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

1997 ◽  
Vol 155 (3) ◽  
pp. 523-530 ◽  
Author(s):  
P Vaillancourt ◽  
S Omer ◽  
R Palfree ◽  
DR Varma ◽  
S Mulay

The main objective of this study was to find out if the reported changes in the aldosterone-suppressant activity of atrial natriuretic peptide (ANP) during different hormonal states in rats are due to a modulation of ANP receptors. In zona glomerulosa cells, ribonuclease protection assay detected mRNAs for guanylate cyclase (GC)-coupled ANP GC-A and GC-B receptors, and for ANP C receptors, which are not coupled to GC. Western analysis using polyclonal anti-GC-A and anti-GC-B receptor antibodies revealed the presence of GC-A but not GC-B receptor proteins in zona glomerulosa cells. Pregnancy (days 7, 16 and 21), oestradiol-17 beta and progesterone decreased mRNAs for all the three ANP receptors in zona glomerulosa cells. Pregnancy decreased GC-A receptor proteins in zona glomerulosa cells, but these recovered to virgin values on day 2 postpartum. ANP receptor mRNAs in zona glomerulosa cells increased by postpartum day 2, but did not reach the values found in virgin rats. Zona fasciculata mainly contained GC-A receptor mRNA. It is concluded that ANP receptors in rat adrenal zona glomerulosa are modulated by pregnancy, oestrogen and progesterone; a decrease in ANP GC-A receptors during pregnancy might explain the accompanying decrease in the aldosterone-suppressant effects of ANP.

1999 ◽  
pp. 160-168 ◽  
Author(s):  
S Deloof ◽  
C De Seze ◽  
V Montel ◽  
A Chatelain

The effects of water deprivation for 3 days were studied in pregnant rats and their fetuses on day 21 of gestation. Maternal water deprivation induced a significant decrease of the body weight in both maternal and fetal rats. This weight loss was accompanied by significant increases in plasma osmolality and haematocrit in both maternal and fetal rats. Similarly, dehydration significantly decreased plasma atrial natriuretic peptide (ANP) concentrations and increased plasma aldosterone concentrations in maternal and fetal rats. Water-deprived maternal rats presented a significant increase in total ANP receptor density in isolated renal glomeruli and adrenal zona glomerulosa membranes. This increase was due to a significant increase in ANPc receptor density in both renal glomeruli and adrenal zona glomerulosa. The densities of total ANP, ANPb and ANPc receptors in fetal kidneys and adrenal glands were not affected by maternal dehydration. These results suggest that the dehydrated maternal rat is able to up-regulate the number of its ANP receptors in its kidneys and adrenal glands, in response to a decrease in plasma ANP concentrations. In contrast, the fetal rat does not seem to be able to regulate its own ANP receptors in response to maternal dehydration, in spite of a decrease in plasma ANP concentrations.


1974 ◽  
Vol 185 (1081) ◽  
pp. 375-407 ◽  

The densities of latex spheres and biological cells can be reliably determined from their sedimentation rate in an albumin gradient under unit gravitational force. The densities of zona glomerulosa and fasciculata cells of rat adrenals were found to be 1.072 ± 0.004 and 1.040 ± 0.001 respectively. Purified zona glomerulosa cells of rat adrenals can be prepared by gravitational sedimentation of dispersed cells from capsule strippings of the gland, which originally contain 3 to10% zona fasciculata contamination. Electron and phase microscopic examination of the sedimented glomerulosa cells and their steroidogenic response to ACTH and cyclic AMP indicate that they are reasonably free of contamination from zona fasciculata cells. Electron microscopic examination of the purified glomerulosa cells indicates that most of them are reasonably normal in structure. Their basal production of corticosterone is decreased after sedimentation. However, their maximal response of corticosterone output to serotonin and potassium and their response to all potassium concentrations is not significantly altered, indicating normal function for the cells producing steroids. Their maximal responses to ACTH, valine angiotensin II and cyclic AMP are decreased, but, at the doses used, steroidogenesis by the zona fasciculata contamination in the unfractionated preparation would be stimulated by these substances. Purified zona glomerulosa cells have about the same maximal response of corticosterone output (about twofold) to potassium, valine and isoleucine angiotensin II, serotonin and ACTH. The maximal response of the purified zona glomerulosa cells to cyclic AMP is similar to that elicited by valine and isoleucine angiotensin II, potassium, serotonin or ACTH. This indicates that if these stimuli act by increasing cyclic AMP output, then the maximal response of corticosterone output (about twofold) is defined by the limited response of the biosynthetic pathways to cyclic AMP.


