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Resumo Fundamento A ação do peptídeo natriurético atrial (ANP) na natriurese, diurese e vasodilatação, resistência à insulina, fígado, rim e tecido adiposo pode contribuir para o desenvolvimento metabólico e cardiovascular saudável. Embora o nível circulante de ANP seja reduzido em pacientes com obesidade, sua resposta à perda de peso ainda é pouco explorada em populações pediátricas. Objetivo Avaliar os efeitos das variações do ANP em resposta à intervenção interdisciplinar para perda de peso na Síndrome Metabólica (SMet) e nos riscos cardiometabólicos em adolescentes com obesidade. Métodos 73 adolescentes com obesidade participaram de uma terapia interdisciplinar para perda de peso de 20 semanas, incluindo uma abordagem clínica, nutricional, psicológica e de exercícios físicos. A composição corporal, análises bioquímicas e pressão sanguínea foram avaliadas. A SMet foi classificada de acordo com a Federação Internacional de Diabetes (IDF) (2007). Após o tratamento, os voluntários foram divididos de acordo com os níveis de plasma do ANP aumento (n=31) ou ANP redução (n=19). Resultados Ambos os grupos apresentaram redução significativa de peso corporal, índice de massa corporal (IMC) e circunferências de cintura, pescoço e quadril (CC, CP e CQ, respectivamente), e aumento da massa livre de gordura (MLG). É interessante observar que houve uma redução significativa na gordura corporal, na razão de TG/HDL-c e na prevalência de SMet (de 23% para 6%) somente no grupo com ANP aumento. Conclusão Este estudo sugere que o aumento nos níveis séricos de ANP após a terapia para perda de peso pode estar associado a melhorias nos riscos cardiometabólicos e na prevalência reduzida de SMet em adolescentes com obesidade.

Abstract Background The action of atrial natriuretic peptide (ANP) on natriuresis, diuresis and vasodilatation, insulin resistance, liver, kidney, and adipose tissue may contribute to the healthy metabolic and cardiovascular development. Even though the circulating level of ANP is reduced in patients with obesity, its response to weight loss remains poorly explored in pediatric populations. Objective To evaluate the effects of ANP variations in response to interdisciplinary weight loss intervention on metabolic syndrome (MetS) and cardiometabolic risks in adolescents with obesity. Methods 73 adolescents with obesity attended a 20-week clinical interdisciplinary weight loss therapy including clinical, nutritional, psychological and exercise training approach. Body composition, biochemical analyses and blood pressure were evaluated. MetS was classified according to the International Diabetes Federation (IDF) (2007). After the treatment, volunteers were divided according to Increasing (n=31) or Decreasing (n=19) ANP plasma levels. Results Both groups present significant reduction of body weight, Body Mass Index (BMI), waist, neck and hip circumferences (WC, NC and HC, respectively) and increasing fat-free mass (FFM). Interestingly, a significant reduction in body fat, TG/HDL-c ratio and MetS prevalence (from 23% to 6%) was observed in the Increased ANP group only. Conclusion This study suggests that an increase in ANP serum levels after weight loss therapy could be associated with improvements in cardiometabolic risks and the reduced prevalence of MetS in adolescents with obesity.

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Abstract Ischemic postconditioning (IPTC) brings cardioprotection endogenously, Atrial natriuretic peptide (ANP) produces the same effect. It happens due to down expression of endothelial nitric oxide synthase (eNOS). Thus, experimental protocol associating IPTC has been formulated to find the role of ANP in the cardioprotection of heart in OVX rats. For this experiment, heart was isolated from OVX rat and held tightly on Langendorff's apparatus in a manner that ischemia of 30 min and reperfusion of 120 min were also given. Simultaneously, IPTC with four cycles of 5 min ischemia and 5 min reperfusion of each was applied. Parameters like size of myocardial infarct, levels of lactate dehydrogenase (LDH) and release of creatine kinase- MB (CK-MB) in coronary effluent were noted after each stage of experiment for ensuring the extent of myocardial injury. Some significant changes were also seen in the histopathology of cardiovascular tissues. The cardio-protection has been made by four cycles of IPTC. It was confirmed by decline in the size of myocardial infarct. It diminishes the release of LDH and CK-MB in heart of OVX rat. Thus, IPTC induces cardio-protection in the isolated heart from OVX rat. Perfusion of ANP associating with IPTC favors the cardioprotection which is further confirmed by rise in the NO release and heart rate. The level of myocardial damage changes using IPTC, IPTC+OVX, IPTC+OVX+ANP, IPTC+ OVX+ANP+L-NAME and other groups were observed significantly and were found to be less than those in I/R control group. Thus, it is recommended that ANP involving IPTC restores attenuated cardio-protection in OVX rat heart. Therefore, Post-conditioning is useful in various clinical aspects.

