Atrial natriuretic peptide in pregnant and lactating goats

Olsson, Kerstin; Karlberg, B. E.; Eriksson, Leif

doi:10.1530/acta.0.1200519

Cited by 24 publications

(17 citation statements)

References 18 publications

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“…This plasma volume expansion of pregnancy also occurs in animal models and is the result of net, continual renal sodium and fluid retention (1). Previous findings in our laboratory and others have indicated that in normal pregnancy the natriuretic response to atrial natriuretic peptide (ANP) is blunted, therefore promoting sodium retention and plasma volume expansion (7,12,15,16).ANP signals through the second messenger cGMP, and we have reported that PDE-5 activity and protein abundance in the inner medullary collecting duct are selectively increased in normal pregnancy (14). In addition, selective, intrarenal PDE-5 inhibition with sildenafil reverses the blunted response to infused ANP seen in normal pregnancy (10).…”

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confidence: 76%

The natriuretic and diuretic response to dopamine is maintained during rat pregnancy

Sasser

Baylis²

2008

American Journal of Physiology-Renal Physiology

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Sasser JM, Baylis C. The natriuretic and diuretic response to dopamine is maintained during rat pregnancy. Am J Physiol Renal Physiol 294: F1342-F1344, 2008. First published April 9, 2008 doi:10.1152/ajprenal.00067.2008.-During pregnancy, there is a marked plasma volume expansion due to renal sodium retention. Pregnant rats exhibit a blunted response to natriuretic stimuli that signal via cGMP, and expression and activity of the cGMP phosphodiesterase PDE-5 are upregulated in the inner medullary collecting duct during pregnancy. Here, we tested the hypothesis that the natriuretic response to a cAMP agonist, dopamine, is maintained during pregnancy. Anesthetized pregnant (day 16) and age-matched virgin Sprague-Dawley rats were used to determine whether dopamine-cAMP-mediated natriuresis remains intact in pregnant rats. Blood pressure, renal clearances of inulin and p-aminohippuric acid, and excretion of sodium were measured during baseline and dopamine infusion periods. Pregnant rats had a lower blood pressure and hematocrit at baseline than their age-matched virgin counterparts. Dopamine infusion decreased blood pressure and increased glomerular filtration rate and renal plasma flow in virgin but not pregnant rats. Dopamine infusion also increased urine volume, sodium excretion, and the fractional excretion of sodium to a similar extent in virgin and pregnant rats. These results indicate that a cAMP-mediated natriuresis and diuresis (stimulated by dopamine) persists in pregnant rats. pregnancy; plasma volume; sodium retention; cAMP NORMAL PREGNANT WOMEN UNDERGO a progressive plasma volume expansion which begins in the first trimester, peaks near gestational week 32, and remains elevated until term (9, 18). The demands of fetal development require this increased circulating volume, and failure to expand plasma volume is correlated with complications of pregnancy and intrauterine growth retardation (5, 11). This plasma volume expansion of pregnancy also occurs in animal models and is the result of net, continual renal sodium and fluid retention (1). Previous findings in our laboratory and others have indicated that in normal pregnancy the natriuretic response to atrial natriuretic peptide (ANP) is blunted, therefore promoting sodium retention and plasma volume expansion (7,12,15,16).ANP signals through the second messenger cGMP, and we have reported that PDE-5 activity and protein abundance in the inner medullary collecting duct are selectively increased in normal pregnancy (14). In addition, selective, intrarenal PDE-5 inhibition with sildenafil reverses the blunted response to infused ANP seen in normal pregnancy (10). Increased renal PDE-5 will degrade cGMP and inhibit the normal natriuretic response, contributing to the volume expansion in normal pregnancy. However, it is currently unknown whether the blunted natriuresis of pregnancy is specific to cGMP-dependent pathways.Therefore, the purpose of this study was to test the hypothesis that a cAMP-mediated natriuresis remains intact in pregnant rats. To test ...