1995 ◽  
Vol 269 (2) ◽  
pp. R245-R251 ◽  
Author(s):  
R. E. Blackburn ◽  
W. K. Samson ◽  
R. J. Fulton ◽  
E. M. Stricker ◽  
J. G. Verbalis

These studies evaluated the involvement of central oxytocin (OT) and atrial natriuretic peptide (ANP) receptors in the osmotic inhibition of hypovolemia-induced salt appetite. Rats were pretreated centrally with the A chain of the cytotoxin ricin conjugated to OT (rAOT) or ANP (rAANP) to selectively inactivate cells bearing these respective receptors, or rats were pretreated with the unconjugated A chain (rA) as a control. Hypovolemia was induced with subcutaneous colloid injections, and rats then were given either 2 M mannitol, which raises plasma osmolality but lowers plasma sodium, or 1 M NaCl, which raises both. Hypertonic mannitol inhibited saline ingestion in rA-treated control rats but stimulated ingestion in rAOT- and rAANP-treated rats, whereas hypertonic NaCl blunted saline ingestion in rA- and rAOT-treated rats but stimulated ingestion in rAANP-treated rats. Angiotensin II-induced saline intake was similarly potentiated in rAOT- and rAANP-treated rats, indicating that this treatment also activates central inhibitory OT and ANP pathways. These data suggest that central ANP receptors mediate both Na(+)- and osmolality-induced inhibition of NaCl ingestion, whereas central OT receptors primarily mediate osmolality-induced inhibition of NaCl ingestion in rats.


1990 ◽  
Vol 259 (1) ◽  
pp. F130-F137
Author(s):  
E. Nuglozeh ◽  
G. Gauquelin ◽  
R. Garcia ◽  
J. Tremblay ◽  
E. L. Schiffrin

The receptor for atrial natriuretic peptide (ANP) in the rat renal papilla was characterized pharmacologically. After solubilization and irreversible binding with disuccinimidylsuberate, it was shown on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) to be made of a single peptide of 125 kDa. The regulation of the renal papillary ANP receptor was studied in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. DOCA-salt rats had suppressed plasma renin activity and increased plasma ANP concentrations (408 +/- 35 vs. 133 +/- 12 pg/ml in uninephrectomized controls, P less than 0.01). The renal papilla was hypertrophied in DOCA-salt hypertensive rats (93 +/- 1 vs. 52 +/- 1 mg, P less than 0.01). The density of ANP sites in the papilla was significantly higher in DOCA-salt rats (141 +/- 31 fmol/papilla) than in controls (34 +/- 8 fmol/papilla, P less than 0.01). Affinity of sites in DOCA-salt rats and controls was similar. The production of guanosine 3',5'-cyclic monophosphate (cGMP) in renal papilla in response to ANP was significantly higher in DOCA-salt rats. In contrast to the renal papillary ANP receptor, acid-washed vascular and glomerular ANP sites were significantly decreased in density in DOCA-salt hypertensive rats. In blood vessels and glomeruli, both the high- and low-molecular mass receptor (as detected on SDS-PAGE under reducing conditions) was proportionately decreased in density in DOCA-salt hypertensive rats. The present results suggest that an increased number of ANP receptors and exaggerated cGMP response to ANP in the renal papilla may underlie the increased natriuretic responsiveness of the kidney to ANP in DOCA-salt hypertensive rats.


1989 ◽  
Vol 65 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Gérard Morel ◽  
Patrick Mesguich ◽  
Jean-Guy Chabot ◽  
Marthe Belles-Isles ◽  
Lydie Jeandel ◽  
...  

1993 ◽  
Vol 129 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Eduardo N Cozza ◽  
Mark F Foecking ◽  
Maria del Carmen Vila ◽  
Celso E Gomez-Sanchez

Atrial and brain natriuretic peptides specifically bind to primary cultures of calf adrenal glomerulosa cells. Binding of both natriuretic peptides to the same receptor has been proved by: a Dixon plot showing competitive effects for the binding of 125I-labeled brain natriuretic peptide in the presence of increasing concentrations of unlabeled atrial natriuretic peptide; a Scatchard plot showing a lower dissociation constant (Kd) for atrial natriuretic peptide than for brain natriuretic peptide binding, but the maximum binding (Bmax) values were the same; autoradiography of sodium dodecyl sulfate polyacrylamide gels after cross-linking of 125I-labeled atrial natriuretic peptide and 125I-labeled brain natriuretic peptide, showing the same molecular weights for both peptide receptors—a single 66-kD band in whole cells and a main band at 125 kD in membranes. C-Type atrial natriuretic peptide only slightly displaced atrial natriuretic peptide binding. Angiotensin II- and potassium-mediated stimulation of aldosterone production were inhibited strongly and to the same degree by atrial and brain natriuretic peptide but only slightly by C-type atrial natriuretic peptide. Stimulation of aldosterone production mediated by adrenocorticotropin was only partially inhibited by atrial and brain natriuretic peptide, while baseline aldosterone was not affected. These results suggest that atrial and brain natriuretic peptide bind to the same receptors and provoke the same effects on aldosterone production. The weak effects found with C-type atrial natriuretic peptide suggest that the primary culture of calf adrenal glomerulosa cells contain the guanylate cyclase A receptor.


1989 ◽  
Vol 30 (4) ◽  
pp. 613-613
Author(s):  
Masaki Kurihara ◽  
Kimihiro Yamashita ◽  
Masami Niwa ◽  
Kazuto Shigematu ◽  
Masayori Ozaki ◽  
...  

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