This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Greenwood, J. P. Articles by Mary, D. A.S.G. Search for Related Content PubMed PubMed Citation Articles by Greenwood, J. P. Articles by Mary, D. A.S.G. Pubmed/NCBI databases Medline Plus Health Information High Blood Pressure High Risk Pregnancy Related Collections Other hypertension Autonomic, reflex, and neurohumoral control of circulation

(Circulation. 2001;104:2200.)
© 2001 American Heart Association, Inc.

Clinical Investigation and Reports

Sympathetic Neural Mechanisms in Normal and Hypertensive Pregnancy in Humans

John P. Greenwood, MB ChB, PhD; Eleanor M. Scott, BM BS, MD; John B. Stoker, BSc, MB ChB; James J. Walker, MB ChB, MD; David A.S.G. Mary, MB ChB, PhD

Departments of Cardiology and Obstetrics and Gynecology (J.J.W.), St James’s University Hospital, Leeds, UK.

Correspondence to Dr J.P. Greenwood, Department of Cardiology, St James’s University Hospital, Beckett St, Leeds, LS9 7TF UK. E-mail john_greenwood{at}hotmail.com

Background— Direct recordings from peripheral sympathetic nerves have shown an increased sympathetic drive in pregnancy-induced hypertension (PIH) and preeclampsia (PE). It is unknown whether sympathetic drive is altered in normal pregnancy, when arterial blood pressure can be normal or relatively low. The aim of this study was to measure and compare peripheral sympathetic discharge, its vasoconstrictor effect and its baroreceptor control, during pregnancy and postpartum in women with normal pregnancy (NP) and PIH and in normotensive nonpregnant (NN) women.

Methods and Results— Twenty-one women with NP, 18 women with PIH, and 21 NN women had muscle sympathetic nerve activity assessed from multiunit discharges (MSNA) and from single units with defined vasoconstrictor properties (s-MSNA). The s-MSNA in NP (38±6.6 impulses/100 beats) was greater (P<0.05) than in NN women (19±1.8 impulses/100 beats) despite similar age and body weight but less than in PIH women (P<0.001) (146±23.5 impulses/100 beats). MSNA followed a similar trend. Cardiac baroreceptor reflex sensitivity (BRS) was impaired in NP and PIH women relative to NN. After delivery, sympathetic activity decreased to values similar to those obtained in NN, and there was an increase in BRS. In women with NP, the decrease in sympathetic output occurred despite an insignificant change in blood pressure.

Conclusions— Central sympathetic output was increased in women with normal pregnancy and was even greater in the hypertensive pregnant group. The findings suggest that the moderate sympathetic hyperactivity during the latter months of normal pregnancy may help to return the arterial pressure to nonpregnant levels, although when the increase in activity is excessive, hypertension may ensue.

Key Words: nervous system, autonomic • hypertension • blood pressure • pregnancy

This article has been cited by other articles:

				J. S. Gilbert, M. J. Ryan, B. B. LaMarca, M. Sedeek, S. R. Murphy, and J. P. Granger Pathophysiology of hypertension during preeclampsia: linking placental ischemia with endothelial dysfunction Am J Physiol Heart Circ Physiol, February 1, 2008; 294(2): H541 - H550. [Abstract] [Full Text] [PDF]

				L. Kvochina, E. M. Hasser, and C. M. Heesch Pregnancy increases baroreflex-independent GABAergic inhibition of the RVLM in rats Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2007; 293(6): R2295 - R2305. [Abstract] [Full Text] [PDF]

				S. Sen, G. Ozmert, H. Turan, E. Caliskan, A. Onbasili, and D. Kaya The Effects of Spinal Anesthesia on QT Interval in Preeclamptic Patients Anesth. Analg., November 1, 2006; 103(5): 1250 - 1255. [Abstract] [Full Text] [PDF]

				R. Korobochka, I. Gritsenko, R. Gonen, R. P. Ebstein, and G. Ohel Association between a functional dopamine D4 receptor promoter region polymorphism (-C521T) and pre-eclampsia: a family-based study Mol. Hum. Reprod., February 1, 2006; 12(2): 85 - 88. [Abstract] [Full Text] [PDF]

				H. Murai, S. Takata, M. Maruyama, M. Nakano, D. Kobayashi, K.-i. Otowa, M. Takamura, T. Yuasa, S. Sakagami, and S. Kaneko The activity of a single muscle sympathetic vasoconstrictor nerve unit is affected by physiological stress in humans Am J Physiol Heart Circ Physiol, February 1, 2006; 290(2): H853 - H860. [Abstract] [Full Text] [PDF]

				K. P. O'Hagan and J. A. Alberts Uterine artery blood flow and renal sympathetic nerve activity during exercise in rabbit pregnancy Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2003; 285(5): R1135 - R1144. [Abstract] [Full Text] [PDF]

				L. N. Graham, P. A. Smith, J. B. Stoker, A. F. Mackintosh, and D. A.S.G. Mary Time Course of Sympathetic Neural Hyperactivity After Uncomplicated Acute Myocardial Infarction Circulation, August 13, 2002; 106(7): 793 - 797. [Abstract] [Full Text] [PDF]