| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1-adrenergic stimulation
1 Women's Health Research
Center and 2 Division of
Cardiology,
Decreased
contractile response to vasoconstrictors in uterine and nonuterine
vessels contributes to increased blood flow to the uterine circulation
during normal pregnancy. Pregnancies complicated by preeclampsia
and/or chronic hypoxia show a reversal or diminution of these
pregnancy-associated changes. We sought to determine whether chronic
hypoxia opposes the reduction in contractile response in uterine and
nonuterine vessels during normal pregnancy and, if so, whether
decreased basal nitric oxide (NO) activity was involved. We examined
the contractile response to phenylephrine (PE) in guinea pig uterine
artery (UA), mesenteric artery (MA), and thoracic aorta (TA) rings
isolated from nonpregnant or pregnant guinea pigs that had been exposed
throughout gestation to either low (1,600 m,
n = 47) or high (3,962 m,
n = 43) altitude. In the UA, pregnancy
reduced contractile sensitivity to PE and did so similarly at low and
high altitude (EC50: 4.0 × 10
8 nonpregnant, 9.3 × 108 pregnant at low
altitude; 4.8 × 108
nonpregnant, 1.0 ×108
pregnant at high altitude; both P < 0.05). Addition of the NO synthase inhibitor
nitro-L-arginine (NLA; 200 mM)
to the vessel bath increased contractile sensitivity in the pregnant UA
(P < 0.05) and eliminated the effect
of pregnancy at both altitutes. NLA also raised contractile sensitivity
in the nonpregnant high-altitude UA, but contractile response without
NLA did not differ in the high- and low-altitude animals. In the MA,
pregnancy decreased contractile sensitivity to PE at high altitude
only, and this shift was reversed by NO inhibition. In the TA, neither
pregnancy nor altitude affected contractile response, but NO inhibition raised contractile response in nonpregnant and pregnant TA at both
altitudes. We concluded that pregnancy diminished contractile response
to PE in the UA, likely as a result of increased NO activity, and that
these changes were similar at low and high altitude. Counter to our
hypothesis, chronic hypoxia did not diminish the pregnancy-associated
reduction in contractile sensitivity to PE or inhibit basal NO activity
in the UA; rather it enhanced, not diminished, basal NO activity in the
nonpregnant UA and the pregnant MA.
nitric oxide; vasoreactivity; guinea pig; preeclampsia
This article has been cited by other articles:
|
|
 |
|
  S. N. Mateev, R. Mouser, D. A. Young, R. P. Mecham, and L. G. Moore Chronic hypoxia augments uterine artery distensibility and alters the circumferential wall stress-strain relationship during pregnancy J Appl Physiol, June 1, 2006; 100(6): 1842 - 1850. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Erkinaro, T. Kavasmaa, M. Pakkila, G. Acharya, K. Makikallio, S. Alahuhta, and J. Rasanen Ephedrine and phenylephrine for the treatment of maternal hypotension in a chronic sheep model of increased placental vascular resistance Br. J. Anaesth., February 1, 2006; 96(2): 231 - 237. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Xiao and L. Zhang Calcium Homeostasis and Contraction of the Uterine Artery: Effect of Pregnancy and Chronic Hypoxia Biol Reprod, April 1, 2004; 70(4): 1171 - 1177. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Xiao, X. Huang, S. Bae, C. A. Ducsay, L. D. Longo, and L. Zhang Cortisol-mediated regulation of uterine artery contractility: effect of chronic hypoxia Am J Physiol Heart Circ Physiol, February 1, 2004; 286(2): H716 - H722. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Mateev, A. H. Sillau, R. Mouser, R. E. McCullough, M. M. White, D. A. Young, and L. G. Moore Chronic hypoxia opposes pregnancy-induced increase in uterine artery vasodilator response to flow Am J Physiol Heart Circ Physiol, March 1, 2003; 284(3): H820 - H829. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. M. Bird, L. Zhang, and R. R. Magness Possible mechanisms underlying pregnancy-induced changes in uterine artery endothelial function Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2003; 284(2): R245 - R258. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Xiao, I. M. Bird, R. R. Magness, L. D. Longo, and L. Zhang Upregulation of eNOS in pregnant ovine uterine arteries by chronic hypoxia Am J Physiol Heart Circ Physiol, February 1, 2001; 280(2): H812 - H820. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.J.D. Lucca, A.S.O. Adeagbo, and N.L. Alsip Oestrous cycle and pregnancy alter the reactivity of the rat uterine vasculature Hum. Reprod., December 1, 2000; 15(12): 2496 - 2503. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. M. White, R. E. McCullough, R. Dyckes, A. D. Robertson, and L. G. Moore Chronic hypoxia, pregnancy, and endothelium-mediated relaxation in guinea pig uterine and thoracic arteries Am J Physiol Heart Circ Physiol, June 1, 2000; 278(6): H2069 - H2075. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
