Placental barrier to atrial natriuretic peptide in rats

1989 ◽  
Vol 67 (1) ◽  
pp. 1-4 ◽  
Author(s):  
S. Mulay ◽  
D. R. Varma
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Maternal Plasma ◽  
Placental Barrier ◽  
Transplacental Passage ◽  
Pregnant Rats ◽  
Fetal Plasma ◽  
Maternal Urine ◽  
Maternal Metabolism ◽  
Atrial Natriuretic

Transplacental passage of 125I-labelled synthetic rat atrial natriuretic peptide (ANP) was investigated in 20-day pregnant rats under pentobarbitone anesthesia. Although significant quantities of radioactivity were detected in the fetal plasma after maternal injections and in the maternal plasma after fetal injections of 125I-labelled synthetic ANP, no fraction of the placentally transferred radioactivity was due to intact ANP. Despite a rapid maternal and fetal metabolism of ANP, both maternal and fetal plasma radioactivity remained relatively stable for at least 3 h and less than 10% of the injected radioactivity was excreted in the maternal urine during a 90-min period. It is concluded that ANP is not transported in either direction across the placenta in rats.Key words: atrial natriuretic peptide, placental barrier, urinary excretion, maternal metabolism, fetal metabolism.

Adenosine modulates hypoxia-induced atrial natriuretic peptide release in fetal sheep

1995 ◽  
Vol 269 (1) ◽  
pp. H282-H287 ◽  
Author(s):  
D. A. Ogunyemi ◽  
B. J. Koos ◽  
C. P. Arora ◽  
L. C. Castro ◽  
B. A. Mason
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Fetal Hemoglobin ◽  
Blood Gases ◽  
Fetal Sheep ◽  
Control Value ◽  
Fetal Plasma ◽  
Arterial Blood ◽  
The Right ◽  
Atrial Natriuretic

The effects of adenosine on atrial natriuretic peptide (ANP) secretion were determined in chronically catheterized fetal sheep (> 0.8 term). Adenosine was infused into the the right jugular vein for 1 h at 8 +/- 0.4 (5 fetuses), 160 +/- 8 (6 fetuses), and 344 +/- 18 micrograms.min-1.kg estimated fetal wt-1. Fetal arterial blood gases and pH were generally unaffected by adenosine, although mean arterial CO2 tension increased transiently by 2-5 Torr and pH fell progressively during the highest rate of infusion. During the intermediate and high infusion rates, fetal hemoglobin concentrations increased by 11-13% and mean fetal heart rate rose by 18% from a control value of approximately 167 beats/min. Mean arterial pressure was not affected during adenosine infusion. Adenosine significantly increased fetal plasma ANP levels, with maximum concentrations 1.80, 2.36, and 2.51 times greater than control means (142-166 pg/ml) for the respective infusion rates of 8, 160, and 344 micrograms.min-1.kg estimated fetal wt-1. In seven fetuses, reducing fetal arterial O2 tension by approximately 9-10 Torr from a control of 23 +/- 1.3 Torr increased plasma ANP concentrations approximately 2.4 times the control mean of 176 pg/min. Adenosine-receptor blockade with 8-(p-sulfophenyl)-theophylline reduced by 50% the maximum hypoxia-induced rise in plasma ANP concentrations. It is concluded that adenosine causes a dose-dependent rise in fetal plasma ANP concentrations and modulates fetal ANP release during hypoxia.

scholarly journals Effects of Environmental Temperature on Atrial Natriuretic Peptide (ANP) -granules of Auricular Cardiocytes and Plasma ANP Level in Pregnant Rats

1993 ◽  
Vol 42 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Hiroharu MIFUNE ◽  
Syusaku SUZUKI ◽  
Kiyoshi NOKIHARA ◽  
Yuta KOBAYASHI ◽  
Tomoyuki UEDA ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Environmental Temperature ◽  
Pregnant Rats ◽  
Atrial Natriuretic

Changes in concentration of human atrial natriuretic peptide in normal pregnancy and toxaemia

1987 ◽  
Vol 114 (2) ◽  
pp. 325-328 ◽  
Author(s):  
Y. Otsuki ◽  
E. Okamoto ◽  
I. Iwata ◽  
E. Nishino ◽  
N. Mitsuda ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Atrial Natriuretic Peptide ◽  
Pregnant Women ◽  
Natriuretic Peptide ◽  
Plasma Concentrations ◽  
Normal Pregnancy ◽  
Maternal Plasma ◽  
Human Atrial Natriuretic Peptide ◽  
Atrial Natriuretic

ABSTRACT Changes in concentration of human atrial natriuretic peptide (hANP) in normal and toxaemic pregnancy were examined. The maternal plasma concentration of hANP increased gradually during normal pregnancy to a maximum of 20·0±2·4 pmol/l (mean ± s.e.m.) after week 36 of pregnancy. From week 20, the plasma concentrations of hANP were significantly higher than those in non-pregnant women (9·3±2·0 pmol/l). In toxaemia with hypertension, maternal plasma hANP levels were increased after week 26 of pregnancy (37·7±6·0 pmol/l) compared with those in normal gravida at the same time (17·1±1·6 pmol/l). Maternal plasma hANP levels in toxaemia only with oedema were not different from those in normal gravida. J. Endocr. (1987) 114, 325–328

