RESUMEN

BACKGROUND/AIMS: To investigate the role of the sympathetic nervous system (SNS) and renin-angiotensin system (RAS) in renal ischemia/reperfusion-induced (I/R) cardiac inflammatoryprofile. METHODS: Left kidney ischemia was induced in male C57BL/6 mice for 60 min, followed by reperfusion for 12 days, and treatment with or without atenolol, losartan, or enalapril. The expression of vimentin in kidney and atrial natriuretic factor (ANF) in the heart has been investigated by RT-PCR. In cardiac tissue, levels of ß1-adrenoreceptors, adenylyl cyclase, cyclic AMP-dependent protein kinase (PKA), noradrenaline, adrenaline (components of SNS), type 1 angiotensin II receptors (AT1R), angiotensinogen/Ang II and renin (components of RAS) have been measured by Western blotting and HPLC analysis. A panel of cytokines - tumour necrosis factor (TNF-α), interleukin IL-6, and interferon gamma (IFN-γ) - was selected as cardiac inflammatory markers. RESULTS: Renal vimentin mRNA levels increased by >10 times in I/R mice, indicative of kidney injury. ANF, a marker of cardiac lesion, increased after renal I/R, the values being restored to the level of Sham group after atenolol or enalapril treatment. The cardiac inflammatory profile was confirmed by the marked increase in the levels of mRNAs of TNF-α, IL-6, and IFN-γ. Atenolol and losartan reversed the upregulation of TNF-α expression, whereas enalapril restored IL-6 levels to Sham levels; both atenolol and enalapril normalized IFN-γ levels. I/R mice showed upregulation of ß1-adrenoreceptors, adenylyl cyclase, PKA and noradrenaline. Renal I/R increased cardiac levels of AT1R, which decreased after losartan or enalapril treatment. Renin expression also increased, with the upregulation returning to Sham levels after treatment with SNS and RAS blockers. Angiotensinogen/Ang II levels in heart were unaffected by renal I/R, but they were significantly decreased after treatment with losartan and enalapril, whereas increase in renin levels decreased. CONCLUSION: Renal I/R-induced cardiac inflammatory events provoked by the simultaneous upregulation of SNS and RAS in the heart, possibly underpin the mechanism involved in the development of cardiorenal syndrome.

Asunto(s)

Riñón/metabolismo , Miocardio/metabolismo , Sistema Renina-Angiotensina , Sistema Nervioso Simpático/metabolismo , Animales , Atenolol/farmacología , Atenolol/uso terapéutico , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Catecolaminas/metabolismo , Enalapril/farmacología , Enalapril/uso terapéutico , Interleucina-6/metabolismo , Losartán/farmacología , Losartán/uso terapéutico , Masculino , Ratones , Ratones Endogámicos C57BL , Receptor de Angiotensina Tipo 1/genética , Receptor de Angiotensina Tipo 1/metabolismo , Receptores Adrenérgicos beta 1/genética , Receptores Adrenérgicos beta 1/metabolismo , Sistema Renina-Angiotensina/efectos de los fármacos , Daño por Reperfusión/tratamiento farmacológico , Daño por Reperfusión/metabolismo , Daño por Reperfusión/patología , Sistema Nervioso Simpático/efectos de los fármacos , Factor de Necrosis Tumoral alfa/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Vimentina/genética , Vimentina/metabolismo

RESUMEN

Neonatal lambs, as with human and other neonates, have low arrhythmic endogenous levels of melatonin for several weeks until they start their own pineal rhythm of melatonin production at approximately 2 weeks of life. During pregnancy, daily rhythmic transfer of maternal melatonin to the fetus has important physiological roles in sheep, nonhuman primates, and rats. This melatonin rhythm provides a circadian signal and also participates in adjusting the physiology of several organs in preparation for extrauterine life. We propose that the ensuing absence of a melatonin rhythm plays a role in neonatal adaptation. To test this hypothesis, we studied the effects of imposing a high-amplitude melatonin rhythm in the newborn lamb on (1) clock time-related changes in cortisol and plasma variables and (2) clock time-related changes of gene expression of clock genes and selected functional genes in the adrenal gland and heart. We treated newborn lambs with a daily oral dose of melatonin (0.25 mg/kg) from birth to 5 days of age, recreating a high-amplitude melatonin rhythm. This treatment suppressed clock time-related changes of plasma adrenocorticotropic hormone, cortisol, clock gene expression, and functional genes in the newborn adrenal gland. In the heart, it decreased heart/body weight ratio, increased expression of Anp and Bnp, and resulted in different heart gene expression from control newborns. The interference of this postnatal melatonin treatment with the normal postnatal pattern of adrenocortical function and heart development support a physiological role for the window of flat postnatal melatonin levels during the neonatal transition.

