and angiotensin-converting enzyme significantly higher (47.1 +/- 14 versus 34.0 +/- 10 U/mL; P = .008) in women with preeclampsia than in those with preterm labor. Magnesium infusion was associated with a sustained decline in plasma renin activity in preeclamptic women (P = .003). A transient decline in angiotensin-converting enzyme (P = .009) was observed in women with preeclampsia, but not with preterm labor. In contrast to the sustained change in plasma renin activity, angiotensin-converting enzyme concentration returned to baseline activity levels by 2.5 hours. A nonsignificant negative relationship (P = .06) was noted between angiotensin-converting enzyme and gestational age in subjects with preeclampsia. We conclude that a short-term infusion of magnesium sulfate leads to a sustained decline in plasma renin activity in preeclamptic women, but exerts no sustained effect on angiotensin-converting enzyme in women with either preeclampsia or preterm labor.
authors.affiliation: Perinatal Research Laboratory, University of Iowa College of Medicine, Iowa City.
authors.forename: S L
authors.initials: SL
authors.lastname: Sipes
authors.forename: C P
authors.initials: CP
authors.lastname: Weiner
authors.forename: T M
authors.initials: TM
authors.lastname: Gellhaus
authors.forename: J D
authors.initials: JD
authors.lastname: Goodspeed
mesh_terms: D000328:Adult; D003864:Depression, Chemical; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D007703:Peptidyl-Dipeptidase A / Q000097:blood; D011225:Pre-Eclampsia / Q000097:blood / Q000188:drug therapy*; D011247:Pregnancy; D011446:Prospective Studies; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000187:drug effects*; D013997:Time Factors
chemical_list: D008278:Magnesium Sulfate; D007703:Peptidyl-Dipeptidase A; D012083:Renin