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

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.

1987 ◽  
Vol 116 (2) ◽  
pp. 235-240 ◽  
Author(s):  
Kozo Ota ◽  
Tokihisa Kimura ◽  
Meiichi Ito ◽  
Minoru Inoue ◽  
Masaru Shoji ◽  
...  

Abstract. In order to study the effect of atrial tachycardia on the release of atrial natriuretic peptide (ANP), AVP, and methionine enkephalin (M-Enk), plasma concentrations of these peptides in the right ventricle were determined in patients with various arrhythmias (N = 10) during cardiac catheterization and incremental atrial pacing. Each pacing (100 per min, the maximum rate for 1:1 atrioventricular conduction, and 200 per min) lasted 4 to 5 min. Plasma ANP was significantly increased from 53.1 ± 12.2 in the resting condition to 168.9 ± 59.9 pmol/l at a pacing rate of 200 beats per min (P < 0.05); plasma AVP tended to decrease, but not significantly, and plasma M-Enk did not change at all. Pulse pressure in the right atrium (PPRA) and mean right atrial pressure (MRAP) tended to increase during the pacing, and at the rate of 200 beats per min PPRA was significantly higher than at the rate of 100 beats per min. Mean arterial blood pressure, plasma osmolality, and plasma sodium and potassium concentrations did not change significantly. There were significant correlations between plasma ANP and PPRA, MRAP and heart rate. These results indicate that atrial pacing stimulates ANP release with a rise in right atrial pressure, but does not influence M-Enk and AVP releases.


1986 ◽  
Vol 64 (7) ◽  
pp. 1017-1022 ◽  
Author(s):  
J. R. Ledsome ◽  
N. Wilson ◽  
A. J. Rankin ◽  
C. A. Courneya

In 12 chloralose anaesthetized dogs plasma concentration of immunoreactive atrial natriuretic peptide (IR-ANP) was measured using a radioimmunoassay. Plasma IR-ANP was 74 ± 4.8 pg/mL (mean ± SE) and increased by 39 ± 4.1 pg/mL when left atrial pressure was increased by 10 cm H2O during partial mitral obstruction. Observation of the time course of the changes in IR-ANP during atrial distension showed that IR-ANP was increased within 2 min of atrial distension and declined after atrial distension, with a half-time of 4.5 min. The time course of the changes in IR-ANP was unaffected by vagotomy or administration of atenolol. Maximum electrical stimulation of the right ansa subclavia failed to produce any change in IR-ANP. IR-ANP was higher in coronary sinus plasma than in femoral arterial plasma confirming that the heart was the source of the IR-ANP. The results support the hypothesis that IR-ANP is released from the heart by a direct effect of stretch of the atrial wall rather than by a neural or humoral mechanism involving a reflex from atrial receptors.


1989 ◽  
Vol 26 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Barbara Y Hargrave ◽  
Harriet S Iwamoto ◽  
Abraham M Rudolph

Physiology ◽  
2000 ◽  
Vol 15 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Luis Gabriel Melo ◽  
Stephen C. Pang ◽  
Uwe Ackermann

Recent findings in atrial natriuretic peptide (ANP) transgenic and gene knockout mouse models uncovered a tonic vasodilatory effect of this hormone that contributes to chronic blood pressure homeostasis. With elevated salt intake, ANP-mediated antagonism of the renin-angiotensin system is essential for blood pressure constancy, suggesting that a deficiency in ANP activity may underlie the etiology of sodium-retaining disorders.