Asunto(s)

Glándulas Suprarrenales/metabolismo , Ritmo Circadiano/fisiología , Melatonina/sangre , Miocardio/metabolismo , Glándulas Suprarrenales/efectos de los fármacos , Animales , Animales Recién Nacidos , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Femenino , Expresión Génica/efectos de los fármacos , Corazón/efectos de los fármacos , Corazón/fisiología , Masculino , Melatonina/farmacología , Melatonina/fisiología , Péptido Natriurético Encefálico/genética , Proteínas Circadianas Period/genética , Ovinos

RESUMEN

BACKGROUND: The selective estrogen receptor modulators (SERMs) raloxifene and tamoxifen are used for the treatment of osteoporosis and cancer, respectively, in women. The impairment of both the Atrial Natriuretic Peptide (ANP) cell signaling system and the translocation of nuclear factor-kappa B (NF-kB) to the cell nucleus are associated with detrimental cardiovascular effects and inflammation. The effects of SERMs on these parameters in the cardiac tissue of estrogen-deficient rats has not been reported. METHODS: We investigated the effects of raloxifene and tamoxifen on ANP signaling, p65 NF-kB nuclear translocation, cardiac histology and contractility. Female rats were divided into five groups: control (SHAM), ovariectomized (OVX), OVX-treated 17-ß-estradiol (E), OVX-treated raloxifene (RLX) and OVX-treated tamoxifen (TAM). The treatments started 21days after ovariectomy and continued for 14days. RESULTS: Ovariectomy reduced ANP mRNA in the left atrium (LA), decreased the content of ANP protein in the LA and in plasma, and increased the level of p65 NF-kB nuclear translocation in the left ventricle. Both 17-ß-estradiol and SERMs were able to reverse these alterations, which were induced by the estrogen deficient state. The hemodynamic and cardiac structural parameters analyzed in the present work were not modified by the interventions. CONCLUSIONS: Our study demonstrates, for the first time, the additional benefits of raloxifene and tamoxifen in an estrogen-deficient state. These include the normalization of plasmatic and cardiac ANP levels and cardiac p65 NF-kB translocation. Therefore, these treatments promote cardiovascular protection and may contribute to the prevention of cardiac dysfunction observed long-term in postmenopausal women.

Asunto(s)

Factor Natriurético Atrial/metabolismo , Estrógenos/metabolismo , FN-kappa B/metabolismo , Clorhidrato de Raloxifeno/farmacología , Tamoxifeno/farmacología , Transporte Activo de Núcleo Celular/efectos de los fármacos , Animales , Factor Natriurético Atrial/genética , Peso Corporal , Femenino , Corazón , Hemodinámica/efectos de los fármacos , Miocardio/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Ovariectomía , Ratas , Moduladores Selectivos de los Receptores de Estrógeno/farmacología , Útero/efectos de los fármacos

RESUMEN

Recent studies have evidenced the involvement of inflammation-related pathways to the development of cardiac hypertrophy and other consequences on the cardiovascular system, including the calcium-binding protein S100A8. However, this has never been investigated in the thyroid hormone (TH)-prompted cardiac hypertrophy. Thus, we aimed to test whether S100A8 and related signaling molecules, myeloid differentiation factor-88 (MyD88) and nuclear factor kappa B (NF-қB), could be associated with the cardiomyocyte hypertrophy induced by TH. Our results demonstrate that the S100A8/MyD88/NF-қB signaling pathway is activated in cardiomyocytes following TH stimulation. The knockdown of S100A8 and MyD88 indicates the contribution of those molecules to cardiomyocyte hypertrophy in response to TH, as evaluated by cell surface area, leucine incorporation assay, and gene expression. Furthermore, S100A8 and MyD88 are crucial mediators of NF-қB activation, which is also involved in the hypertrophic growth of TH-treated cardiomyocytes. Supporting the in vitro data, the contribution of NF-қB for TH-induced cardiac hypertrophy is confirmed in vivo, by using transgenic mice with cardiomyocyte-specific suppression of NF-қB. These data identify a novel pathway regulated by TH that mediates cardiomyocyte hypertrophy. However, the potential role of this new pathway in short and long-term cardiac effects of TH remains to be further investigated. KEY MESSAGES: Inflammation-related signaling is activated by T3 in cardiomyocytes. S100A8 and MyD88 have a crucial role in cardiomyocyte hypertrophy by T3. S100A8 and MyD88 mediate NF-қB activation by T3. NF-қB contributes to T3-induced cardiac hypertrophy in vitro and in vivo.

Asunto(s)

Calgranulina A/genética , Cardiomegalia/genética , Factor 88 de Diferenciación Mieloide/genética , FN-kappa B/genética , Triyodotironina , Animales , Factor Natriurético Atrial/genética , Células Cultivadas , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Péptido Natriurético Encefálico/genética , ARN Mensajero/metabolismo , ARN Interferente Pequeño/genética , Ratas Wistar , Transducción de Señal , Receptor Toll-Like 4/genética

RESUMEN

AIM: In this study, the effects of postnatal overfeeding on heart energy homoeostasis and cardiac haemodynamics in adult male Swiss mice were examined. METHODS AND RESULTS: During the suckling period, the mice were divided into four groups of control or overfed pups in combination with baseline or ischaemia/reperfusion treatments (control group baseline, CGBL; overfed group baseline, OGBL; control group ischaemia/reperfusion, CGIR; and overfed group ischaemia/reperfusion, OGIR). End diastolic pressure (EDP), heart contraction speed (Max dP/dt), relaxation speed (Min dP/dt), isovolumetric relaxation time (Tau) and frequency by beats per minute (BPM) were measured. During baseline and ischaemia/reperfusion, key proteins such as AKT1, AKT2, AKT3, pAKT, adenosine monophosphate-activated protein kinase (AMPK), pAMPK, insulin receptor beta (IRß), protein tyrosine phosphatase 1B (PTP1B), insulin receptor substrate 1 (IRS1), fatty acid binding protein (FABP), CD36, phosphoinositide 3-kinase (PI3K) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) were studied. The expression of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), carnitine palmitoyltransferase 1 (CPT1) and uncoupling protein 3 (UCP3) was studied as a marker of cardiac hypertrophy and energetic metabolism. Cardiac fibrosis was analyzed by quantifying collagen deposition, which is increased in the OGBL and OGIR groups compared with the control groups. CONCLUSIONS: The OGBL group showed reduced EDP compared with the CGBL group and high Max dP/dt compared with the OGBL group. Ischaemia/reperfusion increased EDP and Min dP/dt in the intragroup comparison. By contrast, Tau and frequency were not significantly different among groups. The OGIR mice showed significant alterations in heart metabolism proteins, including AKT2, pAKT/AKT1, pAKT/AKT2, AMPK, pAMPK/AMPK, PTP1B, IRS1, FABP and CD36. Furthermore, alterations in ANP, BNP, CPT1 and UCP3 messenger RNA (mRNA) expression indicated hypertrophy and reduction in their efficiency, such that exclusive overnutrition in childhood induces a long-term effect on haemodynamics, metabolism and heart remodelling.

