Toggle Main Menu Toggle Search

Open Access padlockePrints

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

Lookup NU author(s): Professor Steve RobsonORCiD, Professor Gary Ford


Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


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 mu g/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 tin arbitrary units): 60 +/- 7 vs. 89 +/- 8, respectively; P < 0.01], whereas responses to ANG II were blunted (125 +/- 11 vs. 79 +/- 7, respectively; P < 0.001). Compared with normotensive pregnant subjects, preeclamptic subjects had an enhanced response to ANG 11 (79 +/- 7 vs. 103 +/- 8, respectively; P < 0.05) but no difference in response to L-NMMA (89 +/- 8 vs. 73 +/- 10, respectively; P = 0.30). Responses to NE were similar in pregnant and nonpregnant subjects (110 +/- 20 vs. 95 +/- 33, respectively; P = 0.66). During the third trimester of pregnancy, forearm constrictor responses to L-NMMA are increased. The responses to NE are unchanged, whereas responses to ANG II are blunted. Increased NO activity contributes to the fall in peripheral resistance. In preeclampsia, forearm constrictor responses to ANG II but; not L-NMMA are increased compared with those in normal pregnancy. Changes in vascular NO activity are unlikely to account for the increased vascular tone in this condition.

Publication metadata

Author(s): Robson SC; Ford GA; Anumba DOC; Boys RJ

Publication type: Article

Publication status: Published

Journal: American Journal of Physiology: Heart and Circulatory Physiology

Year: 1999

Volume: 277

Issue: 2

Pages: H848-H854

Print publication date: 01/08/1999

ISSN (print): 0363-6135

ISSN (electronic):

Publisher: American Physiological Society