nitroglycerin has a relaxing effect on the smooth muscles of organs including uterus. this study investigates the effect of intravenous nitroglycerin in emergency cesarean sections in which rapid and transient uterine relaxation for rapid and nontraumatic extraction of the fetus is necessary. sixty pregnant women who were been candidates for emergency cesarean and needed rapid uterine relaxatio...

PURPOSE To investigate whether, in the second trimester of pregnancy, placental T2 relaxation time (determined using magnetic resonance imaging (MRI)) is related to impedance to flow in the uterine arteries. METHODS In 40 singleton pregnancies at 24-29 weeks' gestation, uterine artery pulsatility index (PI) was measured by Doppler ultrasound and T2 relaxation time was measured by echo planar ...

Objective The aim of this study was to investigate the effect and mechanism by which progesterone regulates uterine contraction in late pregnant rats. Results Progesterone caused concentration-dependent relaxation of uterine strips that was enhanced compared with control nontreated uterine strips. Uterine strips incubated with progesterone showed a significant increase in TREK-1 mRNA expressi...

It has been previously shown that vasoactive intestinal polypeptide (VIP) induces endothelium-dependent relaxation of the human uterine artery. However, the nature of the mediator of the VIP-induced endothelium-dependent relaxation of the human uterine artery has not yet been determined. Therefore these experiments were undertaken to examine the effects of VIP on human uterine arteries and to e...

Recently, strong evidence has suggested that nitric oxide (NO) synthesis is significantly increased in the uterine artery during pregnancy, which may mediate the increased blood flow to the uterus that is characteristic of pregnancy. We therefore investigated the nature of the mediators of acetylcholine (ACh)-induced relaxation in pregnant guinea-pig uterine arterial rings. ACh (0.1 nM to 60 mi...

BACKGROUND The ex utero intrapartum treatment (EXIT) procedure is a technique designed to establish an airway at the time of delivery in fetuses at risk of airway obstruction and requires maintenance of uterine relaxation to continue placental perfusion and prevent placental separation. We describe the use of intravenous nitroglycerin to maintain uterine relaxation during the EXIT procedure. ...

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 us...

We tested the hypothesis that chronic high-altitude (3,820 m) hypoxia during pregnancy was associated with the upregulation of endothelial nitric oxide (NO) synthase (eNOS) protein and mRNA in ovine uterine artery endothelium and enhanced endothelium-dependent relaxation. In pregnant sheep, norepinephrine-induced dose-dependent contractions were increased by removal of the endothelium in both c...

Ion channels are interesting molecules since they mediate not only uterine contraction but also uterine relaxation. We have examined the expression, function, and correlation between the large conductance calcium-activated potassium (BKCa) channel, beta2 adrenoceptor (AR), and long-lasting (L) type calcium (Ca2+) channel. These are the main channels and receptor that are involved in the uterine...

The uterine vasculature plays an important role during pregnancy by providing adequate perfusion of the maternal-fetal interface. To this end, substantial remodeling of the uterine vasculature occurs with consequent changes in responsiveness to contractile agents. The purpose of our study was to characterize the vasorelaxant effects of estrogens on vascular smooth muscles of the rat uterine art...