Endocrinology ◽  
2009 ◽  
Vol 150 (5) ◽  
pp. 2382-2387 ◽  
Author(s):  
Karim Sabrane ◽  
Markus-N. Kruse ◽  
Alexandra Gazinski ◽  
Michaela Kuhn

Atrial natriuretic peptide (ANP), via its guanylyl cyclase (GC)-A receptor, plays a key role in the regulation of arterial blood pressure (ABP) and volume. Endothelial-restricted deletion of GC-A in mice [endothelial cell (EC) GC-A knockout (KO)] resulted in hypervolemic hypertension, demonstrating that the endothelium participates in the hypotensive and hypovolemic actions of ANP. Published studies showed that ANP modulates the release of the vasoactive factors nitric oxide (NO) and endothelin-1 (ET-1) from cultured endothelia. Based on these observations, we examined the role of these endothelial factors in ANP-dependent vasodilatation (studied in isolated arteries) and chronic regulation of ABP (measured in awake mice by tail-cuff plethysmography). ANP induced concentration-dependent vasorelaxations of aortic, carotid, and pulmonary arteries. These responses were not different between control and EC GC-A KO mice, and were significantly enhanced after inhibition of NO synthase [by N(G)-nitro-l-arginine-methyl ester]. Intravenous administration of N(G)-nitro-l-arginine-methyl ester to conscious mice significantly increased ABP. The extent of these hypertensive reactions was similar in EC GC-A KO mice and control littermates (increases in systolic blood pressure by ∼25 mm Hg). Conversely, antagonism of ET-1/endothelin-A receptors with BQ-123 reduced ABP significantly and comparably in both genotypes (by ∼11 mm Hg). Finally, the vascular and tissue expression levels of components of the NO system and of immunoreactive ET-1 were not different in control and EC GC-A KO mice. We conclude that the endothelium, but not modulation of endothelial NO or ET-1, participates in the chronic regulation of ABP by ANP.


1998 ◽  
Vol 274 (3) ◽  
pp. R711-R717 ◽  
Author(s):  
Robin Donna Deliva ◽  
Uwe Ackermann

Atrial natriuretic peptide (ANP) inhibits renal sympathetic nerve activity (RSNA), provided the vagi are intact. Afferents from chemosensitive cardiopulmonary receptors are specifically required. Such receptors produce the Bezold-Jarisch reflex, are prominent on the ventricular epicardium, and are richly supplied with 5-hydroxytryptamine type 3 (5-HT3) receptors. We tested the hypothesis that epicardial 5-HT3-sensitive neurons mediate depressor effects of ANP. Through a special catheter, anesthetized, sinoaortically denervated rats received pericardial test injections of ANP (28-amino acid rat ANP; 100 and 1,000 ng) in the presence or absence of 5-HT3 antagonist (Ondansetron, 20 μg/kg; n = 9). In other groups we observed the effects of systemic ANP while blocking either epicardial or systemic 5-HT3 receptors. Arterial blood pressure (ABP), heart rate, and RSNA were recorded continuously. Intravenous ANP (100 or 200 ng) decreased ABP and RSNA significantly. In contrast, intrapericardial ANP (100 or 1,000 ng) caused no significant fall in ABP or RSNA. Both intravenous and pericardial Ondansetron reduced the effects of intravenous ANP significantly, but the intravenous antagonism was significantly greater. We conclude that epicardial chemosensitive afferents are not sensitive to ANP and that sympathoinhibitory effects of ANP arise from a 5-HT3 agonist that cannot be produced when ANP is confined to the pericardial space.


1993 ◽  
Vol 75 (6) ◽  
pp. 2353-2359 ◽  
Author(s):  
M. A. Haxhiu ◽  
E. C. Deal ◽  
E. Van Lunteren ◽  
N. S. Cherniack