Vasorelaxation and vascular binding sites for atrial natriuretic peptide in pregnant rats

1988 ◽  
Vol 254 (6) ◽  
pp. H1027-H1033
Author(s):  
J. St-Louis ◽  
A. Parent ◽  
J. Gutkowska ◽  
J. Genest ◽  
E. L. Schiffrin
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Binding Sites ◽  
Female Rats ◽  
Pregnant Rats ◽  
Binding Characteristics ◽  
Vascular Bed ◽  
Mesenteric Vascular Bed ◽  
The Right ◽  
Atrial Natriuretic

To investigate the role of atrial natriuretic peptide (ANP) in pregnancy, we measured, in cyclic and pregnant female rats (9- and 21-days pregnant), the vascular responsiveness to ANP using helical strips of the thoracic aorta, the binding characteristics of 125I-labeled ANP in a membrane preparation of the mesenteric vascular bed, and the plasma level and the atrial content of immunoreactive ANP (IR-ANP). On aorta strips, concentration-response (C-R) curves to phenylephrine (PE) were measured and were slightly displaced to the right in the aorta of both groups of pregnant rats in comparison with the cyclic rats. There was a potentiation of the relaxant response of ANP on the PE-precontracted aortic strips of 9-day pregnant rats but it was not statistically modified in tissues of 21-day pregnant rats in comparison with strips from cyclic rats. The number of binding sites (Bmax) for ANP in the mesenteric vascular bed was similar in cyclic rats and the two groups of pregnant rats. The dissociation constant (KD) of ANP was lower in 9-day pregnant rats than in cyclic and 21-day pregnant ones. Plasma IR-ANP was not different in 9-day pregnant rats and cyclic rats but was markedly decreased at the end of gestation. Atrial content of IR-ANP increased at the end of gestation, but not in midpregnancy in comparison with cyclic rats. These 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.

Effect of a hypertonic saline load on plasma concentrations of atrial natriuretic peptide in fetal calves and their dams

1989 ◽  
Vol 121 (1) ◽  
pp. 5-9 ◽  
Author(s):  
M. Amadieu-Farmakis ◽  
J. Giry ◽  
J.-P. Barlet
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Hypertonic Saline ◽  
Natriuretic Peptide ◽  
Plasma Concentrations ◽  
Plasma Sodium ◽  
Third Trimester ◽  
Fetal Plasma ◽  
The Third ◽  
Sodium Load ◽  
Atrial Natriuretic

ABSTRACT Plasma concentrations of atrial natriuretic peptide (ANP) were studied in eight adult non-pregnant cows and in two groups of six chronically catheterized bovine fetuses and their mothers in the eighth month of pregnancy. The first group of fetuses was used for studying the effect of an acute i.v. sodium load (240 mmol NaCl/fetus) on fetal ANP; the second group acted as controls. The mean basal ANP levels in the third-trimester bovine fetus were three to four times higher than maternal values (39·5 ± 5·5 and 9·4 ± 0·6 pmol/l respectively; P<0·01). Basal maternal plasma ANP levels were twice as high in pregnant cows in the third trimester of pregnancy than in non-pregnant cows (9·4 ± 0·6 and 4·3 ± 0·7 pmol/l respectively; P<0·05). In response to an i.v. hypertonic saline injection, fetal plasma ANP levels increased significantly (P<0·01) to a maximum of 86·7± 17·6 pmol/l 10 min after the injection, and returned to baseline within 60 min after the treatment; during the 20 min following the i.v. sodium load, fetal plasma ANP correlated significantly with fetal plasma sodium concentrations (r 0·96; n=12) and with fetal plasma osmolality (r =0·94; n=12). No significant changes in maternal ANP values were observed in the two groups of animals. These results suggest that ANP secretion is stimulated during pregnancy in cows, and that, in the bovine fetus, a hypertonic sodium load appears to be a potent stimulus for ANP release. Journal of Endocrinology (1989) 121, 5–9

Receptors for Arg8-vasopressin, angiotensin II, and atrial natriuretic peptide in the mesenteric vasculature of pregnant rats

1991 ◽  
Vol 69 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Angèle Parent ◽  
Ernesto L. Schiffrin ◽  
Jean St-Louis
Keyword(s):  
Angiotensin Ii ◽  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Ang Ii ◽  
Receptor Density ◽  
Pregnant Rats ◽  
Receptor Kinetics ◽  
Vasoactive Peptides ◽  
Mesenteric Vascular Bed ◽  
Atrial Natriuretic

