Vascular catecholamine sensitivity during pregnancy in the ewe

McLaughlin, Margaret K.; Keve, Tara M.; Cooke, R. T.

doi:10.1016/0002-9378(89)90085-9

Cited by 22 publications

(2 citation statements)

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“…The finding of increased NO release in uterine artery rings by pregnancy is consistent with our previous results obtained in the perfused uterine artery preparation (39). The increase in basal NO release in pregnant uterine arteries is likely to play an important role in refractoriness to ␣-adrenoceptor agonists occurring during pregnancy in uterine arteries (1,19,24,35). In the present study, endothelium removal significantly increased norepinephrine-induced contractions of pregnant uterine arteries and shifted its dose-response curve to the left, suggesting an important role of endothelium-mediated substances in the regulation of contractile sensitivity of norepinephrine in pregnant uterine arteries.…”

Section: Discussionsupporting

confidence: 90%

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺

Xiao

Pearce

Zhang

2001

American Journal of Physiology-Heart and Circulatory Physiology

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The present study tested the hypothesis that the pregnancy-associated increase in endothelium-dependent relaxation of the uterine artery was mediated primarily by an increase in nitric oxide (NO) release, resulting in a reduction in smooth muscle intracellular Ca(2+) concentration ([Ca(2+)](i)). Uterine arteries obtained from nonpregnant and near-term (140 days gestation) pregnant sheep were used. The Ca(2+) ionophore A23187 induced endothelium-dependent relaxations in both nonpregnant and pregnant uterine arteries, with an increased relaxation in the pregnant tissue. In contrast, endothelium-independent relaxations induced by sodium nitroprusside were the same in nonpregnant and pregnant arteries. In addition, removal of the endothelium significantly increased noradrenaline-induced contractions in pregnant, but not nonpregnant, uterine arteries. In accordance, pregnancy increased both basal and A23187-stimulated NO releases in the uterine artery. Simultaneous measurement of tension and [Ca(2+)](i) in the smooth muscle demonstrated a linear correlation with the slope of unity between A23187-induced relaxation and the reduction of [Ca(2+)](i) in both nonpregnant and pregnant uterine arteries. The A23187-induced reduction of [Ca(2+)](i) was significantly enhanced in pregnant, compared with nonpregnant, uterine arteries. The results indicate that pregnancy increases NO release, which, through decreasing [Ca(2+)](i) in the smooth muscle, accounts for the increased endothelium-dependent relaxation of the uterine artery. Signal transduction pathways distal to NO production are not changed by pregnancy.

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Section: Discussionsupporting

confidence: 90%

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺

Xiao

Pearce

Zhang

2001

American Journal of Physiology-Heart and Circulatory Physiology

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“…It is well known that pregnancy alters reactivity of uterine noradrenaline actions on this vascular bed (Barton et al, vasculature to a variety of vasoconstrictor substances 1974; Van Nimwegen & Dyer, 1974;Anderson et al, 1977; (Griendling et al, 1985;McLaughlin et al, 1989;Weiner et Assali et al, 1981;Nunotani et al, 1985;Magness & al., 1989;Steele et al, 1993). This vascular alteration Rosenfeld, 1986;Weiner et al, 1989;Steele et al, probably mediates the increased blood flow to the uterus that 1993).…”

Section: Introductionmentioning

confidence: 99%

Effect of the vascular endothelium on noradrenaline‐induced contractions in non‐pregnant and pregnant guinea‐pig uterine arteries