Asunto(s)

Insuficiencia Cardíaca/etiología , Lactancia , Hipernutrición/complicaciones , Animales , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Presión Sanguínea , Femenino , Insuficiencia Cardíaca/metabolismo , Hemodinámica , Proteínas Sustrato del Receptor de Insulina/genética , Proteínas Sustrato del Receptor de Insulina/metabolismo , Grasa Intraabdominal/metabolismo , Canales Iónicos/genética , Canales Iónicos/metabolismo , Masculino , Ratones , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Contracción Miocárdica , Miocitos Cardíacos/metabolismo , Hipernutrición/metabolismo , PPAR gamma/genética , PPAR gamma/metabolismo , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/metabolismo , Atención Posnatal , Proteína Tirosina Fosfatasa no Receptora Tipo 1/genética , Proteína Tirosina Fosfatasa no Receptora Tipo 1/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Proteína Desacopladora 3

Asunto(s)

Animales , Ratas , Factor Natriurético Atrial/metabolismo , Calcio/farmacología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/enzimología , Poli(ADP-Ribosa) Polimerasas/metabolismo , Angiotensina II/farmacología , Animales Recién Nacidos , Factor Natriurético Atrial/genética , Calcio/metabolismo , Activación Enzimática/efectos de los fármacos , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , /metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Contracción Miocárdica/efectos de los fármacos , Fosforilación/efectos de los fármacos , Regiones Promotoras Genéticas/genética , Unión Proteica/efectos de los fármacos , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , Ratas Sprague-Dawley , Ribosa/metabolismo

RESUMEN

Sulforaphane is a naturally occurring isothiocyanate capable of stimulating cellular antioxidant defenses and inducing phase 2 detoxifying enzymes, which can protect cells against oxidative damage. Oxidative stress and apoptosis are intimately involved in the pathophysiology of cardiac diseases. Although sulforaphane is known for its anticancer benefits, its role in cardiac cells is just emerging. The aim of the present study was to investigate whether sulforaphane can modulate oxidative stress, apoptosis, and correlate with PGC-1α, a transcriptional cofactor involved in energy metabolism. H9c2 cardiac myoblasts were incubated with R-sulforaphane 5 µmol/L for 24 h. Cell viability, ANP gene expression, oxidative stress and apoptosis markers, and protein expression of PGC-1α were studied. In cells treated with sulforaphane, cellular viability increased (12 %) and ANP gene expression decreased (46 %) compared to control cells. Moreover, sulforaphane induced a significant increase in superoxide dismutase (103 %), catalase (101 %), and glutathione S-transferase (72 %) activity, reduced reactive oxygen species levels (15 %) and lipid peroxidation (65 %), as well as stimulated the expression of the cytoprotective enzyme heme oxygenase-1 (4-fold). Sulforaphane also promoted an increase in the expression of the anti-apoptotic protein Bcl-2 (60 %), decreasing the Bax/Bcl-2 ratio. Active Caspase 3\7 and p-JNK/JNK were also reduced by sulforaphane, suggesting a reduction in apoptotic signaling. This was associated with an increased protein expression of PGC-1α (42 %). These results suggest that sulforaphane offers cytoprotection to cardiac cells by activating PGC1-α, reducing oxidative stress, and decreasing apoptosis signaling.

Asunto(s)

Antioxidantes/farmacología , Isotiocianatos/farmacología , Mioblastos Cardíacos/efectos de los fármacos , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Animales , Apoptosis , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Línea Celular , Supervivencia Celular/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Mioblastos Cardíacos/fisiología , Estrés Oxidativo/efectos de los fármacos , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Ratas , Transducción de Señal/efectos de los fármacos , Sulfóxidos