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confidence: 76%

The natriuretic and diuretic response to dopamine is maintained during rat pregnancy

Sasser

Baylis²

2008

American Journal of Physiology-Renal Physiology

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“…However, other evidence suggests that a refractoriness develops to ANP that would allow the antinatriuretic RAAS to predominate. For example, the natriuretic response to infused ANP is blunted in pregnant goats (24). We have previously reported that the conscious, chronically catheterized pregnant rat becomes refractory to the tubular natriuretic (but not hemodynamic) actions of ANP (18).…”

Section: Discussionmentioning

confidence: 99%

Increased renal phosphodiesterase-5 activity mediates the blunted natriuretic response to ANP in the pregnant rat

Knight¹,

Snellen²,

Humphreys³

et al. 2007

American Journal of Physiology-Renal Physiology

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Knight S, Snellen H, Humphreys M, Baylis C. Increased renal phosphodiesterase-5 activity mediates the blunted natriuretic response to ANP in the pregnant rat. Am J Physiol Renal Physiol 292: F655-F659, 2007. First published September 26, 2006; doi:10.1152/ajprenal.00309.2006.-Normal rat pregnancy is characterized by plasma volume expansion due to renal sodium retention and is associated with a blunted response to natriuretic stimuli, such as atrial natriuretic peptide (ANP). ANP signals via cGMP, and phosphodiesterases (PDE) inactivate cGMP and terminate the natriuretic response. We previously reported that increased medullary PDE-5 activity occurs in rat pregnancy, which may be the mechanism of the blunted natriuretic effect of ANP. Here, we used anesthetized 16-day pregnant and virgin rats to investigate whether intrarenal infusion of a selective PDE-5 inhibitor, sildenafil, would reverse the blunted response to ANP in pregnancy. We measured blood pressure, renal clearances using inulin and p-aminohippuric acid, and electrolyte excretion at baseline and during an ANP infusion. ANP caused a fall in mean arterial pressure in all groups, and sildenafil induced a further reduction. We observed an increase in sodium excretion with ANP in all rats, but this was blunted in the vehicle-infused pregnant rats. This could not be explained by differences in renal hemodynamics and was of tubular origin, as reflected by the reduced rise in fractional excretion of sodium with ANP in the pregnant rat given vehicle (45 Ϯ 11 vs. 204 Ϯ 49%; P Ͻ 0.05). However, intrarenal sildenafil increased the natriuretic response and the rise in fractional excretion of sodium to the virgin value (226 Ϯ 23 vs. 245 Ϯ 73%; not significant), whereas the blunting persisted in the contralateral kidney. This demonstrates that increased intrarenal PDE-5 mediates the blunted natriuretic response to ANP during pregnancy and may contribute to the physiological volume expansion. plasma volume; sodium retention; cGMP; hormone signaling; hormone resistance DURING NORMAL PREGNANCY, a marked and progressive plasma volume expansion occurs in ϳ50% of women and in 70 -100% of rats (1, 9). The failure of plasma volume to expand during pregnancy is associated with poor outcome and is often a characteristic of preeclampsia (4). The gestational plasma volume expansion is clearly the result of a net sodium retention (1, 9).The physiological regulation of sodium balance and plasma volume is maintained by a number of counterbalancing systems, including the natriuretic nitric oxide (NO), atrial natriuretic peptide (ANP), pressure-natriuresis system, and the antinatriuretic renin-angiotensin-aldosterone (RAAS) and sympathetic nervous systems. In pregnancy, continual plasma volume expansion and sodium retention suggest that the balance is shifted toward sodium-retaining systems, and yet both NO and ANP levels are maintained or elevated. However, we previously reported that the renal natriuretic actions of ANP are blunted during pregnancy in the rat, as is the pressure na...

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“…Circulating ANP levels during normal pregnancy in the rat [18,27], goat [32], and human [33] have been reported by several authors. During pregnancy, the plasma ANP level has been suggested to undergo a gradual increase due to increased blood volume and cardiac output [33].…”

Section: Discussionmentioning

confidence: 84%

“…Further, alteration in atrial stretch, such as those induced by acute blood volume expansion, stimulates the secretion of ANP from the mammalian cardiac atria [19,20,35]. Therefore, several investigators have suggested that the release of ANP was accelerated by blood volume expansion and distension of the cardiac atria during pregnancy [9,25,32,33,40], and have postulated a rise in plasma ANP levels during pregnancy that would parallel the known changes in blood volume. However, the present findings were not consistent with this postulation.…”