Blood pressure and sensitivity of blood vessels to vasoconstrictors are decreased in term-pregnant rats (20–21 days). To determine if changes in receptors for vasoactive peptides could account for these observations, receptor kinetics were measured for Arg8-vasopressin (AVP), angiotensin II (Ang II), and atrial natriuretic peptide (ANP) in the mesenteric vascular bed of the rat throughout pregnancy. Receptors for AVP were statistically similar in the five groups of animals (nonpregnant; pregnant 9, 15, and 21 days; and postpartum). The dissociation constant (KD) for [3H]AVP varied from 0.41 to 0.52 nmol/L (NS), while receptor density (Bmax) varied from 310 ± 110 to 455 ± 135 fmol/mg protein for six experimental measurements. Similar observations were made for Ang II receptors where KD of 125I-labelled Sar1, Ile8-Ang II was between 0.60 and 0.97 nmol/L and Bmax between 215 ± 30 and 250 ± 40 fmol/mg protein in the different groups. 125I-labelled ANP (101–126) receptors were markedly modified in terms of number of sites. Bmax was significantly increased during pregnancy (9 days, 429 ± 86; 15 days, 541 ± 54; 20 days, 438 ± 72) and decreased in the postpartum period (133 ± 21) by comparison with the nonpregnant group (245 ± 35 fmol/mg protein), while KD was similar in the different experimental groups (57 to 82 pmol/L). Despite these increases in receptor density, the vasorelaxant effects of ANP was only increased at 9 days of pregnancy. These results indicate that receptors for vasoconstrictor peptides (AVP and Ang II) are not altered during pregnancy and that receptor homospecific downregulation does not explain the decrease in sensitivity to vasoconstrictors at the end of pregnancy in the rat. Receptors for ANP are, however, markedly increased in number, but this did not result in an increase in the vascular action of the peptide throughout pregnancy.Key words: pregnancy, receptors, angiotensin, vasopressin, atrial natriuretic peptide.

Secretion of atrial natriuretic peptide and digoxin-like immunoreactive substance during pregnancy.

1988 ◽  
Vol 34 (5) ◽  
pp. 977-980 ◽  
Author(s):  
P Shrivastav ◽  
D S Gill ◽  
V D'Souza ◽  
P M O'Brien ◽  
P Dandona
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Umbilical Cord ◽  
Maternal Plasma ◽  
Cord Plasma ◽  
Significant Difference ◽  
Atrial Natriuretic

Abstract We investigated the secretion of atrial natriuretic peptide (ANP) and digoxin-like immunoreactive substance (DLIS) during pregnancy, labor, and the puerperium, as measured in maternal and umbilical cord plasma. There were no significant changes in maternal concentrations of ANP during all three periods, and the concentrations were similar to those found in nonpregnant controls and in umbilical cord plasma. Maternal concentrations of DLIS increased significantly in the second half of pregnancy, peaked during labor, then decreased abruptly within 24 h of expulsion of the infant and placenta to values approaching the nonpregnant range. DLIS concentrations in umbilical cord plasma, however, were significantly higher than in maternal plasma during labor. The abrupt fall in DLIS in maternal plasma and the absence of a significant difference in DLIS concentrations between arterial and venous cord plasma suggest that, during pregnancy, the fetus, not the placenta, is the source of DLIS in maternal plasma.

Pregnant rats are refractory to the natriuretic actions of atrial natriuretic peptide

1994 ◽  
Vol 267 (6) ◽  
pp. R1611-R1616 ◽  
Author(s):  
S. Masilamani ◽  
L. Castro ◽  
C. Baylis
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Volume Expansion ◽  
Renal Plasma Flow ◽  
Pregnant Rats ◽  
Arterial Blood ◽  
Renal Vascular ◽  
Renal Responses ◽  
Percent Decline ◽  
Atrial Natriuretic

Normal pregnant women and rats undergo a volume expansion. Atrial natriuretic peptide (ANP) is involved in volume homeostasis and is stimulated in response to volume expansion in nonpregnant animals, resulting in natriuresis and diuresis. The conscious, chronically catheterized rat was used to measure mean arterial blood pressure (MABP) and renal responses to administered ANP (160 ng.kg-1.min-1 i.v.) to determine if the actions of ANP are altered by pregnancy. These experiments examined virgin (n = 7) and pregnant rats, studied on gestational days 7-9 (n = 9) and 15-17 (n = 7). Renal clearance studies (with inulin and p-aminohippurate) were conducted in control conditions and during 60 min of ANP infusion. After the ANP infusion, plasma ANP concentrations were measured in virgin and pregnant rats. MABP fell with ANP infusion to similar absolute values in virgins (112 +/- 2 to 80 +/- 6 mmHg), 7- to 9-day pregnant (114 +/- 2 to 91 +/- 3 mmHg), and 15- to 17-day pregnant (107 +/- 2 to 88 +/- 4 mmHg) rats although the percent decline in MABP in 15- to 17-day pregnant rats was less than in virgins. Plasma ANP concentrations were similar in all groups. ANP had no effect on glomerular filtration rate, renal plasma flow, or renal vascular resistance in virgin or pregnant rats. ANP increased sodium excretion in virgins and in 7- to 9-day pregnant rats (+102 +/- 27 and +135 +/- 47%, respectively) but not in 15- to 17-day pregnant animals (+23 +/- 22%).(ABSTRACT TRUNCATED AT 250 WORDS)

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