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… 
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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
Despite an increased intravascular volume of 70% during gestation, cardiac content of ANF and the renal and vascular responsiveness to this peptide are similar to those in virgin rats, suggesting resetting of ANf-volume relationships during pregnancy.
Vasorelaxation and vascular binding sites for atrial natriuretic peptide in pregnant rats.
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 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.
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TLDR
Changes in concentration of human atrial natriuretic peptide (hANP) in normal and toxaemic pregnancy were examined and maternal plasma hANP levels in toxaemia only with oedema were not different from those in normal gravida.
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TLDR
The results indicate that although plasma ANP concentration rose to high levels during acute NaCl loading in pregnant goats, this effect was not important for the natriuresis, and instead, thenatriuretic response to ANP appears attenuated during pregnancy, and also during lactation.
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