Nifedipine reduces pressor responsiveness to angiotensin II in pregnant women

Abstract

Objective: We assessed the action of nifedipine on vascular reactivity to angiotensin II (AII) in pregnant women at risk for hypertension.

Methods: We studied eleven pregnant women (28-32 weeks' gestation) who had shown a 20 mmHg increase in basal diastolic blood pressure at AII infusion rates < 10 ng/kg/min (Effective pressor dose, EPD), and were therefore considered at high risk for the subsequent development of pregnancy-induced hypertension, according to Gant. After the AII infusion was completed, we allowed the patients 4 hours of rest to avoid interactions with the first test, then administered 10 mg nifedipine, and after 30 minutes repeated the test.

Results: In all the 11 women the EPD after nifedipine administration had significantly reverted to normal (paired t-test: p < 0.03).

Conclusions: The efficacy of nifedipine in reducing the pressor response to AII suggests the involvement of intracellular free calcium in the vascular response to pressor agents in pregnancy, and supports the use of this drug in the treatment of pregnancy-induced hypertension.