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Atrial natriuretic peptide belongs to the family of natriuretic peptides, a system with natriuretic, diuretic, and vasodilator effects that opposes to renin-angiotensin system. In addition to its classic actions, atrial natriuretic peptide exerts a nephroprotective effect given its antioxidant and anti-inflammatory properties, turning it as a beneficial agent against acute and chronic kidney diseases. This minireview describes the most relevant aspects of atrial natriuretic peptide in the kidney, including its renal synthesis, physiological actions through specific receptors, the importance of its metabolism, and its potential use in different pathological scenarios.

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Nitric oxide (NO) negatively modulates the secretion of vasopressin (AVP), oxytocin (OT) and atrial natriuretic peptide (ANP) induced by the increase in extracellular osmolality, whereas carbon monoxide (CO) and hydrogen sulphide (H2 S) act to potentiate it; however, little information is available for the osmotic challenge model about whether and how such gaseous systems modulate each other. Therefore, using an acute ex vivo model of hypothalamic and neurohypophyseal explants (obtained from male 6/7-week-old Wistar rats) under conditions of extracellular iso- and hypertonicity, we determined the effects of NO (600 µmol L-1 sodium nitroprusside), CO (100 µmol L-1 tricarbonylchloro[glycinato]ruthenium [II]) and H2 S (10 mmol L-1 sodium sulphide) donors and nitric oxide synthase (NOS) (300 µmol L-1 Nω -methyl-l-arginine [LNMMA]), haeme oxygenase (HO) (200 µmol L-1 Zn(II) deuteroporphyrin IX 2,4-bis-ethylene glycol [ZnDPBG]) and cystathionine ß-synthase (CBS) (100 µmol L-1 aminooxyacetate [AOA]) inhibitors on the release of hypothalamic ANP and hypothalamic and neurohypophyseal AVP and OT, as well as on the activities of NOS, HO and CBS. LNMMA reversed hyperosmolality-induced NOS activity, and enhanced hormonal release by the hypothalamus and neurohypophysis, in addition to increasing CBS and hypothalamic HO activity. AOA decreased hypothalamic and neurohypophyseal CBS activity and hormonal release, whereas ZnDPBG inhibited HO activity and hypothalamic hormone release; however, in both cases, AOA did not modulate NOS and HO activity and ZnDPBG did not affect NOS and CBS activity. Thus, our data indicate that, although endogenous CO and H2 S positively modulate AVP, OT and ANP release, only NO plays a concomitant role of modulator of hormonal release and CBS activity in the hypothalamus and neurohypophysis and that of HO activity in the hypothalamus during an acute osmotic stimulus, which suggests that NO is a key gaseous controller of the neuroendocrine system.

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ABSTRACT: Background: The aim of this study was to determine the presence of alterations in the natriuretic systems of atrial natriuretic peptide and renal dopamine in a model of metabolic syndrome induced by fructose overload and to associate them with changes in systolic blood pressure, renal function, Na+/K+-ATPase status and microalbuminuria. Methods: Male Sprague-Dawley rats were divided into control (C) and fructose (F) groups receiving drinking water or a fructose so-lution (10% W/V), respectively, for 4, 8 and 12 weeks. L-dopa and dopamine, sodium, creatinine and albumin were measured in urine and ANP, insulin, sodium and creatinine in plasma. Systolic blood pressure was measured by indirect method and the renal activity and expression of Na+/K+-ATPase as well as the renal expression of A- and C-type natriuretic peptide receptors were assessed. results: Fructose overload was associated with a significant increase in insulinemia and systolic blood pressure levels and a decrease in urinary sodium excretion since week 4. A significant increase in L-dopa excretion and a decrease in dopamine excretion (increased urinary L-dopa/dopamine ratio) due to fructose overload were observed since week 4 with a decrease in plasma atrial natriuretic peptide at weeks 8 and 12. These changes were accompanied by increased activity and expression of Na+/ K+-ATPase, decreased A-type natriuretic peptide receptor and increased C-type natriuretic peptide receptor expression. Microalbuminuria was observed at week 12 of fructose overload.