Section: Discussionmentioning

confidence: 99%

“…In normal pregnancy, the blood volume increases in parallel with the increasing body weight during gestation [1,3,14]. This could be expected to stimulate the release of ANP, and this view is explained by an increase in plasma ANP level during normal pregnancy in human [9,33], goat [32] and cow [40]. However, no change has been reported in pregnant rat [27], or in human [37].…”

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confidence: 99%

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Synthesis and Secretion of A-Type Natriuretic Peptide in the Auricular Cardiocytes during Pregnancy and Lactation in Mouse.

Mifune

Suzuki

Honda

et al. 2000

The Journal of Veterinary Medical Science

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. A-type (atrial) natriuretic peptide (ANP) levels in the auricular cardiocytes and plasma were examined by immunohistochemistry, electron microscopy, and radioimmunoassay in pregnant and lactating mice. Additionally, the cardiocyte ANP mRNA expression was measured by the polymerase chain reaction method. ANP-immunoreactivity (IR) and the number of ANP-granules in the cardiocytes on the 18th day of gestation were greater than those in virgin controls, but the plasma ANP concentration decreased on the 18th day of gestation. On the day of delivery, ANP-IR and the number of ANP-granules in the cardiocytes were decreased compared to those during the pregnancy and to those in virgin controls, and then began to increase continually until the 15th day of lactation. Plasma ANP concentration after delivery was significantly higher than that during pregnancy, and than that in virgin controls, and continued to increase until the 15th day of lactation. Cardiocyte ANP mRNA expression was highest on the day of delivery compared to that in all the other times. In conclusion, these results suggested that the circulating systems of ANP during pregnancy and lactation were regulated differentially. nonpregnant, nonlactating controls. Moreover, we have examined the ANP mRNA levels in atrial cardiocytes to determine any change in the synthesis system of ANP during these periods. MATERIALS AND METHODS Animals:The heart and blood were obtained from 10 pregnant mice of the ICR strain (Jcl: ICR, CLEA Japan, Inc., Osaka, Japan) in each group on the 10th and 18th day of gestation, and from 10 lactating mice (same strain) in each group on the day of delivery, and on the 5th, 15th and 21st day after delivery. The day of insemination was defined as 0-day of gestation, and the day of delivery was regarded as 0-day of lactating. Normal vergin mice were used as control. All animals were kept in automatically controlled rooms (temperature: 24 ± 1°C; humidity: 55 ± 5%; automatic lighting: 6:00 a.m. to 8:00 p.m.) and fed with a pellet diet CE-2 (CLEA Japan, Inc., Osaka, Japan) and water ad libitum. These animals were sacrificed under sodium pentobarbital anesthesia (50 mg/kg, i. p.) and their hearts and blood were removed. All experiments were undertaken in accordance with Guide for Animal Experimentation, Kurume University.Immunohistochemistry: The left auricular tissue blocks were fixed in Zamboni's solution for 24 hr at 4°C. After washing with 0.15 M phosphate-buffered saline (PBS) at pH 7.3, they were dehydrated, embedded in paraffin and sectioned at 5 µm. Prior to immunohistochemical staining, the deparaffinized sections were incubated in absolute A-type (atrial) natriuretic peptide (ANP) is a circulating hormone with a wide range of biological effects, including natriuresis, diuresis and vasodilation, and it may play an important role in the regulation of blood pressure and body fluid homeostasis [5,12,29]. This peptide hormone is mainly produced and stored within secretory granules in the atrial cardiocytes [5,11,[21][22][23]. Dist...

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Atrial natriuretic peptide in pregnant and lactating goats

Cited by 24 publications

References 18 publications

The natriuretic and diuretic response to dopamine is maintained during rat pregnancy

The natriuretic and diuretic response to dopamine is maintained during rat pregnancy

Increased renal phosphodiesterase-5 activity mediates the blunted natriuretic response to ANP in the pregnant rat

Synthesis and Secretion of A-Type Natriuretic Peptide in the Auricular Cardiocytes during Pregnancy and Lactation in Mouse.

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