Angiotensin-converting enzyme activity in hypertensive subjects after magnesium sulfate therapy.

Angiotensin-converting enzyme is a peptidase involved in the formation of angiotensin II and the inactivation of bradykinin. In a previous study we found elevated angiotensin-converting enzyme activity in women with pregnancy-induced hypertension prior to magnesium sulfate therapy and lower levels during therapy. This prospective study was undertaken in order to determine if angiotensin-converting enzyme activity indeed decreased after magnesium sulfate therapy. Sixteen patients with pregnancy-induced hypertension were studied before and during magnesium sulfate therapy. Angiotensin-converting enzyme activity was found to decrease 1 to 8 hours into therapy and then plateau between 9 and 24 hours. Possible mechanisms for this observation are discussed.