RESUMEN: Objetivos: El objetivo del trabajo consistió en determinar la existencia de alteraciones en los sistemas natriuréticos del péptido natriurético atrial y dopamina renal en un modelo de síndrome metabólico por sobrecarga de fructosa y asociarlas con cambios en la presión arterial sistólica, función renal, estado de la Na+, K+-ATPasa y microalbuminuria. Material y Métodos: Ratas macho Sprague-Dawley fueron divididas en grupos control (C) y fructosa (F) con agua o solución de F (10%P/V) para beber durante 4, 8 y 12 semanas. En orina, se midió L-dopa y dopamina, sodio, creatinina y albúmina; y en plasma péptido natriurético atrial, insulina, sodio y creatinina. La presión arterial sistólica fue medida por método indirecto. Se midió la actividad y expresión de la Na+, K+-ATPasa así como la expresión del receptor de péptidos natriuréticos A y C renales. resultados: La sobrecarga de fructosa se asoció con el aumento de la insulinemia y la presión arterial sistólica, y con la disminución en la excreción urinaria de sodio desde la semana 4. La excreción urinaria de L-dopa se incrementó y la de dopamina disminuyó (cociente L-dopa/dopamina incrementado) por sobrecarga de fructosa desde la semana 4 y el péptido natriurético atrial plasmático se redujo en las semanas 8 y 12. Estos cambios fueron acompañados por un incremento de la actividad y expresión de la Na+, K+-ATPasa, disminución del receptor de péptidos natriuréticos A y aumento del C. La microalbuminuria se observó en la semana 12 de sobrecarga de fructosa. Conclusiones: Las alteraciones del péptido natriurético atrial y de la dopamina renal se asociaron con el desarrollo de hipertensión arterial y precedieron a la aparición de microalbuminuria, por lo que se pudo establecer una asociación temporal entre la alteración de ambos sistemas y el desarrollo de daño renal.

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Cardiac biomarkers for clinical and experimental heart diseases have previously been evaluated in rabbits. However, several laboratory assays performed and reported with inconsistent results. This study aimed to assess the effects of breed on serum ANP, CRP, and ACE and establish reference interval (RI) for these biomarkers in a large population of healthy rabbits. Ninety-seven adult rabbits from five breeds were included in this study. Assays were performed using specific ELISA commercial kits. The results were statistically analyzed using ANOVA, Tukey test (p<0.05), arithmetic mean, RI of mean, and standard deviation. A significant effect of breed was shown, indicating different RI between breeds for each biomarker. In conclusion, this study demonstrated that breed is an important physiological variable influencing the normal values of cardiac markers in healthy rabbits.(AU)

Biomarcadores cardíacos têm sido avaliados em coelhos para avaliação clínica e experimental das doenças cardíacas. Entretanto diferentes testes laboratoriais têm sido utilizados e relatados, sem uma confluência de resultados. Os objetivos deste estudo foram verificar os efeitos de diferentes raças de coelhos sobre as concentrações séricas de ANP, CRP e ACE, além de estabelecer intervalor de referência para estes biomarcadores em uma população de coelhos saudáveis. Foram utilizados noventa e sete coelhos de cinco diferentes raças. Os exames foram realizados pela metodologia de ELISA, por meio de kits comerciais específicos. Os resultados foram analisados estatisticamente os testes de ANOVA e Tukey (p<0,05), média aritmética, intervalo de referência da média e desvio padrão. Um efeito significativo da raça foi observado sobre as variáveis estudadas, indicando diferentes intervalos de referência entre as raças para cada biomarcador. Em conclusão, este estudo demonstrou que a raça é uma variável fisiológica importante que influencia os valores normais destes biomarcadores em coelhos saudáveis.(AU)

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Cardiac biomarkers for clinical and experimental heart diseases have previously been evaluated in rabbits. However, several laboratory assays performed and reported with inconsistent results. This study aimed to assess the effects of breed on serum ANP, CRP, and ACE and establish reference interval (RI) for these biomarkers in a large population of healthy rabbits. Ninety-seven adult rabbits from five breeds were included in this study. Assays were performed using specific ELISA commercial kits. The results were statistically analyzed using ANOVA, Tukey test (p<0.05), arithmetic mean, RI of mean, and standard deviation. A significant effect of breed was shown, indicating different RI between breeds for each biomarker. In conclusion, this study demonstrated that breed is an important physiological variable influencing the normal values of cardiac markers in healthy rabbits.(AU)

Biomarcadores cardíacos têm sido avaliados em coelhos para avaliação clínica e experimental das doenças cardíacas. Entretanto diferentes testes laboratoriais têm sido utilizados e relatados, sem uma confluência de resultados. Os objetivos deste estudo foram verificar os efeitos de diferentes raças de coelhos sobre as concentrações séricas de ANP, CRP e ACE, além de estabelecer intervalor de referência para estes biomarcadores em uma população de coelhos saudáveis. Foram utilizados noventa e sete coelhos de cinco diferentes raças. Os exames foram realizados pela metodologia de ELISA, por meio de kits comerciais específicos. Os resultados foram analisados estatisticamente os testes de ANOVA e Tukey (p<0,05), média aritmética, intervalo de referência da média e desvio padrão. Um efeito significativo da raça foi observado sobre as variáveis estudadas, indicando diferentes intervalos de referência entre as raças para cada biomarcador. Em conclusão, este estudo demonstrou que a raça é uma variável fisiológica importante que influencia os valores normais destes biomarcadores em coelhos saudáveis.(AU)

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OBJECTIVE: To assess the effects of oral low-dose and non-oral hormone therapy (HT) on ultra-sensitive C-reactive protein (CRP), atrial natriuretic peptide (ANP), and cardiovascular risk factors in postmenopause. METHODS: In this randomized, cross-over study, 44 recently postmenopausal women, with no clinical evidence of cardiovascular disease, received oral low-dose HT (estradiol 1 mg + drospirenone 2 mg/day) for 3 months. Forty-two patients received non-oral, conventional HT (1.5 mg/day percutaneous 17ß-estradiol gel or equivalent for nasal route) for 3 months followed by 200 mg/day micronized progesterone by the vaginal route (14 days during each menstrual period). After 3 months, patients were crossed over without washout. Post-HT vs. pre-HT measures were determined: lipids, glucose, body mass index, waist circumference, fibrinogen, CRP-stratified levels, and ANP levels. The study was registered at clinical trials.gov (NCT01432028). RESULTS: The mean age was 51 ± 3 years and the mean time since the menopause was 22 ± 10 months. CRP-stratified high levels decreased in a higher number of non-oral HT patients, who moved to intermediate and low levels (p = 0.02). No effect of HT was observed on ANP levels (baseline 67.4 (18.4-104.5), low-dose oral 43.5 (14.4-95.9), non-oral 39.8 (15.5-67.5) pg/ml). Markers of endothelial function did not worsen with either low-dose oral or non-oral HT: von Willebrand factor (baseline 118 ± 37%, low-dose oral 119 ± 38%, non-oral 108 ± 3%, p < 0.01), fibrinogen (baseline 356 ± 58 mg/dl; low-dose oral 343 ± 77 mg/dl; non-oral 326 ± 71 mg/dl, p < 0.01). CONCLUSIONS: Low-dose oral and non-oral HT for 6 months had neutral or beneficial effects in recently postmenopausal women with no clinical evidence of cardiovascular disease.

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Atrial natriuretic peptide (ANP) is known to regulate ovarian functions, such as follicular growth and steroid hormone production. The aim of the present study was to investigate the natriuretic peptide system in a rat model of chronic anovulation, the rat polycystic ovary. Adult female Wistar rats received a single subcutaneous injection of 2mg estradiol valerate to induce polycystic ovaries, while the control group received vehicle injection. Two months later, their ovaries were quickly removed and analyzed. Polycystic ovaries exhibited marked elevation of testosterone and estradiol levels compared to control ovaries. The levels of ANP and the expression of ANP mRNA were highly reduced in the polycystic ovaries compared to controls. By immunohistochemistry, polycystic ovaries showed weaker ANP staining in stroma, theca cells and oocytes compared to controls. Polycystic ovaries also had increased activity of neutral endopeptidase, the main proteolytic enzyme that degrades natriuretic peptides. ANP receptor C mRNA was reduced and ANP binding to this receptor was absent in polycystic ovaries. Collectively, these results indicate a downregulation of the natriuretic peptide system in rat polycystic ovary, an established experimental model of anovulation with high ovarian testosterone and estradiol levels. Together with previous evidence demonstrating that ANP inhibits ovarian steroidogenesis, these findings suggest that low ovarian ANP levels may contribute to the abnormal steroid hormone balance in polycystic ovaries.

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OBJECTIVES: Acute ST-elevation myocardial infarction is associated with ventricular dysfunction due to ischemia-induced progressive myocardial damage. The decrease in ventricular compliance causes left atrial dilatation and stretching of the atrial myocardium, which are the main stimuli for the secretion of atrial natriuretic peptide. The aim of this study was to evaluate left atrial dimensions and atrial natriuretic peptide levels in patients early after their first acute ST-elevation myocardial infarction and assess the probable interaction between coronary lesions and these measurements. METHODS: A total of 110 patients with acute myocardial infarction and 50 controls were studied. Plasma atrial natriuretic peptide was measured at admission. Left ventricular function, diameter, and volume index were evaluated using transthoracic echocardiography. Gensini and vessel scores of the patients who underwent coronary angiography were calculated. RESULTS: Plasma atrial natriuretic peptide in the patients with myocardial infarction was increased compared with that in controls (3.90±3.75 vs. 1.35±0.72 nmol/L, p<0.001). Although the left atrial diameter was comparable in patients and controls, the left atrial volume index was increased in patients with acute myocardial infarction (26.5±7.1 vs. 21.3±4.9 mL/m2, p<0.01). Multivariate regression analysis showed a strong independent correlation between the left atrial volume index and the plasma atrial natriuretic peptide level (β = 0.23, p = 0.03). CONCLUSIONS: The left atrial volume index and plasma atrial natriuretic peptide level were correlated in patients with acute myocardial infarction. .

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