RESUMEN

BACKGROUND: The compensatory actions of the endogenous natriuretic peptide system require adequate processing of natriuretic peptide pro­hormones into biologically active, carboxyl­terminal fragments. Natriuretic peptide pro­peptide processing is accomplished by corin, a transmembrane serine protease expressed by cardiomyocytes. Brain natriuretic peptide (BNP) processing is inadequate in advanced heart failure and is independently associated with adverse outcomes; however, the molecular mechanisms causing impaired BNP processing are not understood. We hypothesized that the development of endoplasmic reticulum stress in cardiomyocytes in advanced heart failure triggers inositol­requiring protein 1 (IRE1)­dependent corin mRNA decay, which would favor a molecular substrate favoring impaired natriuretic peptide pro­peptide processing. METHODS AND RESULTS: Two independent samples of hearts obtained from patients with advanced heart failure at transplant demonstrated that corin RNA was reduced as Atrial natriuretic peptide (ANP)/BNP RNA increased. Increases in spliced X­box protein 1, a marker for IRE1­endoribonuclease activity, were associated with decreased corin RNA. Moreover, ≈50% of the hearts demonstrated significant reductions in corin RNA and protein as compared to the nonfailing control sample. In vitro experiments demonstrated that induction of endoplasmic reticulum stress in cultured cardiomyocytes with thapsigargin activated IRE1's endoribonuclease activity and time­dependent reductions in corin mRNA. In HL­1 cells, overexpression of IRE1 activated IRE1 endoribonuclease activity and caused corin mRNA decay, whereas IRE1­RNA interference with shRNA attenuated corin mRNA decay after induction of endoplasmic reticulum stress with thapsigargin. Pre­treatment of cells with Actinomycin D to inhibit transcription did not alter the magnitude or time course of thapsigargin­induced corin mRNA decline, supporting the hypothesis that this was the result of IRE1­mediated corin mRNA degradation. CONCLUSIONS: These data support the hypothesis that endoplasmic reticulum stress­mediated, IRE1­dependent targeted corin mRNA decay is a mechanism leading to corin mRNA resulting in corresponding corin protein deficiency may contribute to the pathophysiology of impaired natriuretic peptide pro­hormone processing in humans processing in humans with advanced systolic heart failure.

Asunto(s)

Endorribonucleasas/metabolismo , Insuficiencia Cardíaca/enzimología , Miocardio/enzimología , Proteínas Serina-Treonina Quinasas/metabolismo , Estabilidad del ARN , ARN Mensajero/metabolismo , Serina Endopeptidasas/deficiencia , Animales , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Regulación hacia Abajo , Retículo Endoplásmico/enzimología , Retículo Endoplásmico/patología , Estrés del Retículo Endoplásmico , Endorribonucleasas/genética , Perfilación de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Células HEK293 , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/fisiopatología , Humanos , Ratones , Miocardio/patología , Péptido Natriurético Encefálico/genética , Péptido Natriurético Encefálico/metabolismo , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismo , Proteínas Serina-Treonina Quinasas/genética , ARN Mensajero/genética , Factores de Transcripción del Factor Regulador X , Serina Endopeptidasas/genética , Transducción de Señal , Factores de Tiempo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transfección

RESUMEN

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.

Asunto(s)

Factor Natriurético Atrial/metabolismo , Regulación hacia Abajo , Estradiol/biosíntesis , Síndrome del Ovario Poliquístico/metabolismo , Testosterona/biosíntesis , Animales , Factor Natriurético Atrial/genética , Estradiol/administración & dosificación , Estradiol/análogos & derivados , Estradiol/metabolismo , Femenino , Inyecciones Subcutáneas , Síndrome del Ovario Poliquístico/inducido químicamente , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Testosterona/metabolismo

RESUMEN

BACKGROUND: The role of aldosterone blockers during transition from long-term compensated hypertrophy to dilated failure is not completely understood. In this study we evaluated the effects of early administration of spironolactone on cardiac remodeling, myocardial function, and mortality in spontaneously hypertensive rats (SHR). METHODS: Sixteen-month-old SHR received no treatment (SHR-C, n=72) or spironolactone (SHR-SPR, 20 mg/kg/day, n=34) for six months. Echocardiogram was performed before and after treatment. Myocardial function was analyzed in left ventricular (LV) papillary muscle preparations. Myocardial collagen and hydroxyproline concentration were evaluated by morphometry and spectrophotometry, respectively. LV gene expression was assessed by real time RT-PCR. STATISTICS: Student's t test; Log rank test (Kaplan Meyer). RESULTS: SHR-C and SHR-SPR presented mortality rates of 71 and 38%, respectively (p=0.004). Systolic arterial pressure did not differ between groups (SHR-C 199±43; SHR-SPR 200±35 mmHg). Initial and final echocardiograms did not show significant differences in cardiac structures or LV function between groups. Myocardial function was similar between groups at basal and after inotropic stimulation. Collagen fractional area, hydroxyproline concentration, gene expression for α- and ß-myosin heavy chain, atrial natriuretic peptide, and Serca2a were not different between groups. CONCLUSION: Early spironolactone administration reduces mortality without changing cardiac remodeling in spontaneous hypertensive rats.

Asunto(s)

Hipertensión/tratamiento farmacológico , Hipertensión/mortalidad , Antagonistas de Receptores de Mineralocorticoides/farmacología , Espironolactona/farmacología , Remodelación Ventricular/efectos de los fármacos , Aldosterona/metabolismo , Animales , Factor Natriurético Atrial/genética , Electrocardiografía , Regulación de la Expresión Génica/efectos de los fármacos , Hipertensión/fisiopatología , Masculino , Músculos Papilares/efectos de los fármacos , Músculos Papilares/fisiopatología , Ratas , Ratas Endogámicas SHR , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , Espironolactona/administración & dosificación , Función Ventricular Izquierda/efectos de los fármacos