Jovanović¹,

Grbović²,

Jovanović

1995

British J Pharmacology

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1 The effect of pregnancy on noradrenaline-mediated contraction of guinea-pig uterine artery rings with both intact and denuded endothelium was investigated.2 Noradrenaline (25 nM -I00 #Lm) induced concentration-dependent contraction of non-pregnant and pregnant guinea-pig uterine arterial rings with intact endothelium with similar pD2 and maximal response values (non-pregnant: pD2= 5.85 ± 0.02, maximal response = 121 ± 8.2%; pregnant: pD2 = 5.81 ± 0.04, maximal response = 122 + 9.1%). Removal of endothelium did not affect noradrenaline-induced contractions in non-pregnant guinea-pig uterine artery (pD2= 5.97 ± 0.02, maximal response = 119 ± 8.6%). In contrast, in arteries from pregnant guinea-pigs, removal of endothelium shifted concentration-response curve for noradrenaline to the left, without affecting maximal response value (pD2 = 6.36 ± 0.03, maximal response = 120 ± 9.0%).3 The pKA values for noradrenaline were: 5.76 ± 0.09 and 5.82 ±0.10 for non-pregnant guinea-pig uterine artery with intact and denuded endothelium, respectively and 5.74 ± 0.09 and 5.72 ± 0.07 for pregnant guinea-pig uterine artery with intact and denuded endothelium, respectively. 4 The receptor occupancy-response relationship for noradrenaline was linear for all types of vessels, except for pregnant guinea-pig uterine artery with denuded endothelium, since half-maximal response to noradrenaline was obtained with 44.8 ± 6.9% (non-pregnant guinea-pig uterine artery with intact endothelium), 43.3 ± 6.1% (non-pregnant guinea-pig uterine artery with denuded endothelium) and 44.3 ± 6.3% (pregnant guinea-pig uterine artery with intact endothelium) receptor occupancy. In pregnant guinea-pig uterine artery with denuded endothelium, occupancy-response relationship for noradrenaline was non-linear since half-maximal response to noradrenaline was obtained with 19.7 ± 3.3% receptor occupancy.5 N0-monomethyl-L-arginine(100gM) and indomethacin (10 gM) did not affect concentration-response curve for noradrenaline in guinea-pig uterine arteries, regardless of pregnancy status or endothelial condition.6 In quiescent preparations, the z-adrenoceptor antagonists, prazosin (5-50nM) and yohimbine (1-10gM) produced parallel rightward shifts of the curves for noradrenaline and the slopes of the Schild plots were not significantly different from unity. The plots constrained to a slope of unity gave the following -log KB values: prazosin vs. yohimbine 8.78 ± 0.03 vs. 6.41 ± 0.02 for non-pregnant guineapig uterine artery with intact endothelium, 8.95 ± 0.03 vs. 6.34 ± 0.02 for non-pregnant guinea-pig uterine artery with denuded endothelium, 8.91 ± 0.01 vs. 6.44 ± 0.03 for pregnant guinea-pig uterine artery with intact endothelium and 9.07 ± 0.01 vs. 6.52 ± 0.03 for pregnant guinea-pig uterine artery with denuded endothelium.7 It is concluded that initially there is no difference in noradrenaline action between uterine arteries from non-pregnant and pregnant guinea-pigs, but after removal of the endothelium the pregnant guinea-pig uterine artery is more sensitive...

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Maternal Cardiovascular and Other Physiologic Responses to the Endocrinology of Pregnancy

Magness¹

1998

Endocrinology of Pregnancy

119

184

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Vascular catecholamine sensitivity during pregnancy in the ewe

Cited by 22 publications

References 10 publications

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺

Effect of the vascular endothelium on noradrenaline‐induced contractions in non‐pregnant and pregnant guinea‐pig uterine arteries

Maternal Cardiovascular and Other Physiologic Responses to the Endocrinology of Pregnancy

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Vascular catecholamine sensitivity during pregnancy in the ewe

Cited by 22 publications

References 10 publications

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca2+

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca2+

Effect of the vascular endothelium on noradrenaline‐induced contractions in non‐pregnant and pregnant guinea‐pig uterine arteries

Maternal Cardiovascular and Other Physiologic Responses to the Endocrinology of Pregnancy

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Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺

Pregnancy enhances endothelium-dependent relaxation of ovine uterine artery: role of NO and intracellular Ca²⁺