Nitric oxide activity in the peripheral vasculature during normotensive and preeclamptic pregnancy

• Published in: American journal of physiology. Heart and circulatory physiology 1999-08, Vol.277 (2), p.H848-H854
• Main Authors: Anumba, Dilly O. C, Robson, Stephen C, Boys, Richard J, Ford, Gary A
• Format: Article
• Language: English
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.1999.277.2.h848

Departments of 1  Obstetrics and Gynaecology, 2  Statistics, 3  Medicine, and 4  Pharmacological Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 4LP, United Kingdom We investigated the role of nitric oxide (NO) in the vascular resistance changes of normotensive and preeclamptic pregnancy. Forearm blood flow (FBF) responses to brachial artery infusion of N G -monomethyl- L -arginine ( L -NMMA), an NO synthase inhibitor, and angiotensin II (ANG II), an NO-independent vasoconstrictor, were determined by plethysmography in 20 nonpregnant women, 20 normotensive primigravidae, and 15 primigravidae with untreated preeclampsia. In pregnant subjects, FBF was reduced to nonpregnancy levels by infusion of norepinephrine (NE), which was then coinfused with ANG II (2, 4, and 8 ng/min) and L -NMMA (200, 400, and 800 µg/min) each for 5 min. In separate studies, responses to NE (20, 50,   and 100 ng/min) were determined in 8 nonpregnant women, with FBF elevated to pregnancy levels by concomitant infusion of glyceryl trinitrate, and 10 pregnant women. Vasoconstrictor responses to L -NMMA were increased in pregnant compared with nonpregnant subjects [mean ± SE summary measure (in arbitrary units): 60 ± 7 vs. 89   ± 8, respectively; P