RESUMEN

OBJECTIVE: The purpose of this study was to compare the effects of conjugated equine estrogens (CEE) and estradiol benzoate on the blood pressure and body weight of spontaneously hypertensive rats (SHRs) and the associated changes in several components of the natriuretic peptide system. METHODS: The blood pressure of randomly distributed female SHRs and Wistar rats was determined by tail plethysmography. The rats were ovariectomized and, after 3 weeks, injected daily for 4 days with estradiol benzoate (5 µg/100 g/d), CEE (50 µg/100 g/d), or vehicle (corn oil 0.1 mL/100 g/d). One day after the last injection, the rats were decapitated, and their blood was collected to measure atrial natriuretic peptide (ANP) and estradiol. The atria were removed to measure ANP levels using radioimmunoassay and to quantify ANP messenger RNA expression using real-time polymerase chain reaction. The kidneys and adipose tissue were removed to analyze the expression of natriuretic peptide clearance receptor messenger RNA. RESULTS: A reduction in blood pressure was observed in estradiol-treated SHRs, but CEE treatment had no effect. Estradiol decreased the body weight and parametrial adipose tissue mass of SHRs. Estradiol-induced alterations in SHRs were accompanied by increased synthesis and release of ANP. CEE had no effect on body weight but increased the mesenteric adipose tissue mass of SHRs. CONCLUSIONS: These results indicate that estradiol and CEE have different effects on the reduction in body weight and blood pressure. These results are correlated with changes in plasma ANP levels.

Asunto(s)

Presión Sanguínea/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Estradiol/análogos & derivados , Estrógenos Conjugados (USP)/farmacología , Estrógenos/farmacología , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Animales , Factor Natriurético Atrial/sangre , Factor Natriurético Atrial/genética , Estradiol/sangre , Estradiol/farmacología , Femenino , Expresión Génica , Atrios Cardíacos/metabolismo , Riñón/metabolismo , Mesenterio , Ovariectomía , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas SHR , Ratas Wistar , Receptores del Factor Natriurético Atrial/genética

RESUMEN

The aim of the present study was to verify the effects of low-intensity endurance training and detraining on the mechanical and molecular properties of cardiomyocytes from spontaneously hypertensive rats (SHRs). Male SHRs and normotensive control Wistar rats at 16-weeks of age were randomly divided into eight groups of eight animals: NC8 and HC8 (normotensive and hypertensive control for 8weeks); NT8 and HT8 (normotensive and hypertensive trained at 50-60% of maximal exercise capacity for 8weeks); NC12 and HC12 (normotensive and hypertensive control for 12weeks); NDT and HDT (normotensive and hypertensive trained for 8weeks and detrained for 4weeks). The total exercise time until fatigue (TTF) was determined by a maximal exercise capacity test. Resting heart rate (RHR) and systolic arterial pressure (SAP) were measured. After the treatments, animals were killed by cervical dislocation and left ventricular myocytes were isolated by enzymatic dispersion. Isolated cells were used to determine intracellular global Ca(2+) ([Ca(2+)]i) transient and cardiomyocyte contractility (1Hz; ~25°C). [Ca(2+)]i regulatory proteins were measured by Western blot, and the markers of pathologic cardiac hypertrophy by quantitative real-time polymerase chain reaction (q-RT-PCR). Exercise training augmented the TTF (NC8, 11.4±1.5min vs. NT8, 22.5±1.4min; HC8, 11.7±1.4min vs. HT8, 24.5±1.3min; P<0.05), reduced RHR (NT8initial, 340±8bpm vs. NT8final, 322±10bpm; HT8initial, 369±8bpm vs. HT8final, 344±10bpm; P<0.05), and SBP in SHR animals (HC8, 178±3mmHg vs. HT8, 161±4mmHg; P<0.05). HC8 rats showed a slower [Ca(2+)]i transient (Tpeak, 83.7±1.8ms vs. 71.7±2.4ms; T50%decay, 284.0±4.3ms vs. 264.0±4.1ms; P<0.05) and cell contractility (Vshortening, 86.1±6.7µm/s vs. 118.6±6.7µm/s; Vrelengthening, 57.5±7.4µm/s vs. 101.3±7.4µm/s; P<0.05), and higher expression of ANF (300%; P<0.05), skeletal α-actin (250%; P<0.05) and a decreased α/ß-MHC ratio (70%; P<0.05) compared to NC8. Exercise training increased [Ca(2+)]i transient (NC8, 2.39±0.06F/F0 vs. NT8, 2.72±0.06F/F0; HC8, 2.28±0.05F/F0 vs. HT8, 2.82±0.05F/F0; P<0.05), and cell contractility (NC8, 7.4±0.3% vs. NT8, 8.4±0.3%; HC8, 6.8±0.3% vs. HT8, 7.8±0.3%; P<0.05). Furthermore, exercise normalized the expression of ANF, skeletal α-actin, and the α/ß-MHC ratio in HT8 rats, augmented the expression of SERCA2a (NC8, 0.93±0.15 vs. NT8, 1.49±0.14; HC8, 0.83±0.13 vs. HT8, 1.32±0.14; P<0.05) and PLBser16 (NC8, 0.89±0.18 vs. NT8, 1.23±0.17; HC8, 0.77±0.17 vs. HT8, 1.32±0.16; P<0.05), and reduced PLBt/SERCA2a (NC8, 1.21±0.19 vs. NT8, 0.50±0.21; HC8, 1.38±0.17 vs. HT8, 0.66±0.21; P<0.05). However, all these adaptations returned to control values within 4weeks of detraining in both SHR and normotensive control animals. In conclusion, low-intensity endurance training induces positive benefits to left ventricular myocyte mechanical and molecular properties, which are reversed within 4weeks of detraining.