The effects of somatostatin and atrial natriuretic peptide applied topically to the ventral surface of the medulla (VMS) on tracheal tone and phrenic nerve activity (Phr) were studied in chloralose-anesthetized and paralyzed cats artificially ventilated with 7% CO2 in O2. Surface application of drugs to the chemosensitive areas of the VMS significantly decreased tracheal tension measured by changes in pressure in a balloon placed in a bypassed segment of the trachea (Ptseg). Application of somatostatin (9 cats) caused a mean decrease in Ptseg from 17.3 +/- 1.8 (SE) to 4.3 +/- 1.4 cmH2O (P < 0.01) and a reduction in Phr from 24.9 +/- 3.4 to 10.3 +/- 3.4 units (P < 0.05). Like somatostatin, application of atrial natriuretic peptide to the VMS (5 cats) produced tracheal relaxation (Ptseg decreased from 19.3 +/- 2.6 to 9.9 +/- 1.3 cmH2O, P < 0.01), but in contrast there was an insignificant reduction in Phr (from 18.5 +/- 3.6 to 16.1 +/- 3.8 units, P > 0.05). When parasympathetic activity was abolished by atropine methylnitrate and tracheal tone was restored with 5-hydroxytryptamine, somatostatin and atrial natriuretic peptide applied on the VMS had no effect on tracheal pressure, suggesting that observed changes were not caused by direct action of peptides on tracheal smooth muscle via the bloodstream or by facilitation of inhibitory pathways. Both somatostatin and atrial natriuretic peptide applications were associated with a slight but significant decrease in arterial blood pressure. These data suggest that somatostatin and atrial natriuretic peptide acting on the chemosensitive structure of the VMS may play significant roles in modulating para-sympathetic outflow to airway smooth muscle.


1988 ◽  
Vol 255 (3) ◽  
pp. R449-R455 ◽  
Author(s):  
H. Soejima ◽  
R. J. Grekin ◽  
J. P. Briggs ◽  
J. Schnermann

Studies were performed in rats to determine the minimum infusion rate of atrial natriuretic peptide (ANP) associated with detectable changes in renal function and to determine the change in plasma levels of the peptide produced by these infusion rates. Synthetic ANP-(4-28) was administered to anesthetized euvolemic rats at rates ranging between 10 and 230 ng.kg-1.min-1 for 30 min. Significant natriuresis and diuresis were seen with an infusion of 20 ng.kg-1.min-1. At this rate of infusion, plasma ANP averaged 279 +/- 19.9 pmol/l (vs. 158 +/- 11.8 pmol/l in control rats). A transient increase in K excretion was seen with infusions higher than 100 ng.kg-1.min-1. There was no measurable change in glomerular filtration rate up to an infusion of 160 ng.kg-1.min-1. A significant decrease in mean arterial pressure was only seen with an infusion of 230 ng.kg-1.min-1. In volume-expanded rats, infusion of ANP at 10 ng.kg-1.min-1 induced a significant natriuresis. Our results indicate that natriuresis and diuresis are caused by an infusion of ANP which produces changes in plasma ANP concentration that may well result from stimulation of endogenous ANP release. In contrast, changes in K excretion, glomerular filtration rate, and arterial blood pressure may require changes in plasma ANP that are not easily achievable by physiological interventions.


2011 ◽  
Vol 300 (3) ◽  
pp. R624-R629 ◽  
Author(s):  
Toshiyoshi Matsukawa ◽  
Takenori Miyamoto

We investigated the effect of the intravenous infusion of atrial natriuretic peptide (ANP) on the response of plasma arginine vasopressin (AVP) levels to intravenous infusion of angiotensin II (ANG II) in healthy individuals. Intravenous infusion of ANP (10 ng·kg−1·min−1) slightly but significantly decreased plasma AVP levels, while intravenous infusion of ANG II (10 ng·kg−1·min−1) resulted in slightly increased plasma AVP levels. ANG II infused significant elevations in arterial blood pressure and central venous pressure (CVP). Because the elevation in blood pressure could have potentially inhibited AVP secretion via baroreceptor reflexes, the effect of ANG II on blood pressure was attenuated by the simultaneous infusion of nitroprusside. ANG II alone produced a remarkable increase in plasma AVP levels when infused with nitroprusside, whereas the simultaneous ANP intravenous infusion (10 ng·kg−1·min−1) abolished the increase in plasma AVP levels induced by ANG II when blood pressure elevation was attenuated by nitroprusside. Thus, ANG II increased AVP secretion and ANP inhibited not only basal AVP secretion but also ANG II-stimulated AVP secretion in humans. These findings support the hypothesis that circulating ANP modulates AVP secretion, in part, by antagonizing the action of circulating ANG II.


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