Inhibition of the tocolytic activity of atrial natriuretic factor by progesterone and potentiation by progesterone receptor antagonist RU486 in rats

@article{Potvin1991InhibitionOT,
  title={Inhibition of the tocolytic activity of atrial natriuretic factor by progesterone and potentiation by progesterone receptor antagonist RU486 in rats},
  author={William J. Potvin and Shree Mulay and Daya R. Varma},
  journal={British Journal of Pharmacology},
  year={1991},
  volume={104}
}
1 The influence of progesterone on the activity of atrial natriuretic factor (ANF) on rat myometrial motor activity was determined in vitro. 2 ANF inhibited the tension development by myometrium from cycling or oestrogen‐treated rats in a dose‐dependent manner; maximal inhibition was 100%. 3 Injections of progesterone into rats inhibited the tocolytic activity of ANF in a dose‐ and time‐dependent manner. The tocolytic effects of ANF were completely abolished by 3 daily injections of 1 mg kg… 

Contractility of late pregnant rat myometrium is refractory to activation of soluble but not particulate guanylate cyclase.

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Spontaneous uterine contractions are under the control of both soluble and particulate guanylate cyclases; the former is dependent on gestational age but the latter is not, while the inhibitory effects of the nitric oxide donors diethylamine Nitric oxide, 3-morpholino-sydnominine, and authentic nitrics were attenuated in uterine tissues from animals in late stages of pregnancy.

Downregulation of adrenal atrial natriuretic peptide receptor mRNAs and proteins by pregnancy in rats.

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Regulation of cGMP-induced relaxation and cGMP-dependent protein kinase in rat myometrium during pregnancy.

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It is concluded that myometrial tissues from pregnant rats are not sensitive to relaxation by cGMP and this insensitivity to cG MP is accompanied by progesterone-mediated decreases in the level of PKG expression.

Inhibitory effects of electrical stimulation on delivery in pregnant rats.

Evidence that spontaneous contractile activity in the rat myometrium is not inhibited by NO‐mediated increases in tissue levels of cyclic GMP

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The results of the present study indicate that cyclic GMP does not play an important role in the control of contractility in the rat uterus.

Regulation of cGMP-induced relaxation and cGMP-dependent protein kinase in rat myometrium during pregnancy.

TLDR
It is concluded that myometrial tissues from pregnant rats are not sensitive to relaxation by cGMP and this insensitivity to cG MP is accompanied by progesterone-mediated decreases in the level of PKG expression.

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Refractoriness of the gravid rat uterus to tocolytic and biochemical effects of atrial natriuretic peptide

TLDR
Exposure of the myometrium to circulating and placentally‐produced progesterone is responsible for the pregnancy‐induced decrease in the effects of ANP on myometrial particulate guanylate cyclase activity and cyclic GMP concentrations and in turn onMyometrial tension development.

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TLDR
The hormonal state did not change dissociation constants for ANF binding to myometrial preparations and a single high-affinity binding site for 125I-labelled ANF(1-28) was detected in myometrian membrane preparations partially purified by discontinuous sucrose gradient centrifugation.

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TLDR
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TLDR
It is suggested that oestradiol is the major regulator of myometrial activity during the cycle and that progesterone interferes with the action of ostradiol, thereby paradoxically increasing uterine activity.

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TLDR
The results indicate that despite the reported important increase in blood volume during gestation the secretion of ANP is not increased and suggest that the ANP-volume relationship is reset during pregnancy in the rat.

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TLDR
The alterations in IUGR are consistent with sustained activation of the fetal renin-angiotensin system and suggest altered vascular responsiveness to ANP, which may have a role in the regulation of fetoplacental blood flow.

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TLDR
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TLDR
The low concentration of ANF in fetal urine suggests that ANF is probably metabolized and/or reabsorbed by the fetal kidney, and it is demonstrated that immunoreactive AnF is present in the fetal circulation at levels higher than those found in the mother.