Asunto(s)

Hipertensión/terapia , Contracción Miocárdica , Miocitos Cardíacos/fisiología , Animales , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Señalización del Calcio , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Células Cultivadas , Terapia por Ejercicio , Expresión Génica , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/fisiopatología , Hipertensión/metabolismo , Hipertensión/fisiopatología , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/patología , Hipertrofia Ventricular Izquierda/fisiopatología , Masculino , Cadenas Pesadas de Miosina/metabolismo , Condicionamiento Físico Animal , Resistencia Física , Ratas , Ratas Endogámicas SHR , Ratas Wistar , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo

RESUMEN

Cardiovascular and immune system abnormalities have been reported in females with estrogen deficiency. To control these disorders in post-menopausal women, hormone replacement therapy (HRT) has been used. Tibolone has been used as a HRT, but the effects of tibolone on the natriuretic peptide system have not been determined. We investigated the effects of tibolone on the natriuretic peptide system and pro-inflammatory cytokines in ovariectomized (OVX) rats. Female rats were divided into four groups: SHAM, OVX, OVX treated with 17ß-estradiol (OVX+E: 14 days) and OVX treated with tibolone (OVX+T: 14 days) beginning 21 days after ovariectomy. On day 35, blood was collected to determine atrial natriuretic peptide (ANP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) levels. In addition, tissues were collected for determining ANP, natriuretic peptide receptor type-A (NPR-A), and NPR type-C (NPR-C) gene expression levels by RT-PCR. The cytokine levels of both IL-6 and TNF-α were increased in OVX animals. In comparison, IL-6 and TNF-α levels were reduced in OVX+E animals. TNF-α levels were reduced similarly in OVX+T animals, but IL-6 levels remained elevated in this group. The concentrations of ANP in the left atrium tissue and plasma were decreased after ovariectomy, as were ANP mRNA levels in the left atrium and NPR-A mRNA levels in kidney. No variation in NPR-C gene expression in the kidney tissue was observed among the groups. Tibolone and 17ß-estradiol effectively increased plasma ANP and ANP mRNA levels in the left atrium, but did not normalize renal NPR-A levels. Since HRT with tibolone normalizes plasma ANP and serum TNF-alpha levels our results suggest that treatment with tibolone has anti-inflammatory effects and could prevent cardiovascular disease in the long-term.

Asunto(s)

Factor Natriurético Atrial/metabolismo , Estrógenos/deficiencia , Terapia de Reemplazo de Hormonas/métodos , Norpregnenos/uso terapéutico , Receptores del Factor Natriurético Atrial/metabolismo , Factor de Necrosis Tumoral alfa/sangre , Animales , Antiinflamatorios/uso terapéutico , Factor Natriurético Atrial/sangre , Factor Natriurético Atrial/genética , Enfermedades Cardiovasculares/tratamiento farmacológico , Estradiol/farmacología , Femenino , Atrios Cardíacos/metabolismo , Atrios Cardíacos/patología , Frecuencia Cardíaca/efectos de los fármacos , Interleucina-6/sangre , Riñón/metabolismo , Tamaño de los Órganos , Ovariectomía/métodos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores del Factor Natriurético Atrial/genética , Útero/efectos de los fármacos , Útero/metabolismo , Útero/patología

RESUMEN

BACKGROUND: The atrial natriuretic peptide (ANP) is known mainly for its effects on kidney function and blood pressure homeostasis. We investigated the association between two ANP polymorphisms and pre-existing coronary artery disease (CAD) in patients of African descent with type 2 diabetes (T2D). METHODS: We conducted a cross-sectional and retrospective study of 218 volunteer Afro-Caribbean patients with T2D. Two polymorphisms (rs5064, 708C>T; and rs5065, 2238T>C) of ANP were genotyped using PCR-restriction fragment length polymorphism analysis. ANCOVA, χ2-test, and logistic regression were used for statistical analysis. RESULTS: Among these patients (92 men; 128 women), 67 (30.7%) had CAD, of whom 75% had had myocardial infarction. The frequency of rs5065-C carriers (TC/CC) was significantly lower in patients with CAD than in those without CAD (24 vs. 41%, P = 0.01). The frequency of hypertension did not differ significantly according to genotype. Univariate logistic regression revealed that male sex, age, dyslipidemia, hypertension, and rs5065-C carrier status were associated significantly with CAD. After adjustment for the variables of interest, the odds ratio (ORs) of CAD for rs5065-C carriers (TC/CC) was 0.50 (0.26-0.96; P = 0.038). No association was found between the rs5064 (708C>T) single-nucleotide polymorphisms (SNPs) and pre-existing CAD or cardiovascular risk factors. CONCLUSIONS: The ANP rs5065 (2238T>C) C allele seems to exert a protective effect against CAD in T2D patients of African descent. The relevance of ANP polymorphisms for CAD should be determined in different populations.

Asunto(s)

Factor Natriurético Atrial/genética , Población Negra/genética , Enfermedad de la Arteria Coronaria/genética , Diabetes Mellitus Tipo 2/genética , Polimorfismo de Nucleótido Simple/genética , Anciano , Población Negra/etnología , Enfermedades Cardiovasculares/epidemiología , Comorbilidad , Enfermedad de la Arteria Coronaria/epidemiología , Enfermedad de la Arteria Coronaria/etnología , Estudios Transversales , Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/etnología , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Análisis de Regresión , Estudios Retrospectivos , Factores de Riesgo , Indias Occidentales

RESUMEN

The aim of this study was to compare, under resting conditions, the influence of chronic training in swimming or running on mean arterial pressure (MAP) and the involvement of the natriuretic peptide system in this response. Two-month-old male spontaneously hypertensive rats (SHR) were divided into three groups-sedentary (SD), swimming (SW) and running (RN)-and were trained for eight weeks under regimens of similar intensities. Atria tissue and plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay. ANP mRNA levels in the right and left atria as well as the natriuretic peptide receptors (NPR), NPR-A and NPR-C, mRNA levels in the kidney were determined by real-time PCR. Autoradiography was used to quantify NPR-A and NPR-C in mesenteric adipose tissue. Both training modalities, swimming and running, reduced the mean arterial pressure (MAP) of SHR. Swimming, but not running, training increased plasma levels of ANP compared to the sedentary group (P<0.05). Expression of ANP mRNA in the left atrium was reduced in the RN compared to the SD group (P<0.05). Expression of NPR-A and NPR-C in the kidneys of the SW group decreased significantly (P<0.05) compared to the SD group. Although swimming increased (125)I-ANP binding to mesenteric adipose tissue, displacement by c-ANF was reduced, indicating a reduction of NPR-C. These results suggest that the MAP reduction induced by exercise in SHR differs in its mechanisms between the training modalities, as evidenced by the finding that increased levels of ANP were only observed after the swimming regimen.

Asunto(s)

Arterias/fisiología , Factor Natriurético Atrial/metabolismo , Presión Sanguínea/fisiología , Condicionamiento Físico Animal/fisiología , Animales , Factor Natriurético Atrial/genética , Masculino , Ratas , Ratas Endogámicas SHR , Receptores del Factor Natriurético Atrial/genética , Receptores del Factor Natriurético Atrial/metabolismo , Carrera , Natación

RESUMEN

The present study was designed to develop an animal model of hypertension and cardiac hypertrophy associated with obesity in female rats. Furthermore, we studied the involvement of the natriuretic peptide system in the mechanisms of these conditions. Obesity was induced in Wistar rats by a high fat diet and ovariectomy. The rats were divided into four groups: ovariectomized or sham-operated with high-fat diet and ovariectomized or sham-operated with control diet. After 24 weeks of diet, rats were killed, and their tissues were removed. Cardiac atrial natriuretic peptide (ANP), clearance receptor (NPr-C) gene expression was determined by PCR. ANP concentrations were measured in plasma. Ovariectomized fat-fed rats (OF) showed increased body weight, visceral fat depot and blood pressure and decreased sodium excretion compared to other groups. Also, these rats showed higher heart-to-body weight and cell diameters of ventricular cardiomyocytes and lower cardiac ANP mRNA and plasma ANP than the control group. The adipocyte and renal NPr-C mRNA of OF rats were higher than the control group. These data showed that combined ovariectomy and high fat diet elicited obesity, hypertension and cardiac hypertrophy. These results suggest that the impairment of the natriuretic peptide system may be one of the mechanisms involved not only in development of hypertension but also in cardiac hypertrophy associated with obesity in ovariectomized rats.

Asunto(s)

Factor Natriurético Atrial/sangre , Cardiomegalia/sangre , Hipertensión/sangre , Obesidad/sangre , Receptores del Factor Natriurético Atrial/sangre , Animales , Factor Natriurético Atrial/genética , Presión Sanguínea , Cardiomegalia/complicaciones , Cardiomegalia/fisiopatología , Dieta , Grasas de la Dieta/efectos adversos , Grasas de la Dieta/metabolismo , Modelos Animales de Enfermedad , Femenino , Expresión Génica , Corazón/fisiopatología , Hipertensión/complicaciones , Hipertensión/fisiopatología , Grasa Intraabdominal/patología , Obesidad/complicaciones , Obesidad/fisiopatología , Tamaño de los Órganos , Ovariectomía/efectos adversos , Ovario , ARN Mensajero/análisis , Ratas , Ratas Wistar , Receptores del Factor Natriurético Atrial/genética , Sodio/orina

RESUMEN

The hemodynamic and cardiac effects of isoproterenol were examined in rats submitted to chronic salt loading (1% NaCl as drinking water) to prevent activation of the systemic renin-angiotensin system. Isoproterenol treatment for 1 week resulted in 36% and 44% (P<0.05) increase in left ventricle mass in both control and chronic salt loading rats and induction of cardiac angiotensin-converting enzyme activity and expression (P<0.05) with no changes in serum angiotensin-converting enzyme. Plasma renin activity decreased significantly with chronic salt loading and failed to increase by isoproterenol treatment, whereas it increased 2.33 fold (P<0.05) in animals kept on regular chow. Isoproterenol treatment leads to transient increase in heart rate and cardiac output while blood pressure remained unchanged. Altogether, these data provide evidence that isoproterenol induced hypertrophy is associated with cardiac induction of angiotensin-converting enzyme and daily transient hemodynamic overload even in the absence of systemic activation of renin-angiotensin system.

Asunto(s)

Agonistas Adrenérgicos beta/farmacología , Hipertrofia Ventricular Izquierda/fisiopatología , Isoproterenol/farmacología , Sistema Renina-Angiotensina/efectos de los fármacos , Agonistas Adrenérgicos beta/administración & dosificación , Animales , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Gasto Cardíaco/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Hipertrofia Ventricular Izquierda/inducido químicamente , Isoproterenol/administración & dosificación , Masculino , Miocardio/enzimología , Peptidil-Dipeptidasa A/genética , Peptidil-Dipeptidasa A/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Renina/sangre , Sistema Renina-Angiotensina/fisiología , Cloruro de Sodio Dietético , Regulación hacia Arriba

RESUMEN

Long-term nitric oxide (NO) blockade is known to induce a severe and progressive hypertension. The influence of the salt-intake on atrial natriuretic peptide (ANP) system in this hypertension model is unknown. The aim of this study was to evaluate ANP plasma levels, content and mRNA in atria of male Wistar rats chronically treated with oral Nomega-nitro-L-arginine methyl ester (L-NAME) after 4 weeks of high-salt diet. The high-salt diet induced an increase (P < 0.05) in ANP plasma levels in normotensive rats and no significant changes in hypertensive animals. We observed a significant increase in the ANP content in the left and right atria of hypertensive rats (P < 0.001) when compared to normotensive ones. However, no significant changes were observed during high-salt diet in normotensive and hypertensive animals. Northern blot analysis revealed that ANP gene expression is higher in the right and left atria of hypertensive rats when compared to normotensive rats. However, we found no significant changes in ANP mRNA of rats treated with high-salt diet in normotensive and hypertensive rats when compared to low-salt diet. The present observations indicate no interaction between salt-intake and activation of the ANP system during chronic nitric oxide synthase (NOS) inhibition.

Asunto(s)

Factor Natriurético Atrial/sangre , Hipertensión/sangre , Óxido Nítrico/antagonistas & inhibidores , Cloruro de Sodio Dietético/farmacología , Animales , Factor Natriurético Atrial/genética , Presión Sanguínea/efectos de los fármacos , Northern Blotting , Inhibidores Enzimáticos/farmacología , Atrios Cardíacos/efectos de los fármacos , Hipertensión/fisiopatología , Masculino , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa/antagonistas & inhibidores , ARN Mensajero/genética , Ratas , Ratas Wistar

RESUMEN

The aim of the present study was to determine the involvement of atrial natriuretic peptide (ANP) in blood pressure (BP) alterations induced by estradiol treatment. Spontaneously hypertensive rats (SHR) and Wistar rats (WR) were ovariectomized and, after 3 weeks, were injected daily for 4 days with estradiol benzoate (E2; 5 microg/100 g/day) or a vehicle. One day after the last injection, the animals were decapitated, blood was collected, and both right and left atrial appendages were quickly removed for determination of ANP by radioimmunoassay (RIA), or used for ANP mRNA determination. Estradiol treatment induced a significant reduction of blood pressure in SHR, but not in WR. This reduction was correlated with the increase of plasma ANP levels that were significantly increased in E2-treated, compared with vehicle-treated, SHR. E2-treated SHR showed significant increases in ANP concentration in the right and left atria compared to the vehicle-treated animals. These observations were confirmed by ANP mRNA. In summary, the present study shows that short-term estradiol treatment reduces the blood pressure of ovariectomized SHR, but not of WR. This reduction was highly correlated with increased plasma estradiol and ANP levels. These results suggest that ANP is involved in mediating the effect of estradiol on blood pressure reduction.

Asunto(s)

Factor Natriurético Atrial/fisiología , Presión Sanguínea/efectos de los fármacos , Estradiol/análogos & derivados , Estradiol/farmacología , Animales , Antihipertensivos/farmacología , Factor Natriurético Atrial/genética , Presión Sanguínea/fisiología , Femenino , Péptido Natriurético Encefálico/fisiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Radioinmunoensayo , Ratas , Ratas Endogámicas SHR , Ratas Wistar

RESUMEN

AIMS/HYPOTHESIS: In case-control studies, polymorphisms at the atrial natriuretic peptide gene (ANP) locus have been associated with presence of albuminuria in Type 1 and Type 2 diabetes. We evaluated the relationship between the ScaIand BstxI polymorphisms and albuminuria in the general population of the Mexico City Diabetes Study. METHODS: Allele/genotype frequencies were analysed by PCR-RFLP analysis using ScaI (wild, A(2) vs mutated, A(1)) and BstxI (wild, C(708) vs mutated, T(708)) enzyme. RESULTS: Among 1288 subjects, hypertension was present in 112 subjects, Type 2 diabetes in 191 and impaired glucose tolerance in 136; microalbuminuria was present in 464 subjects, and clinical proteinuria in 199. General frequencies were 0.93 and 0.96 for the wild alleles, and 0.07 and 0.04 for the mutated alleles, respectively for ScaI and BstxI. Frequency of A(1)was 0.08 in normoalbuminuric, 0.05 in microalbuminuric, and 0.05 in proteinuric patients (chi(2)=7.3, p=0.025). Frequency of T(708) was 0.06 in normoalbuminuric and 0.03 microalbuminuric and 0.03 in proteinuric subjects (chi(2)=8.1, p=0.017). By multivariate analysis, the associations between A(1)or T(708) allele and albuminuria were independent of age, sex, BMI, diabetes, and hypertension, (odds ratio (OR) 0.60, p=0.01, (OR) 0.51, p=0.004, respectively). CONCLUSION/INTERPRETATION: In the general population of Mexico City, both polymorphisms of ANP are associated with albuminuria independently of hypertension, and could play a role in protecting subjects against development of albuminuria.

Asunto(s)

Factor Natriurético Atrial/genética , Complicaciones de la Diabetes , Diabetes Mellitus/genética , Polimorfismo Genético/genética , Proteinuria/genética , Adulto , Albuminuria/epidemiología , Albuminuria/genética , Alelos , Desoxirribonucleasas de Localización Especificada Tipo II/genética , Diabetes Mellitus/epidemiología , Femenino , Frecuencia de los Genes , Intolerancia a la Glucosa/genética , Humanos , Hipertensión/epidemiología , Hipertensión/genética , Masculino , México/epidemiología , Persona de Mediana Edad , Población , Proteinuria/epidemiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa