natriuretic-peptide--brain and Hypertrophy

Magnesium isoglycyrrhizinate (MgIG) is a magnesium salt of the 18-α glycyrrhizic acid stereoisomer that has exhibited hepato-protective effects and has anti-inflammatory, antioxidant, and antiviral activities. Here, we have investigated the effects and potential mechanisms of action of MgIG, with respect to myocardial fibrosis induced by isoproterenol (ISO) in mice. Mice were administered MgIG for 14days, with concurrent ISO dosing, and were sacrificed two weeks later. Lactate dehydrogenase (LDH) and creatine kinase (CK) concentrations were measured in the blood. Pathological changes in the myocardium were observed via light microscopy. In addition, the expression of the Bax and Bcl-2 genes, and the basic fibroblast growth factor (bFGF) protein were measured via an immunohistochemical method. The RNA expression of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), c-fos, and c-jun mRNA were quantified by reverse transcription-polymerase chain reaction (RT-PCR) in the myocardial tissue. The protein expression of toll-like receptor (TLR) 4, and nuclear factor kappa B (NF-κB) (p65) were measured using Western blot assays. Compared with the control group, the ISO group showed significant increases in bFGF, Bax, Bcl-2, TLR4, and NF-κB (p65) expressions, as well as increased serum levels of LDH and CK. MgIG had a protective effect on ISO-induced myocardial fibrosis, which might be ascribed, at least in part, to the inhibition of the TLR4/NF-κB (p65) signaling pathway.

Topics: Animals; Anti-Inflammatory Agents; Atrial Natriuretic Factor; bcl-2-Associated X Protein; Creatine Kinase; Disease Models, Animal; Fibroblast Growth Factor 2; Fibrosis; Heart Diseases; Humans; Hypertrophy; Isoproterenol; L-Lactate Dehydrogenase; Mice; Mice, Inbred Strains; Myocardium; Natriuretic Peptide, Brain; NF-kappa B; Proto-Oncogene Proteins c-bcl-2; Saponins; Toll-Like Receptor 4; Triterpenes

The natriuretic peptides (NPs), through their diuretic, vasodilatory and anti-mitogenic properties, play an important role in the regulation of cardiovascular, renal and endocrine homeostasis. Recent studies suggest that they have utility in both the diagnosis and management of heart failure. Plasma brain NP (BNP) levels have been used to establish prognosis in patients with heart failure and those at risk for heart failure post-myocardial infarction. They have been used to establish a cardiac etiology for acute shortness of breath, and to guide and assess the efficacy of therapy in patients with established heart failure. BNP is also approved for use in the management of acute decompensated heart failure. Of note, recent studies suggest that cardiac NPs suppress myocyte hypertrophy and interstitial fibrosis in the heart, arguing for an important autocrine-paracrine role of these peptides in controlling the cardiac response during hypertrophy. Therefore, the existing evidence supports a role for BNP as both a marker and a modulator of hypertrophy.

Topics: Atrial Natriuretic Factor; Biomarkers; Cardiomyopathy, Dilated; Gene Expression Regulation; Humans; Hypertrophy; Myocardium; Natriuretic Peptide, Brain; Natriuretic Peptides

The natriuretic peptides (NPs) constitute a family of polypeptide hormones that regulate mammalian blood volume and blood pressure. The ability of the NPs to modulate cardiac hypertrophy and cell proliferation as well is now beginning to be recognized. The NPs interact with three membrane-bound receptors, all of which contain a well-characterized extracellular ligand-binding domain. The R1 subclass of NP receptors (NPR-A and NPR-B) contains a C-terminal guanylyl cyclase domain and is responsible for most of the NPs downstream actions through their ability to generate cGMP. The R2 subclass lacks an obvious catalytic domain and functions primarily as a clearance receptor. This review focuses on the signal transduction pathways initiated by ligand binding and other factors that help to determine signalling specificities, including allosteric factors modulating cGMP generation, receptor desensitization, the activation and function of cGMP-dependent protein kinase (PKG), and identification of potential nuclear or cytoplasmic targets such as the mitogen-activated protein kinase signalling (MAPK) cascade. The inhibition of cardiac growth and hypertrophy may be an important but underappreciated action of the NP signalling system.

Topics: Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Catalytic Domain; Cell Division; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cytoplasm; Guanylate Cyclase; Humans; Hypertrophy; Ligands; MAP Kinase Signaling System; Models, Biological; Molecular Sequence Data; Natriuretic Peptide, Brain; Protein Binding; Protein Structure, Tertiary; Receptors, Atrial Natriuretic Factor; Signal Transduction

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones located in atria granules. Both peptides respond to cardiac pressure and volume dynamics and accordingly serve as translation biomarkers for the clinical treatment of heart failure. Serum ANP and BNP play central secretary roles in blood pressure and cardiac output regulation and have proven utility as differential biomarkers of cardiovascular proficiency and drug-induced maladaptation, yet both peptides are impervious to exercise-induced hypertrophy. We employed immunoelectron microscopy to examine the effects of 28 days of chronic swim exercise or administration of a PPARγ agonist on atrial granules and their stored natriuretic peptides in Sprague Dawley rats. Chronic swimming and drug treatment both resulted in a 15% increase in heart weight compared with controls, with no treatment effects on perinuclear granule area in the left atria (LAs). Drug treatment resulted in larger size granules with greater BNP density in the right atria. Comparing swimming and PPARγ agonist treatment effects on ANP:BNP granule density ratios between atrial chambers revealed a shift toward a greater proportion of ANP than BNP in LAs of swim-trained rats. These data suggest a distinction in the population of ANP and BNP after chronic swim or PPARγ that makes it a novel metric for the differentiation of pathological and physiological hypertrophy.

Topics: Animals; Atrial Natriuretic Factor; Biomarkers; Heart Atria; Hypertrophy; Natriuretic Peptide, Brain; Peptides; PPAR gamma; Rats; Rats, Sprague-Dawley

Oxidized low-density lipoprotein (ox-LDL) is a type of modified cholesterol that promotes apoptosis and inflammation and advances the progression of heart failure. Leucine-zipper and sterile-α motif kinase (ZAK) is a kinase of the MAP3K family which is highly expressed in the heart and encodes two variants, ZAKα and ZAKβ. Our previous study serendipitously found opposite effects of ZAKα and ZAKβ in which ZAKβ antagonizes ZAKα-induced apoptosis and hypertrophy of the heart. This study aims to test the hypothesis of whether ZAKα and ZAKβ are involved in the damaging effects of ox-LDL in the cardiomyoblast. Cardiomyoblast cells H9c2 were treated with different concentrations of ox-LDL. Cell viability and apoptosis were measured by MTT and TUNEL assay, respectively. Western blot was used to detect apoptosis, hypertrophy, and pro-survival signaling proteins. Plasmid transfection, pharmacological inhibition with D2825, and siRNA transfection were utilized to upregulate or downregulate ZAKβ, respectively. Ox-LDL concentration-dependently reduces the viability and expression of several pro-survival proteins, such as phospho-PI3K, phospho-Akt, and Bcl-xL. Furthermore, ox-LDL increases cleaved caspase-3, cleaved caspase-9 as indicators of apoptosis and increases B-type natriuretic peptide (BNP) as an indicator of hypertrophy. Overexpression of ZAKβ by plasmid transfection attenuates apoptosis and prevents upregulation of BNP. Importantly, these effects were abolished by inhibiting ZAKβ either by D2825 or siZAKβ application. Our results suggest that ZAKβ upregulation in response to ox-LDL treatment confers protective effects on cardiomyoblast.

Topics: Animals; Apoptosis; Hypertrophy; Lipoproteins, LDL; Natriuretic Peptide, Brain; Protein Kinases; Rats; Up-Regulation

Clinical studies have indicated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, can potentially inhibit chronic heart failure. In the Stat-LVDF study, a difference was noted in terms of the effect of lipophilic pitavastatin (PTV) and hydrophilic rosuvastatin (RSV) on plasma BNP, suggesting that statin lipophilicity and pharmacokinetics change the pleiotropic effect on heart failure in humans. Therefore, we assessed the beneficial effects of PTV on hypertrophy in cardiac myocytes compared with RSV at clinically used doses. Cultured cardiomyocytes were stimulated with 30 μM phenylephrine (PE) in the presence of PTV (250 nM) or RSV (50 nM). These doses were calculated based on the maximum blood concentration of statins used in clinical situations in Japan. The results showed that PTV, but not RSV, significantly inhibits the PE-induced increase in cell size and leucine incorporation without causing cell toxicity. In addition, PTV significantly suppressed PE-induced mRNA expression of hypertrophic response genes. PE-induced ERK phosphorylation was inhibited by PTV, but not by RSV. Furthermore, PTV significantly suppressed the angiotensin-II-induced proline incorporation in primary cultured cardiac fibroblasts. In conclusion, a clinical dose of PTV was noted to directly inhibit cardiomyocyte hypertrophy and cardiac fibrosis, suggesting that lipophilic PTV can be a potential drug candidate against chronic heart failure.

Topics: Actins; Animals; Atrial Natriuretic Factor; Cells, Cultured; Extracellular Signal-Regulated MAP Kinases; Gene Expression; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertrophy; Leucine; Myocytes, Cardiac; Natriuretic Peptide, Brain; Phosphorylation; Quinolines; Rats, Sprague-Dawley; RNA, Messenger; Rosuvastatin Calcium

Metabolic shift is an important contributory factor for progression of hypertension-induced left ventricular hypertrophy into cardiac failure. Under hypertrophic conditions, heart switches its substrate preference from fatty acid to glucose. Prolonged dependence on glucose for energy production has adverse cardiovascular consequences. It was reported earlier that reactivation of fatty acid metabolism with medium chain triglycerides ameliorated cardiac hypertrophy, oxidative stress and energy level in spontaneously hypertensive rat. However, the molecular mechanism mediating the beneficial effect of medium chain triglycerides remained elusive. It was hypothesized that reduction of cardiomyocyte hypertrophy by medium chain fatty acid (MCFA) is mediated by modulation of signaling pathways over expressed in cardiac hypertrophy. The protective effect of medium chain fatty acid (MCFA) was evaluated in cellular model of myocyte hypertrophy. H9c2 cells were stimulated with Arginine vasopressin (AVP) for the induction of hypertrophy. Cell volume and secretion of brain natriuretic peptide (BNP) were used for assessment of cardiomyocyte hypertrophy. Cells were pretreated with MCFA (Caprylic acid) and metabolic modulation was assessed from the expression of medium-chain acyl-CoA dehydrogenase (MCAD), cluster of differentiation-36 (CD36) and peroxisome proliferator-activated receptor (PPAR)-α mRNA. The signaling molecules modified by MCFA was evaluated from protein expression of mitogen activated protein kinases (MAPK: ERK1/2, p38 and JNK) and Calcineurin A. Pretreatment with MCFA stimulated fatty acid metabolism in hypertrophic H9c2, with concomitant reduction of cell volume and BNP secretion. MCFA reduced activated ERK1/2, JNK and calicineurin A expression mediated by AVP. In conclusion, the beneficial effect of MCFA is possibly mediated by stimulation of fatty acid metabolism and modulation of MAPK and Calcineurin A.

Topics: Animals; Calcineurin; Caprylates; Cardiomegaly; CD36 Antigens; Cell Line; Fatty Acids; Glucose; Hypertension; Hypertrophy; Hypertrophy, Left Ventricular; Lipid Metabolism; Muscle Cells; Natriuretic Peptide, Brain; Oxidative Stress; Rats; Rats, Inbred SHR; Signal Transduction

Luteolin (LTL) serves essential roles in a wide variety of biological processes. Lipopolysaccharide (LPS) can lead to myocardial hypertrophy and autophagy. However, the roles of LTL on LPS‑induced cardiomyocyte hypertrophy and autophagy in rat cardiomyocytes have not yet been fully elucidated. In the present study, the morphology of cultured rat cardiomyocytes was observed under an inverted microscope. Cell viability was detected by MTT assay. α‑Actinin and microtubule‑associated protein 1 light chain 3 (LC3) expression levels were measured by immunofluorescence assay. In addition, the expression levels of atrial natriuretic peptide/brain natriuretic peptide (ANP/BNP), LC3, and autophagy‑ and Wnt signaling pathway‑associated genes were analyzed by reverse transcription‑quantitative polymerase chain reaction or western blot assays. The results indicated that LTL increased the cell viability of cardiomyocytes treated with LPS. LTL decreased the expression of cardiac hypertrophy associated markers (ANP and BNP). LTL decreased α‑actinin and LC3 expression levels in LPS‑treated cardiomyocytes. It was also demonstrated that LTL suppressed the mRNA and protein expression levels of LPS‑mediated autophagy and Wnt signaling pathway‑associated genes. In addition, it was demonstrated that silencing of β‑catenin inhibited LPS‑induced cardiomyocyte hypertrophy and the formation of autophagosomes. Thus, the present study suggested that LTL protected against LPS‑induced cardiomyocyte hypertrophy and autophagy in rat cardiomyocytes.

Topics: Animals; Atrial Natriuretic Factor; Autophagy; Disease Models, Animal; Gene Expression; Humans; Hypertrophy; Lipopolysaccharides; Luteolin; Microtubule-Associated Proteins; Myocytes, Cardiac; Natriuretic Peptide, Brain; Rats; RNA, Messenger; Signal Transduction

This paper was aimed to investigate the inhibitory effect of aconitine(AC) on angiotensin Ⅱ(Ang Ⅱ)-induced H9 c2 cell hypertrophy and explore its mechanism of action. The model of hypertrophy was induced by Ang Ⅱ(1×10-6 mol·L-1),and cardiomyocytes were incubated with different concentrations of AC. Western blot was used to quantify the protein expression levels of atrial natriuretic peptide(ANP),brain natriuretic peptide(BNP),β-myosin heavy chain(β-MHC),and α-smooth muscle actin(α-SMA). Real-time quantitative PCR(qRT-PCR) was used to quantify the mRNA expression levels of cardiac hypertrophic markers ANP,BNP and β-MHC. In addition,the fluorescence intensity of the F-actin marker,an important component of myofibrils,was detected by using laser confocal microscope. AC could significantly reverse the increase of total protein content in H9 c2 cells induced by Ang Ⅱ; qRT-PCR results showed that AC could significantly inhibit the ANP,BNP and β-MHC mRNA up-regulation induced by AngⅡ. Western blot results showed that AC could significantly inhibit the ANP,BNP and β-MHC protein up-regulation induced by AngⅡ. In addition,F-actin expression induced by Ang Ⅱ could be inhibited by AC,and multiple indicators of cardiomyocyte hypertrophy induced by Ang Ⅱ could be down-regulated,indicating that AC may inhibit cardiac hypertrophy by inhibiting the expression of hypertrophic factors,providing new clues for exploring the cardiovascular protection of AC.

Topics: Aconitine; Actins; Angiotensin II; Atrial Natriuretic Factor; Cardiac Myosins; Cardiomegaly; Cells, Cultured; Humans; Hypertrophy; Myocytes, Cardiac; Myosin Heavy Chains; Natriuretic Peptide, Brain

In response to assorted stimuli, the heart will develop into cardiomyocyte hypertrophy, but sustained cardiomyocyte hypertrophy will finally lead to heart failure. This research is aimed to examine the effect of VEGFB on cardiomyocyte hypertrophy by using the cardiomyocyte-derived cell line H9C2 of cultured rates. It turns out that VEGFB can positively prevent the Ang II-induced rising in the size of cardiomyocyte as well as reduce Ang II-induced mRNA and protein levels of β-MHC (β-myosin heavy chain), BNP (brain natriuretic peptide), and ANP (atrial natriuretic peptide). Moreover, VEGFB can regulate the decline of the Ang II-induced rising in Ca

Topics: Angiotensin II; Animals; Atrial Natriuretic Factor; Calcium; Cell Line; Cell Size; Cyclic GMP-Dependent Protein Kinase Type I; Gene Knockdown Techniques; Hypertrophy; Myocytes, Cardiac; Myosin Heavy Chains; Natriuretic Peptide, Brain; Rats; Signal Transduction; Vascular Endothelial Growth Factor B; Vascular Endothelial Growth Factor Receptor-1

Many clinical and experimental studies have shown that treatment with statins could prevent myocardial hypertrophy and remodeling induced by hypertension and myocardial infarction. But the molecular mechanism was not clear. We aimed to investigate the beneficial effects of atorvastatin on hypertension-induced myocardial hypertrophy and remodeling in spontaneously hypertensive rats (SHR) with the hope of revealing other potential mechanisms or target pathways to interpret the pleiotropic effects of atorvastatin on myocardial hypertrophy.. The male and age-matched animals were randomly divided into three groups: control group (8 WKY), SHR (8 rats) and intervention group (8 SHR). The SHR in intervention group were administered by oral gavage with atorvastatin (suspension in distilled water, 10 mg/Kg once a day) for 6 weeks, and the other two groups were administered by gavage with equal quantity distilled water. Blood pressure of rats was measured every weeks using a standard tail cuff sphygmomanometer. Left ventricular (LV) dimensions were measured from short-axis views of LV under M-mode tracings using Doppler echocardiograph. Cardiomyocyte apoptosis was assessed by the TUNEL assay. The protein expression of C/EBPβ, PGC-1α and UCP3 were detected by immunohistochemistry or Western blot analysis.. At the age of 16 weeks, the mean arterial pressure of rats in three groups were 103.6±6.1, 151.8±12.5 and 159.1±6.2 mmHg respectively, and there wasn't statistically significant difference between the SHR and intervention groups. Staining with Masson's trichrome demonstrated that the increased interstitial fibrosis of LV and ventricular remodeling in the SHR group were attenuated by atorvastatin treatment. Echocardiography examination exhibited that SHR with atorvastatin treatment showed an LV wall thickness that was obviously lower than that of water-treated SHR. In hypertrophic myocardium, accompanied by increasing C/EBPβ expression and the percentage of TUNEL-positive cells, the expression of Bcl-2/Bax ratio, PGC-1α and UCP3 were reduced, all of which could be abrogated by treatment with atorvastatin for 6 weeks.. This study further confirmed that atorvastatin could attenuate myocardial hypertrophy and remodeling in SHR by inhibiting apoptosis and reversing changes in mitochondrial metabolism. The C/EBPβ/PGC-1α/UCP3 signaling pathway might also be important for elucidating the beneficial pleiotropic effects of atorvastatin on myocardial hypertrophy.

Topics: Animals; Apoptosis; Atorvastatin; Atrial Natriuretic Factor; Blood Pressure; CCAAT-Enhancer-Binding Protein-beta; Echocardiography; Hypertension; Hypertrophy; Male; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Signal Transduction; Uncoupling Protein 3; Up-Regulation; Ventricular Remodeling

Myocardial fibrosis in hypertrophic cardiomyopathy (HCM) is associated with worse clinical outcomes. The availability of circulating biomarkers of myocardial fibrosis and hypertrophy would be helpful in clinical practice.. The aim of this study was to evaluate usefulness of various biomarkers of myocardial fibrosis and hypertrophy in HCM.. Levels of biomarkers: soluble ST2 (sST2), galectin-3 (Gal-3), growth differentiation factor-15 (GDF-15), NT-proBNP and high-sensitivity cardiac troponin T (hs-cTnT) were measured in 60 patients with HCM. All patients underwent cardiac magnetic resonance imaging to calculate parameters of hypertrophy and fibrosis.. We observed positive correlations among sST2 levels and left ventricular mass (LVM) (r = 0.32, p = 0.012), LV mass indexed for the body surface area (LVMI) (r = 0.27, p = 0.036) and maximal wall thickness (MWT) (r = 0.31, p = 0.015). No correlation was found between Gal-3 and GDF-15 levels and hypertrophy and fibrosis parameters. We observed positive correlations among hs-cTnT levels and LVM (r = 0.58, p < 0.0001), LVMI (r = 0.48, p = 0.0001), MWT (r = 0.31, p = 0.015) and late gadolinium enhancement (LGE) mass (r = 0.37, p = 0.003). There were positive correlations between NT-proBNP levels and LVM (r = 0.33, p = 0.01), LVMI (r = 0.41, p = 0.001), MWT (r = 0.42, p < 0.001) and LGE mass (r = 0.44, p < 0.001).. Although no correlation between sST2 levels and myocardial fibrosis was found, sST2 may provide some additional information about hypertrophy extension. NT-proBNP and hs-cTnT are useful biomarkers in assessment of hypertrophy and fibrosis in HCM.

Topics: Adult; Aged; Biomarkers; Cardiomyopathy, Hypertrophic; Fibrosis; Humans; Hypertrophy; Magnetic Resonance Imaging; Middle Aged; Natriuretic Peptide, Brain; Peptide Fragments; Troponin T

Loss of the nocturnal blood pressure (BP) drop is a risk factor for cardiovascular outcomes. However, clinical parameters that predispose to changes in nocturnal BP are currently uncertain. Given the possible involvement of salt sensitivity in nocturnal BP levels, we investigated a hypothesized association between plasma B-type natriuretic peptide (BNP) levels - a marker of body fluid retention - and nocturnal BP in a general population.. Study participants were 1020 general individuals. Participants were divided into four groups (riser, nondipper, dipper, and extreme dipper) by their percentage changes in nocturnal SBP measured using an ambulatory BP monitor.. Plasma BNP levels were positively associated with circadian BP change (β = 0.162, P < 0.001) independently of carotid hypertrophy (β = 0.133, P < 0.001), and awake heart rate (β = -0.102, P = 0.001) and SBP (β = -0.246, P < 0.001). Risers showed 1.6 times higher BNP levels than dippers, whereas oxygen desaturation during sleep was frequently observed in nondippers. Results of multinomial logistic regression analysis indicated that BNP level was a significant determinant for the riser pattern [odds ratio (OR) 1.27 (BNP 10 pg/ml), P < 0.001], whereas oxygen desaturation was specifically associated with the nondipping pattern (OR 1.04, P = 0.001). When participants were subdivided by BNP level, risers were more frequent in the high BNP subgroup (19.5%) than in the low BNP subgroup (6.7%) (OR 3.39, P < 0.001).. A slight increase in plasma BNP level was independently associated with rising nocturnal BP. Our results may help to understand the pathophysiology of circadian BP variation, and be a clue to identify individuals who require careful BP monitoring.

Topics: Aged; Blood Pressure; Blood Pressure Monitoring, Ambulatory; Carotid Arteries; Carotid Intima-Media Thickness; Circadian Rhythm; Female; Humans; Hypertrophy; Hypoxia; Male; Middle Aged; Natriuretic Peptide, Brain; Oxygen; Systole

Cardiomyocyte hypertrophy is an adaptive response of the heart to various types of stress. During the period of stress accumulation, the transition from physiological hypertrophy to pathological hypertrophy results in the promotion of heart failure. Gelsolin (GSN) is a member of the actin-binding proteins, which regulate dynamic actin filament organization by severing and capping. Moreover, GSN also regulates cell morphology, differentiation, movement, and apoptosis. In this study, we used H9c2 and H9c2-GSN stable clones in an attempt to understand the mechanisms of GSN overexpression in cardiomyocytes. These data showed that the overexpression of GSN in H9c2-induced cardiac hypertrophy and increased the pathological hypertrophy markers atrial natriuretic peptide brain natriuretic peptide. Furthermore, we found that E-cadherin expression decreased with the overexpression of GSN in H9c2, but β-catenin expression increased. These data presume that the cytoskeleton is loose. Further, previous studies show that the mitogen-activated protein kinase pathway can induce cardiac hypertrophy. Our data showed that p-p38 expression increased with the overexpression of GSN in H9c2, and the transcription factor p-GATA4 expression also increased, suggesting that the overexpression of GSN in H9c2-induced cardiac hypertrophy seemed to be regulated by the p38/GATA4 pathway. Moreover, we used both the p38 inhibitor (SB203580) and GSN siRNA to confirm our conjecture. We found that both of these factors significantly suppressed gelsolin-induced cardiac hypertrophy through p38/GATA4 signaling pathway. Therefore, we predict that the gene silencing of GSN and/or the downstream blocking of GSN along the p38 pathway could be applied to ameliorate pathological cardiac hypertrophy in the future.

Topics: Cardiomegaly; DNA-Binding Proteins; GATA4 Transcription Factor; Gelsolin; Gene Expression Regulation; Humans; Hypertrophy; Myocytes, Cardiac; Natriuretic Peptide, Brain; p38 Mitogen-Activated Protein Kinases; Promoter Regions, Genetic; Signal Transduction; Transcriptional Activation

We analyzed the outcome of nocturnal enuresis after adenotonsillectomy in children with sleep disordered breathing. We also evaluated differences in demographic, clinical, laboratory and polysomnography parameters between responders and nonresponders after adenotonsillectomy.. We prospectively evaluated children 5 to 18 years old diagnosed with sleep disordered breathing (snoring or obstructive sleep apnea syndrome) on polysomnography and monosymptomatic primary nocturnal enuresis requiring adenotonsillectomy to release upper airway obstruction. Plasma antidiuretic hormone and brain natriuretic peptide were measured preoperatively and 1 month postoperatively.. Sleep studies were done in 46 children and 32 also underwent blood testing preoperatively and postoperatively. Mean ± SD patient age was 8.79 ± 2.41 years and the mean number of wet nights weekly was 6.39 ± 1.26. Polysomnography revealed obstructive sleep apnea syndrome in 71.7% of patients and snoring in 28.3%. After adenotonsillectomy 43.5% of patients became dry. Preoperative polysomnography findings indicated that responders, who were dry, had significantly more arousals and obstructive apnea episodes but fewer awakenings than nonresponders, who were wet. Significant increases in plasma antidiuretic hormone and significant decreases in plasma brain natriuretic peptide were seen in all children with no difference between responders and nonresponders. No difference between the groups was noted in age, gender, race, body mass index, constipation, preoperative number of wet nights weekly or type of sleep disordered breathing.. Nocturnal enuresis resolved after adenotonsillectomy in almost half of the children with sleep disordered breathing. Those who became dry had more frequent arousal episodes caused by apnea events than those who remained wet.

Topics: Adolescent; Child; Child, Preschool; Comorbidity; Female; Humans; Hypertrophy; Male; Natriuretic Peptide, Brain; Nocturnal Enuresis; Palatine Tonsil; Polysomnography; Prospective Studies; Sleep Apnea, Obstructive; Snoring; Tonsillectomy; Vasopressins

The aim of the current study is to investigate the effect of visfatin on cardiomyocyte hypertrophy. Cultured H9c2 cardiomyocytes were exposed to visfatin at different concentrations for different periods of time, and the markers of cardiomyocyte hypertrophy were detected. Moreover, pravastatin, the inhibitor of endoplasmic reticulum stress (ERS) or thapsigargin, an ERS agonist was used respectively to pre-treat the cells before visfatin stimulation. F-actin staining was performed to measure the cell surface change. The mRNA expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and ERS markers including glucose-regulated protein 78(GRP78), C/EPB homologous protein (CHOP) and activating transcription factor 6 (ATF6) were assessed by real time RT-PCR. The change of protein level of GRP78 and CHOP was detected by Western blot. The experimental data demonstrated that exposure to 100 or 150 ng/mL concentrations of visfatin for 24 h, or 100 ng/mL of visfatin for 24 or 48 h, significantly increased the expression of markers for cardiomyocyte hypertrophy. Visfatin stimulation provoked ERS in H9c2 cells. Furthermore, pre-treatment with pravastatin partially inhibited the visfatin-induced mRNA expression of ANP and BNP in H9c2 cells, whereas thapsigargin promoted the visfatin-induced expression of cardiomyocyte hypertrophy markers. The results suggest that visfatin might induce cardiomyocyte hypertrophy via ERS -dependent pathways.

Topics: Actins; Activating Transcription Factor 6; Animals; Cell Line; Endoplasmic Reticulum Chaperone BiP; Heat-Shock Proteins; Hypertrophy; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nicotinamide Phosphoribosyltransferase; Rats; Transcription Factor CHOP

The precise molecular mechanisms leading to disturbance of Ca(2+)/calmodulin-dependent intracellular signalling in cardiac hypertrophy remains unclear. As an endogenous calmodulin regulator protein, the pathophysiology role of PEP-19 during cardiac hypertrophy was investigated in the present study. We here demonstrated that PEP-19 protein levels are significantly elevated in the aortic banding model in vivo and angiotensin II-induced cardiomyocyte hypertrophy in vitro. Consistent with inhibitory actions of PEP-19 on cardiomyocyte hypertrophy, induction of CaMKII and calcineurin activation as well as hypertrophy-related genes including atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was significantly inhibited by PEP-19 transfection. Moreover, PEP-19 partially ameliorates angiotensin II-induced elevation of phospho-phospholamban (Thr-17) and sarcoplasmic reticulum Ca(2+) release in cardiomyocytes. Together, our results suggest that PEP-19 attenuates angiotensin II-induced cardiomyocyte hypertrophy via suppressing the disturbance of CaMKII and calcineurin signaling.

Topics: Angiotensin II; Animals; Atrial Natriuretic Factor; Calcineurin; Calcium; Calcium Signaling; Calcium-Binding Proteins; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calmodulin; Calmodulin-Binding Proteins; Cardiomegaly; Cells, Cultured; Gene Expression; Hypertrophy; Male; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Rats, Sprague-Dawley; Sarcoplasmic Reticulum

MicroRNA-208a (miR208a) and mechanical stress play a key role in cardiac hypertrophy. The relationship between miR208a and mechanical stress in cultured cardiomyocytes has not been investigated. The molecular mechanisms underlying miR208a-induced hypertrophy of cardiomyocytes by mechanical stress is poorly understood. This study investigated whether miR208a is a critical regulator in cardiomyocyte hypertrophy under mechanical stretch.. Neonatal rat cardiomyocytes grown on a flexible membrane base were stretched at 60 cycles/minute. MiR real-time quantitative assays were used to quantify miRs. A quantitative sandwich enzyme immunoassay technique was used to measure transforming growth factor-β1 (TGF-β1). A (3)H-proline incorporation assay was used to measure protein synthesis.. Mechanical stretch significantly enhanced miR208a expression. Stretch significantly induced cardiomyocyte hypertrophic protein expression such as β-myosin heavy chain (MHCβ), thyroid hormone receptor-associated protein 100, myostatin, connexin 40, GATA4, and brain natriuretic peptide. MHCα was not induced by stretch. Overexpression of miR208a significantly increased MHCβ protein expression while pretreatment with antagomir208a significantly attenuated MHCβ protein expression induced by stretch and overexpression of miR208a. Mechanical stretch significantly increased the secretion of TGF-β1 from cultured cardiomyocytes. Exogenous addition of TGF-β1 recombinant protein significantly increased miR208a expression and pretreatment with TGF-β1 antibody attenuated miR208a expression induced by stretch. Mechanical stretch and overexpression of miR208a increased protein synthesis while antagomir208a attenuated protein synthesis induced by stretch and overexpression of miR208a.. Cyclic stretch enhances miR208a expression in cultured rat cardiomyocytes. MiR208a plays a role in stretch-induced cardiac hypertrophy. The stretch-induced miR208a is mediated by TGF-β1.

Topics: Animals; Cells, Cultured; Connexins; Gap Junction alpha-5 Protein; GATA4 Transcription Factor; Hypertrophy; Mediator Complex; MicroRNAs; Myocytes, Cardiac; Myosin Heavy Chains; Myostatin; Natriuretic Peptide, Brain; Protein Biosynthesis; Rats; Stress, Mechanical; Transforming Growth Factor beta1

The new adipocytokine visfatin is closely associated with the cardiovascular diseases, and expression of visfatin is elevated in the heart failure patients. However, at the cellular level, little work has been done on visfatin expression in the cardiomyocyte hypertrophy. Here, the authors investigated the expression and mechanisms of visfatin in angiotensin II (Ang II)-induced cardiomyocyte hypertrophy in vitro by means of the cultured neonatal rat cardiomyocytes.. After primary culture of 2- to 3-day-old Sprague-Dawley rat cardiomyocytes and cardiac fibroblasts, cardiomyocytes were pretreated with Ang II. Ang II type-1 receptor (AT1-R) antagonist telmisartan and Ang II type-2 receptor antagonist PD123319 were used to block effects of Ang II. These inhibitors used for the AT1-R pathway determination included SP600125, AG490 and U0126. Cell viability was examined using the 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The expression of visfatin was examined by means of reverse transcription-polymerase chain reaction and Western blot. The expression of brain natriuretic peptide was examined through western-blot analysis.. Visfatin was found expressed in cardiomyocytes as well as cardiac fibroblasts, and there was no significant difference at the mRNA and protein levels of visfatin. Ang II treatment induced the increased expression of visfatin and brain natriuretic peptide in a dose- and time-dependent manner in cardiomyocytes, and pretreatment with AT1-R antagonist telmisartan completely blocked Ang II-induced visfatin expression increasement. The increased visfatin expression was also blocked by the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway inhibitor AG490.. Visfatin expression was increased mainly through the AT1-R-JAK/STAT pathway in the process of Ang II-induced cardiomyocyte hypertrophy.

Topics: Angiotensin II; Animals; Hypertrophy; Janus Kinases; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nicotinamide Phosphoribosyltransferase; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Signal Transduction; STAT Transcription Factors

Cardiac disease is frequently reported in farmed animals, and stress has been implicated as a factor for myocardial dysfunction in commercial fish rearing. Cortisol is a major stress hormone in teleosts, and this hormone has adverse effects on the myocardium. Strains of rainbow trout (Oncorhynchus mykiss) selected for divergent post-stress cortisol levels [high responsive (HR) and low responsive (LR)] have been established as a comparative model to examine how fish with contrasting stress-coping styles differ in their physiological and behavioral profiles. We show that the mean cardiosomatic index (CSI) of adult HR fish was 34% higher than in LR fish, mainly because of hypertrophy of the compact myocardium. To characterize the hypertrophy as physiological or pathological, we investigated specific cardiac markers at the transcriptional level. HR hearts had higher mRNA levels of cortisol receptors (MR, GR1 and GR2), increased RCAN1 levels [suggesting enhanced pro-hypertrophic nuclear factor of activated T-cell (NFAT) signaling] and increased VEGF gene expression (reflecting increased angiogenesis). Elevated collagen (Col1a2) expression and deposition in HR hearts supported enhanced fibrosis, whereas the heart failure markers ANP and BNP were not upregulated in HR hearts. To confirm our results outside the selection model, we investigated the effect of acute confinement stress in wild-type European brown trout, Salmo trutta. A positive correlation between post-stress cortisol levels and CSI was observed, supporting an association between enhanced cortisol response and myocardial remodeling. In conclusion, post-stress cortisol production correlates with myocardial remodeling, and coincides with several indicators of heart pathology, well-known from mammalian cardiology.

Topics: Animals; Atrial Natriuretic Factor; Biomarkers; Collagen; Female; Fibrosis; Humans; Hydrocortisone; Hypertrophy; Myocardium; Natriuretic Peptide, Brain; NFATC Transcription Factors; Receptors, Glucocorticoid; Salmonidae; Stress, Physiological; Ventricular Remodeling

We examined which echocardiographic parameter correlated best with plasma brain natriuteric peptide (BNP) levels in treated hypertensive patients. Enrolled in the study were 122 treated hypertensive patients (70 ± 9 y). The left ventricular mass index and left atrial dimension (LAD) were measured using echocardiography as indexes of left ventricular hypertrophy and left atrial enlargement, respectively. Among all the echocardiographic parameters, LAD correlated best with BNP (r = 0.343, p < 0.001). Stepwise regression analysis showed that LAD (β coefficient = 0.513, p < 0.001) was independently associated with BNP. Left atrial enlargement, rather than left ventricular hypertrophy, may be clinically useful for predicting elevated BNP levels in treated hypertensive patients.

Topics: Adult; Aged; Aged, 80 and over; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Biomarkers; Cross-Sectional Studies; Female; Heart Atria; Humans; Hypertension; Hypertrophy; Hypertrophy, Left Ventricular; Male; Middle Aged; Natriuretic Peptide, Brain; Predictive Value of Tests; Regression Analysis; Retrospective Studies; Ultrasonography

Despite the availability of many pharmacological and mechanical therapies, the mortality rate among patients with congestive heart failure (CHF) remains high. We tested the hypothesis that TVP1022 (the S-isomer of rasagiline; Azilect), a neuroprotective and cytoprotective molecule, is also cardioprotective in the settings of experimental CHF in rats.. In rats with volume overload-induced CHF, we investigated the therapeutic efficacy of TVP1022 (7.5 mg/kg) on cardiac function, structure, biomarkers, and kidney function. Treatment with TVP1022 for 7 days before CHF induction prevented the increase in left ventricular end-diastolic area and end-systolic area, and the decrease in fractional shortening measured 14 days after CHF induction. Additionally, TVP1022 pretreatment attenuated CHF-induced cardiomyocyte hypertrophy, fibrosis, plasma and ventricular B-type natriuretic peptide levels, and reactive oxygen species expression. Further, in CHF rats, TVP1022 decreased cytochrome c and caspase 3 expression, thereby contributing to the cardioprotective efficacy of the drug. TVP1022 also enhanced the urinary Na(+) excretion and improved the glomerular filtration rate. Similar cardioprotective effects were obtained when TVP1022 was given to rats after CHF induction.. TVP1022 attenuated the adverse functional, structural, and molecular alterations in CHF, rendering this drug a promising candidate for improving cardiac and renal function in this disease state.

Topics: Animals; Cardiotonic Agents; Caspase 3; Cytochromes c; Disease Models, Animal; Fibrosis; Glomerular Filtration Rate; Heart Failure; Hypertrophy; Indans; Kidney; Myocytes, Cardiac; Natriuretic Peptide, Brain; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Ventricular Remodeling

The muscle-CAT (M-CAT) promoter element is found on promoters of most muscle-specific cardiac genes, but its role in cardiac pathology is poorly understood. Here we studied whether the M-CAT element is involved in hypertrophic process activated by mechanical stretch, and identified the intracellular pathways mediating the response. When an in vitro stretch model of cultured neonatal rat cardiomyocytes and luciferase reporter construct driven by rat B-type natriuretic peptide (BNP) promoter were used, mutation of M-CAT element inhibited not only the basal reporter activity (88%), but also the stretch-activated BNP transcription (58%, p < 0.001). Stretch-induced BNP promoter activation was associated with an increase in transcriptional enhancer factor-1 (TEF-1) binding activity after 24 h mechanical stretch (p < 0.05). Inhibition of mitogen-activated protein kinases ERK, JNK, or p38 attenuated stretch-induced BNP activation. Interestingly, as opposed to p38 and JNK, inhibition of ERK had no additional effect on transcriptional activity of BNP promoter harboring the M-CAT mutation, suggesting a pivotal role for ERK in regulating stretch-induced BNP transcription via M-CAT binding site. Finally, immunoprecipitation studies showed that mechanical stretch induced myocyte enhancer factor-2 (MEF-2) binding to TEF-1. These data suggest a central role for M-CAT element in regulation of mechanical stretch-induced hypertrophic response via ERK activation.

Topics: Animals; Basic-Leucine Zipper Transcription Factors; Cells, Cultured; DNA-Binding Proteins; Extracellular Signal-Regulated MAP Kinases; Hypertrophy; MAP Kinase Kinase 4; MAP Kinase Signaling System; MEF2 Transcription Factors; Muscle Proteins; Mutation; Myocardium; Myocytes, Cardiac; Myogenic Regulatory Factors; Natriuretic Peptide, Brain; p38 Mitogen-Activated Protein Kinases; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Regulatory Elements, Transcriptional; Transcriptional Activation

Hydrogen sulphide (H(2)S) has been shown to play a crucial role in cardiovascular physiology and disease. However, there is no information about the possible role of H(2)S in cardiomyocyte hypertrophy (CH). Our results showed that pretreatment with NaHS, an H(2)S donor, significantly reduced [(3)H]-leucine incorporation, cell surface area, mRNA expression of brain natriuretic peptide (BNP), intracellular reactive oxygen species (ROS), miR-21 and increased atrial natriuretic peptide (ANP) and miR-133a expression in hypertrophic cardiomyocytes. Anti-miR133a inhibitor transfection partly reduced the anti-hypertrophic effect of NaHS. In conclusion, H(2)S is a direct inhibitor of CH; it acts by increasing miR-133a and inhibiting the increase in intracellular ROS.

Topics: Animals; Cardiomegaly; Cell Line; Hydrogen Sulfide; Hypertrophy; MicroRNAs; Myocytes, Cardiac; Natriuretic Peptide, Brain; Rats; Reactive Oxygen Species; RNA, Messenger; Sulfides; Up-Regulation

The mixed-lineage kinases (MLKs) act upstream of mitogen-activated protein kinases, but their role in cardiac biology and pathology is largely unknown.. We investigated the effect of a MLK1-3 inhibitor CEP-11004 on G protein-coupled receptor agonist-induced stress response in neonatal rat cardiac myocytes in culture.. CEP-11004 administration dose-dependently attenuated phenylephrine and endothelin-1 (ET-1)-induced c-Jun N-terminal kinase activation. MLK inhibition also reduced ET-1- and phenylephrine-induced phosphorylation of p38 mitogen-activated protein kinase. In contrast, phenylephrine-induced extracellular signal-regulated kinase phosphorylation was further up-regulated by CEP-11004. ET-1 increased activator protein-1 binding activity 3.5-fold and GATA-binding protein 4 (GATA-4) binding activity 1.8-fold, both of which were attenuated with CEP-11004 administration by 59% and 63% respectively. Phenylephrine induced activator protein-1 binding activity by 2.6-fold, which was decreased by 81% with CEP-11004 administration. Phenylephrine also induced a 3.7-fold increase in the transcriptional activity of B-type natriuretic peptide (BNP), which was attenuated by 41% with CEP-11004 administration. In agreement, MLK inhibition also reduced hypertrophic agonist-induced secretion of immunoreactive atrial natriuretic peptide and BNP.. These results showed that inhibition of the MLK1-3 signalling pathway was sufficient for suppressing the activity of key nuclear effectors (GATA-4 and activator protein-1 transcription factors) in cardiac hypertrophy, and attenuated the agonist-induced atrial natriuretic peptide secretion and activation of BNP gene transcription.

Topics: Animals; Animals, Newborn; Atrial Natriuretic Factor; Carbazoles; Cardiomegaly; Cell Nucleus; Endothelin-1; Genes, jun; Heart; Hypertrophy; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase Kinases; Mitogen-Activated Protein Kinase Kinase Kinase 11; Mitogen-Activated Protein Kinases; Myocytes, Cardiac; Natriuretic Peptide, Brain; p38 Mitogen-Activated Protein Kinases; Phenylephrine; Phosphorylation; Rats; Rats, Sprague-Dawley; Signal Transduction; Transcription Factor AP-1; Transcription Factors

Atrial and brain natriuretic peptides (ANP and BNP, respectively) exert antihypertrophic effects in the heart via their common receptor, guanylyl cyclase (GC)-A, which catalyzes the synthesis of cGMP, leading to activation of protein kinase (PK)G. Still, much of the network of molecular mediators via which ANP/BNP-GC-A signaling inhibit cardiac hypertrophy remains to be characterized.. We investigated the effect of ANP-GC-A signaling on transient receptor potential subfamily C (TRPC)6, a receptor-operated Ca(2+) channel known to positively regulate prohypertrophic calcineurin-nuclear factor of activated T cells (NFAT) signaling.. In cardiac myocytes, ANP induced phosphorylation of TRPC6 at threonine 69, the PKG phosphorylation site, and significantly inhibited agonist-evoked NFAT activation and Ca(2+) influx, whereas in HEK293 cells, it dramatically inhibited agonist-evoked TRPC6 channel activity. These inhibitory effects of ANP were abolished in the presence of specific PKG inhibitors or by substituting an alanine for threonine 69 in TRPC6. In model mice lacking GC-A, the calcineurin-NFAT pathway is constitutively activated, and BTP2, a selective TRPC channel blocker, significantly attenuated the cardiac hypertrophy otherwise seen. Conversely, overexpression of TRPC6 in mice lacking GC-A exacerbated cardiac hypertrophy. BTP2 also significantly inhibited angiotensin II-induced cardiac hypertrophy in mice.. Collectively, these findings suggest that TRPC6 is a critical target of antihypertrophic effects elicited via the cardiac ANP/BNP-GC-A pathway and suggest TRPC6 blockade could be an effective therapeutic strategy for preventing pathological cardiac remodeling.

Topics: Anilides; Animals; Atrial Natriuretic Factor; Calcium Channels; Cells, Cultured; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Humans; Hypertrophy; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; NFATC Transcription Factors; Patch-Clamp Techniques; Rats; Receptors, Atrial Natriuretic Factor; Signal Transduction; Thiadiazoles; TRPC Cation Channels; TRPC6 Cation Channel

B-type natriuretic peptide (BNP) decreases cardiac preload and hypertrophy. As such, synthetic BNP, nesiritide, was approved for the treatment of acutely decompensated heart failure. However, two problems limit its therapeutic potential. First, ensuing hypertension decreases urine output, and second, guanylyl cyclase-A (GC-A), the primary signaling receptor for BNP, is down-regulated in heart failure. Thus, alternative or chimeric natriuretic peptides maintaining the renal but lacking the vasorelaxation properties of BNP provide an alternative approach. Here, we examined the ability of single amino acid substitutions in the conserved 17-amino acid disulfide ring structure of human BNP to activate GC-A and guanylyl cyclase-B (GC-B), which is not reduced in heart failure. We hypothesized that substitution of highly conserved residues in BNP with highly conserved residues from a GC-B-specific peptide would yield BNP variants with increased and decreased potency for human GC-B and GC-A, respectively. Substitution of Leu for Arg13 (l-bnp) yielded a 5-fold more potent activator of GC-B and 7-fold less potent activator of GC-A compared with wild type. l-bnp also bound GC-A 4.5-fold less tightly than wild type. In contrast, substitution of Met for Ser21 (M-BNP) had no effect. A peptide containing both the Leu and Met substitutions behaved similarly to l-bnp. Meanwhile, wild-type and l-bnp bound the natriuretic peptide clearance receptor with similar affinities. These data indicate that Arg13 of BNP is a critical discriminator of binding to guanylyl cyclase-linked but not clearance natriuretic peptide receptors, supporting designer natriuretic peptides as an alternative to wild-type BNP for the treatment of heart failure.

Topics: Down-Regulation; Guanylate Cyclase; Heart Failure; Humans; Hypertension; Hypertrophy; Kidney; Natriuretic Peptide, Brain; Natriuretic Peptides; Peptides; Receptors, Atrial Natriuretic Factor; Receptors, Peptide

The blood pressure-lowering effect of the renin inhibitor aliskiren equals that of angiotensin-converting enzyme (ACE) inhibitors and angiotensin (Ang) II type 1 (AT1) receptor blockers. Whether aliskiren offers end-organ protection remains to be investigated. Here, we compared the cardiac effects of aliskiren, the AT1 receptor blocker irbesartan and the ACE inhibitor captopril in spontaneously hypertensive rats (SHR) at equi-hypotensive doses.. SHR were treated for 1-3 weeks with vehicle, aliskiren, captopril or irbesartan (100, 3 and 15 mg/kg per day, respectively) using an osmotic minipump, and compared to vehicle-treated Wistar-Kyoto (WKY) controls. All drugs lowered (but not normalized) mean arterial pressure in SHR equi-effectively, as monitored by radiotelemetry, without altering heart rate. All drugs also reduced the increased cardiomyocyte area in SHR, and tended to normalize the elevated brain natriuretic peptide plasma levels. In the Langendorff set-up, all drugs normalized the diminished endothelium-dependent vasodilator response to bradykinin in SHR. Moreover, aliskiren and irbesartan, but not captopril, decreased the enhanced coronary Ang II response in SHR. Aliskiren reduced plasma renin activity and the plasma and tissue angiotensin levels at 1 week of treatment; yet, after 3 weeks of aliskiren treatment only the cardiac angiotensin levels remained suppressed, whereas no tissue angiotensin reductions were seen with captopril or irbesartan.. For a given decrease in blood pressure, aliskiren improves coronary endothelial function and decreases cardiac hypertrophy in SHR to at least the same degree as ACE inhibition and AT1 receptor blockade. In addition, aliskiren diminishes the enhanced Ang II response in the coronary circulation of SHR and offers superior long-term cardiac angiotensin suppression.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensins; Animals; Biphenyl Compounds; Blood Pressure; Captopril; Disease Models, Animal; Dose-Response Relationship, Drug; Fumarates; Heart; Heart Ventricles; Hypertension; Hypertrophy; Irbesartan; Male; Natriuretic Peptide, Brain; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renin; Tetrazoles

Left atrial volume (LAV) has recently emerged as a useful biomarker for risk stratification and risk monitoring in patients with end stage renal disease. We investigated the relationship between cardiac natriuretic peptides (atrial natriuretic peptide [ANP] and brain natriuretic peptide [BNP]) and norepinephrine (NE) with LAV and LAV changes over time in 199 end stage renal disease patients. At baseline, LAV was directly related to BNP (r=0.60), ANP (r=0.59), and NE (r=0.28; P<0.001), and these relationships held true in multiple-regression models adjusting for potential confounders (P< or =0.003). In the longitudinal study (17+/-2 months), LAV increased from 9.8+/-4.6 to 10.9+/-5.4 mL/m(2.7) (+11%). In a multiple linear regression model, BNP (beta=0.28; P=0.003), ANP (beta=0.22; P=0.03), and NE (beta=0.27; P=0.003) predicted LAV changes. The area under the receiver operating characteristic curve for predicting LAV changes (>3 mL/m(2.7) per year) of a risk score on the basis of standard risk factors was 0.72. Plasma BNP (+12%; P=0.004), ANP (+8%; P=0.03), NE (+8%; P=0.05) and midwall fraction shortening (+8%; P=0.05) increased the area under the receiver operating characteristic curve to a significant extent, whereas LV mass did not (+5%; P=0.18). Predictive models, including BNP, ANP, and NE, maintained a satisfactory discriminatory power for LAV and LAV changes also when tested by a bootstrap resampling technique. BNP and ANP are strongly related to LAV in the end stage renal disease patients and predict LAV changes over time in these patients. Because an increased LAV underlies diastolic dysfunction and/or volume overload (ie, potentially modifiable risk factors), the measurement of the plasma concentration of these compounds might be useful for risk stratification and for guiding treatment in dialysis patients.

Topics: Adult; Aged; Atrial Natriuretic Factor; Biomarkers; Cardiovascular Diseases; Cohort Studies; Echocardiography; Female; Heart Atria; Humans; Hypertrophy; Kidney Failure, Chronic; Longitudinal Studies; Male; Middle Aged; Natriuretic Peptide, Brain; Norepinephrine; Predictive Value of Tests; Regression Analysis; Risk Factors; ROC Curve

Altered mechanical stress and strain in cardiac myocytes induce modifications in gene expression that affects cardiac remodeling and myocyte contractile function. To study the mechanisms of mechanotransduction in cardiomyocytes, probing alterations in mechanics and gene expression has been an effective strategy. However, previous studies are self-limited due to the general use of isolated neonatal rodent myocytes or intact animals. The main goal of this study was to develop a novel tissue culture chamber system for mouse myocardium that facilitates loading of cardiac tissue, while measuring tissue stress and deformation within a physiological environment. Intact mouse right ventricular papillary muscles were cultured in controlled conditions with superfusate at 95% O2/ 5% CO2, and 34 degrees C, such that cell to extracellular matrix adhesions as well as cell to cell adhesions were undisturbed and both passive and active mechanical properties were maintained without significant changes. The system was able to measure the induction of hypertrophic markers (BNP, ANP) in tissue after 2 hrs and 5 hrs of stretch. ANP induction was highly correlated with the diastolic load of the muscle but not with developed systolic load. Load induced ANP expression was blunted in muscles from muscle-LIM protein knockout mice, in which defective mechanotransduction pathways have been predicted.

Topics: Animals; Atrial Natriuretic Factor; Gene Expression Regulation; Hypertrophy; Male; Mice; Mice, Inbred C57BL; Myocardial Contraction; Natriuretic Peptide, Brain; Papillary Muscles; Reverse Transcriptase Polymerase Chain Reaction; Stress, Mechanical; Time Factors; Tissue Culture Techniques

Our understanding of the natriuretic peptide system continues to evolve rapidly. B-type natriuretic peptide (BNP), originally thought to be a simple volume-regulating hormone that is produced in response to cardiac stretch, has been shown to also play important roles in modulating bronchodilation, endothelial function, and cardiac remodeling. Recent data demonstrate that elevated levels of BNP in patients with heart failure do not represent a simple ratcheting up of normal production in response to increased stimulus. Instead, we now know that chronic stimulation of BNP synthesis induces a reversion to fetal gene expression, resulting in production of high molecular weight forms of BNP that are functionally deficient. Standard point-of-care BNP assays are immunoassays that will detect any molecule containing the target epitopes. Consequently, these assays cannot distinguish between defective, high molecular weight forms of BNP and normal, physiologically active BNP. In 2 separate evaluations, mass spectroscopy detected little, if any, normal BNP in patients with heart failure, despite the appearance of high circulating levels of immunoreactive BNP (iBNP) using commercial assays. Therefore, these commercial assays should be considered to be only an indication of myocardial stress. They do not measure physiologic BNP activity. This accounts for the "BNP paradox," namely, that administration of exogenous recombinant human BNP (rhBNP, nesiritide) has substantial clinical and hemodynamic impact in the presence of high levels of circulating iBNP using commercial assays. In addition to its short-term hemodynamic impact, rhBNP may have other important effects in this setting, and further investigation is warranted.

Topics: Atrial Natriuretic Factor; Creatinine; Fibrosis; Heart Failure; Humans; Hypertrophy; Immunoassay; Myocardium; Natriuretic Agents; Natriuretic Peptide, Brain; Renin-Angiotensin System

Chronic inhibition of nitric oxide (NO) synthesis is associated with hypertension, myocardial ischemia, oxidative stress and hypertrophy; expression of adrenomedullin (AM) and intermedin (IMD) and their receptor activity modifying proteins (RAMPs 1-3) is augmented in cardiomyocytes, indicating that the myocardial AM/ IMD system may be activated in response to pressure loading and ischemic insult. The aim was to examine effects on (i) parameters of cardiomyocyte hypertrophy and on (ii) expression of AM and IMD and their receptor components in NO-deficient cardiomyocytes of an intervention chosen specifically for ability to alleviate pressure loading and ischemic injury concurrently.. The NO synthesis inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 35 mg.kg(-1).day(-1)) was given to rats for 8 weeks, with/ without concurrent administration of beta-adrenoceptor antagonist, atenolol (25 mg.kg(-1).day(-1)) / calcium channel blocker, nifedipine (20mg.kg(-1).day(-1)).. In L-NAME treated rats, atenolol / nifedipine abolished increases in systolic blood pressure and plasma AM and IMD levels and in left ventricular cardiomyocytes: (i) normalized increased cell width and mRNA expression of hypertrophic (sk-alpha-actin) and cardio-endocrine (ANP, BNP, ET) genes; (ii) normalized augmented membrane protein oxidation; (iii) normalized mRNA expression of AM, IMD, RAMP1, RAMP2 and RAMP3.. normalization of blood pressure and membrane oxidant status together with prevention of hypertrophy and normalization of the augmented expression of AM, IMD and their receptor components in NO-deficient cardiomyocytes by atenolol / nifedipine supports involvement of both pressure loading and ischemic insult in stimulating cardiomyocyte hypertrophy and induction of these counter-regulatory peptides and their receptor components. Attenuation of augmented expression of IMD in this model cannot however be explained simply by prevention of cardiomyocyte hypertrophy.

Topics: Adrenomedullin; Animals; Atenolol; Atrial Natriuretic Factor; Blood Pressure; Endothelin-1; Gene Expression Regulation; Hypertrophy; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Myocytes, Cardiac; Natriuretic Peptide, Brain; Neuropeptides; NG-Nitroarginine Methyl Ester; Nifedipine; Nitric Oxide; Oxidative Stress; Peptides; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Receptor Activity-Modifying Proteins; Receptors, Cell Surface; Systole

T-type Ca2+ channels (TCCs) are involved in cardiac cell growth and proliferation in cultured cardiomyocytes. Underlying molecular mechanisms are not well understood. In this study, we investigated the role of TCCs in signal transduction in cardiac hypertrophy compared with L-type Ca2+ channels (LCCs). Cardiomyocytes dissociated from neonatal mouse ventricles were cultured until stabilization. Cell hypertrophy was induced by reapplication of 1% fatal bovine serum (FBS) following a period (24 h) of FBS depletion. Cell surface area increased from 862+/-73 microm2 to 2153+/-131 microm2 by FBS stimulation in control (250+/-1.8%). T-type Ca2+ current (I(CaT)) was inhibited dose-dependently by kurtoxin (KT) and efonidipine (ED) with IC50 0.07 microM and 3.2 microM, respectively in whole-cell voltage clamp. On the other hand, 1 microM KT which inhibits I(CaT) over 90% did not effect on L-type Ca2+ current (I(CaL)). 10 microM ED had the ability of I(CaL) blockade as well as that of I(CaT) blockade. 3 microM nisoldipine (ND) suppressed I(CaL) by over 80%. The increase in cell surface area following reapplication of FBS as observed in control (250+/-1.8%) was significantly reduced in the presence of 1 microM KT (216+/-1.2%) and virtually abolished in the presence of 10 microM ED (97+/-0.8%) and 3 microM ND (80+/-1.1%). Hypertrophy was associated with an increase in BNP mRNA of 316+/-3.6% in control and this increase was reduced as well in the presence of 1 microM KT (254+/-1.8%) and almost abolished in the presence of 10 microM ED (116+/-1.1%) and 3 muM ND (93+/-0.8%). Immunolabeling showed that translocation of nuclear factor of activated T cells (NFAT3) into the nucleus in response to FBS stimulation was markedly inhibited by either KT or ED as well as ND. Calcineurin phosphatase activity was upregulated 2.2-fold by FBS, but KT, ED and ND decreased this upregulation (1.7-fold, 0.8-fold, and 0.7-fold with KT, ED and ND respectively). These results suggest that blockade of Ca2+ entry into cardiomyocytes via TCCs may block pathophysiological signaling pathways leading to hypertrophy as well as via LCCs. The mechanism may be the inhibition of calcineurin-mediated NFAT3 activation resulting in prevention of its translocation into the nucleus.

Topics: Active Transport, Cell Nucleus; Animals; Calcineurin; Calcium Channel Blockers; Calcium Channels, L-Type; Calcium Channels, T-Type; Cattle; Cells, Cultured; Dihydropyridines; Hypertrophy; Mice; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; Neurotoxins; NFATC Transcription Factors; Nisoldipine; Nitrophenols; Organophosphorus Compounds; Patch-Clamp Techniques; Scorpion Venoms

In chronic heart failure, atrial and brain natriuretic peptide expression is increased and serves as a clinical marker of cardiac hypertrophy. Chromogranin A is also up-regulated during chronic heart failure and associated with disease severity and prognosis. Significant decrease of both natriuretic peptide and hypertrophy after left ventricular assist device (LVAD) treatment was reported. This study investigated whether chromogranin A and neural cell adhesion molecule (NCAM)/CD56 are associated with cardiac hypertrophy and regulated by LVAD.. Expression of atrial and brain natriuretic peptide, chromogranin A, and NCAM/CD56 were investigated by immunohistochemistry and morphometrically quantified in 33 paired myocardial samples before and after LVAD. In a different set of patients, chromogranin A was evaluated in the plasma. Cardiomyocyte colocalization of brain natriuretic peptide and chromogranin A was visualized by immunofluorescence doublestaining.. Natriuretic peptide and chromogranin A protein expression is significantly decreased after LVAD (p < 0.05). NCAM/CD56 expression remains unaltered by unloading. In contrast with natriuretic peptide, chromogranin A and NCAM/CD56 expression is not correlated with cardiomyocyte diameters. Although increased compared with controls, no significant differences for chromogranin A plasma levels were found before and after LVAD. Sarcoplasmic colocalization of chromogranin A and brain natriuretic peptide is considerably decreased after LVAD.. Neither chromogranin A nor CD56 is associated with cardiac hypertrophy. Chromogranin A is significantly decreased by ventricular support. Sarcoplasmic colocalization of brain natriuretic peptide and chromogranin A is diminished after unloading. However, owing to its low expression, the negative regulation of chromogranin A is not reflected by plasma levels and thus does not appear to be an appropriate biomarker of reverse cardiac remodeling after unloading.

Topics: Adolescent; Adult; CD56 Antigen; Child; Child, Preschool; Chromogranin A; Chronic Disease; Down-Regulation; Female; Heart Failure; Heart-Assist Devices; Humans; Hypertrophy; Male; Middle Aged; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; Neural Cell Adhesion Molecules; Sarcoplasmic Reticulum; Tissue Distribution; Ventricular Remodeling

Evidences suggest that lipopolysaccharide (LPS) participates in the inflammatory response in the cardiovascular system; however, it is unknown if LPS is sufficient to cause the cardiac hypertrophy. In the present study, we treated H9c2 myocardiac cells with LPS to explore whether LPS causes cardiac hypertrophy, and to identify the precise molecular and cellular mechanisms behind hypertrophic responses. Here we show that LPS challenge induces pathological hypertrophic responses such as the increase in cell size, the reorganization of actin filaments, and the upregulation of hypertrophy markers including atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in H9c2 cells. LPS treatment significantly promotes the activation of GATA-4 and the nuclear translocation of NFAT-3, which act as transcription factors mediating the development of cardiac hypertrophy. After administration of inhibitors including U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), CsA (calcineurin inhibitor), FK506 (calcineurin inhibitor), and QNZ (NFkappaB inhibitor), LPS-induced hypertrophic characteristic features, such as increases in cell size, actin fibers, and levels of ANP and BNP, and the nuclear localization of NFAT-3 are markedly inhibited only by calcineurin inhibitors, CsA and FK506. Collectively, these results suggest that LPS leads to myocardiac hypertrophy through calcineurin/NFAT-3 signaling pathway in H9c2 cells. Our findings further provide a link between the LPS-induced inflammatory response and the calcineurin/NFAT-3 signaling pathway that mediates the development of cardiac hypertrophy.

Topics: Actins; Animals; Atrial Natriuretic Factor; Biomarkers; Calcineurin; Cell Nucleus; Cell Size; Fluorescent Antibody Technique; GATA4 Transcription Factor; Gene Expression Regulation; Hypertrophy; Lipopolysaccharides; Models, Biological; Myocytes, Cardiac; Natriuretic Peptide, Brain; NFATC Transcription Factors; Rats; Signal Transduction; Up-Regulation

The role played by IGF-II in signal transduction through the IGF-II/mannose-6-phosphate receptor (IGF2R) in heart tissue has been poorly understood. In our previous studies, we detected an increased expression of IGF-II and IGF2R in cardiomyocytes that had undergone pathological hypertrophy. We hypothesized that after binding with IGF-II, IGF2R may trigger intracellular signaling cascades involved in the progression of pathologically cardiac hypertrophy. In this study, we used immunohistochemical analysis of the human cardiovascular tissue array to detect expression of IGF2R. In our study of H9c2 cardiomyoblast cell cultures, we used the rhodamine phalloidin staining to measure the cell hypertrophy and western blot to measure the expression of cardiac hypertrophy markers atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in cells treated with IGF-II. We found that a significant association between IGF2R overexpression and myocardial infarction. The treatment of H9c2 cardiomyoblast cells with IGF-II not only induced cell hypertrophy but also increased the protein level of ANP and BNP. Using Leu27IGF-II, an analog of IGF-II which interacts selectively with the IGF2R, to specifically activate IGF2R signaling cascades, we found that binding of Leu27IGF-II to IGF2R led to an increase in the phosphorylation of protein Kinase C (PKC)-alpha and calcium/calmodulin-dependent protein kinase II (CaMKII) in a Galphaq-dependent manner. By the inhibition of PKC-alpha/CaMKII activity, we found that IGF-II and Leu27IGF-II-induced cell hypertrophy and upregulation of ANP and BNP were significantly suppressed. Taken together, this study provides a new insight into the effects of the IGF2R and its downstream signaling in cardiac hypertrophy. The suppression of IGF2R signaling pathways may be a good strategy to prevent the progression of pathological hypertrophy.

Topics: Atrial Natriuretic Factor; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Cells, Cultured; GTP-Binding Protein alpha Subunits, Gq-G11; Humans; Hypertrophy; Immunohistochemistry; Insulin-Like Growth Factor II; Myocardial Infarction; Myocytes, Cardiac; Natriuretic Peptide, Brain; Protein Kinase C-alpha; Receptor, IGF Type 2; Signal Transduction

There is increasing evidence showing that inflammation is involved in heart failure. However, heart failure may differ greatly due to different aetiologies. The role of inflammation in hypertensive heart failure, particularly in the early stage of cardiac dysfunction, has not been studied completely. This study aims at finding out whether inflammation is involved in the early stage of heart dysfunction due to hypertension.. Ten spontaneously hypertensive rats (SHR) and ten age-matched Wistar rats were used. Cardiac morphology and function, as well as coronary flow reserve, were examined by echocardiography. mRNAs for cytokines and brain natriuretic peptide were determined by RT-PCR.. The results demonstrate cardiac hypertrophy with increased heart/body weight ratio in SHR. Echocardiographic examination has shown that SHR developed diastolic heart dysfunction as determined by tissue Doppler without decrease in systolic function. In heart biopsies, there were increased mRNA levels for interleukin-6 and brain natriuretic peptide whereas decreased mRNA for interleukin-2, beta adrenergic receptor, interferon and NFkb in SHR as compared to WKY group. Coronary flow remained unchanged in both groups.. SHR developed cardiac hypertrophy complicated with diastolic heart dysfunction with increased expression of brain natriuretic peptide, down-regulation of beta adrenergic receptors and simultaneous up-regulation of IL-6, which indicates active proinflammatory process as, at least partly, underlying mechanism during the early stage when cardiac hypertrophy associated with diastolic dysfunction occurs.

Topics: Animals; Cardiomegaly; Diastole; Disease Models, Animal; Echocardiography; Gene Expression Regulation; Heart Failure; Hypertension; Hypertrophy; Interleukin-6; Myocardium; Natriuretic Peptide, Brain; Rats; Rats, Wistar; Receptors, Adrenergic, beta

In the infarcted rat heart, the increase of NO occurs in the hypertrophied myocardium of non-infarcted areas and its antihypertrophic efficacy has been well established. As another endogenous regulator and the reliable index of heart pathology, B-type natriuretic peptide also exhibits the antihypertrophic properties in many tissues by elevating intracellular cGMP. Several studies indicate that natriuretic peptides family may exert some actions in part via a nitric oxide pathway following receptor-mediated stimulation of iNOS. Therefore, it raises our great interest to ask what role NO plays in the antihypertrophic actions of B-type natriuretic peptide in cardiomyocytes. Incubation of cardiomyocytes under mild hypoxia for 12 h caused a significant increase in cellular protein content, protein synthesis and cell surface sizes. This growth stimulation was suppressed by exogenous B-type natriuretic peptide in a concentration dependent manner. Furthermore, the generation of intracellular cGMP, the upregulation of iNOS mRNA expression, the increase of iNOS activity and subsequent nitrite generation in hypertrophic cardiomyocytes was also increased by B-type natriuretic peptide. AG, a selective iNOS inhibitor, inhibited the upregulation of iNOS expression and the increase of iNOS activity by the combination of B-type natriuretic peptide/mild hypoxia or by the combination of 8-bromo-cGMP/mild hypoxia. Rp-8-br-cGMP, cGMP dependent protein kinase inhibitor, attenuated the actions of B-type natriuretic peptide and 8-bromo-cGMP which increases intracellular cGMP independent of B-type natriuretic peptide. In conclusion, our present data suggest that B-type natriuretic peptide exerted the antihypertrophic effects in cardiomyocytes, which was partially attributed to induction of iNOS-derived NO by cGMP pathway.

Topics: Animals; Animals, Newborn; Cell Hypoxia; Cell Proliferation; Cells, Cultured; Culture Media; Cyclic GMP; Gene Expression Regulation, Enzymologic; Hypertrophy; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nitric Oxide; Nitric Oxide Synthase Type II; Nitrites; Rats; Rats, Sprague-Dawley; RNA, Messenger

Cardiac hypertrophy is a complex and nonhomogenous response to various stimuli. In this study, we used high-density oligonucleotide microarray to examine gene expression profiles during physiological hypertrophy, pathological hypertrophy, and heart failure in Dahl salt-sensitive rats. There were changes in 404/3,160 and 874/3,160 genes between physiological and pathological hypertrophy and the transition from hypertrophy to heart failure, respectively. There were increases in stress response genes (e.g., heat shock proteins) and inflammation-related genes (e.g., pancreatitis-associated protein and arachidonate 12-lipoxygenase) in pathological processes but not in physiological hypertrophy. Furthermore, atrial natriuretic factor and brain natriuretic protein showed distinctive changes that are very specific to different conditions. In addition, we used a resampling-based gene score-calculating method to define significantly altered gene clusters, based on Gene Ontology classification. It revealed significant alterations in genes involved in the apoptosis pathway during pathological hypertrophy, suggesting that the apoptosis pathway may play a role during the transition to heart failure. In addition, there were significant changes in glucose/insulin signaling, protein biosynthesis, and epidermal growth factor signaling during physiological hypertrophy but not during pathological hypertrophy.

Topics: Animals; Apoptosis; Atrial Natriuretic Factor; Blotting, Northern; Cardiomegaly; Echocardiography; Epidermal Growth Factor; Gene Expression Profiling; Gene Expression Regulation; Heart Failure; Hypertrophy; Inflammation; Insulin; Natriuretic Peptide, Brain; Oligonucleotide Array Sequence Analysis; Pancreatitis-Associated Proteins; Physical Conditioning, Animal; Rats; Rats, Inbred Dahl; RNA; Signal Transduction

The blockade of beta-adrenergic receptors reduces both mortality and morbidity in patients with chronic heart failure, but the cellular mechanism remains unclear. Celiprolol, a selective beta(1)-blocker, was reported to stimulate the expression of endothelial NO synthase (eNOS) in the heart, and NO levels have been demonstrated to be related to myocardial hypertrophy and heart failure. Thus, we aimed to clarify whether celiprolol attenuates both myocardial hypertrophy and heart failure via the NO-signal pathway.. In rat neonatal cardiac myocytes, celiprolol inhibited protein synthesis stimulated by either isoproterenol or phenylephrine, which was partially suppressed by N(G)-nitro-L-arginine methyl ester (L-NAME). Four weeks after transverse aortic constriction (TAC) in C57BL/6 male mice, the ratio of heart weight to body weight (mg/g) (8.70+/-0.42 in TAC, 6.61+/-0.44 with celiprolol 100 mg x kg(-1) x d(-1) PO, P<0.01) and the ratio of lung weight to body weight (mg/g) (10.27+/-1.08 in TAC, 7.11+/-0.70 with celiprolol 100 mg x kg(-1) x d(-1) PO, P<0.05) were lower and LV fractional shortening was higher in the celiprolol-treated groups than in the TAC group. All of these improvements were blunted by L-NAME. Celiprolol treatment significantly increased myocardial eNOS and activated phosphorylation of eNOS. Myocardial mRNA levels of natriuretic peptide precursor type B and protein inhibitor of NO synthase, which were increased in the TAC mice, were decreased in the celiprolol-treated mice.. These findings indicated that celiprolol attenuates cardiac myocyte hypertrophy both in vitro and in vivo and halts the process leading from hypertrophy to heart failure. These effects are mediated by a selective beta1-adrenergic receptor blockade and NO-dependent pathway.

Topics: Adrenergic beta-1 Receptor Antagonists; Adrenergic beta-Antagonists; Animals; Cardiomegaly; Celiprolol; Cells, Cultured; Disease Progression; Drug Evaluation, Preclinical; Enzyme Induction; Fibrosis; Gene Expression Regulation; Heart Failure; Hypertrophy; Isoproterenol; Male; Mice; Mice, Inbred C57BL; Myocardium; Myocytes, Cardiac; Natriuretic Peptide, Brain; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phenylephrine; Pressure; Rats; RNA, Messenger; Transcription, Genetic; Vasodilator Agents

Angiotensin II (Ang II) upregulates vascular endothelial growth factor (VEGF) and activates vascular inflammation. However, the decisive role of VEGF in Ang II-induced vascular inflammation and remodeling has not been addressed. Ang II infusion to wild-type mice increased local expression of VEGF and its receptors in cells of aortic wall and plasma VEGF, and caused aortic inflammation (monocyte infiltration) and remodeling (wall thickening and fibrosis). Hypoxia-inducible factor-1alpha colocalized with VEGF-positive cell types. Blockade of VEGF by the soluble VEGF receptor 1 (sFlt-1) gene transfer attenuated the Ang II-induced inflammation and remodeling. The sFlt-1 gene transfer also inhibited the increased expression of VEGF and inflammatory factors such as monocyte chemoattractant protein-1. In contrast, sFlt-1 gene transfer did not affect Ang II-induced arterial hypertension and cardiac hypertrophy. VEGF is an essential mediator in Ang II-induced vascular inflammation and structural changes through its proinflammatory actions.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Aorta; Cell Division; Chemokine CCL2; Coronary Vessels; DNA-Binding Proteins; Extracellular Matrix Proteins; Gene Expression Profiling; Genetic Therapy; Hypertrophy; Hypertrophy, Left Ventricular; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Imidazoles; Intercellular Adhesion Molecule-1; Interleukin-1; Interleukin-6; Macrophages; Male; Mice; Mice, Inbred C57BL; Myosin Heavy Chains; Natriuretic Peptide, Brain; Nonmuscle Myosin Type IIB; Nuclear Proteins; Olmesartan Medoxomil; Receptors, CCR2; Receptors, Chemokine; Recombinant Fusion Proteins; Renin-Angiotensin System; Reverse Transcriptase Polymerase Chain Reaction; Tetrazoles; Transcription Factors; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tunica Media; Vascular Cell Adhesion Molecule-1; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; Vasculitis; Ventricular Remodeling

Aldosterone is produced not only in the adrenal gland but also in the extra-adrenal tissues, including failing human heart. This study examined the production of dehydroepiandrosterone (DHEA) in human heart and elucidated the possible physiological significance. Method and Results- Using left ventricular tissues obtained at autopsy, reverse transcription-polymerase chain reaction followed by Southern blot analysis revealed the gene expressions of CYP17. By measuring plasma aldosterone and DHEA levels at the coronary sinuses and aortic roots during cardiac catheterization, we found that DHEA but not aldosterone was secreted from control subjects (P<0.0001 and P=0.74, respectively), whereas aldosterone but not DHEA was secreted from patients with heart failure (P=0.0017 and P=0.67, respectively). To examine the significance of DHEA, we measured myocyte cell sizes and the gene expression of B-type natriuretic peptide (BNP), using a neonatal rat cardiocyte culture system. We found that DHEA (10(-8) mol/L) significantly inhibited the increase in myocyte cell sizes and BNP mRNA levels upregulated by endothelin-1 (P=0.031 and P<0.0001, respectively).. CYP17 gene expression and production of DHEA were demonstrated in human control heart. Also, we found that cardiac production of DHEA was suppressed in failing heart. We postulated that DHEA and/or its metabolites exert a cardioprotective action through antihypertrophic effects.

Topics: Adult; Aged; Aldosterone; Animals; Blotting, Southern; Cardiac Catheterization; Cell Size; Cells, Cultured; Dehydroepiandrosterone; Endothelin-1; Female; Heart Failure; Heart Ventricles; Humans; Hypertrophy; Male; Middle Aged; Myocytes, Cardiac; Natriuretic Peptide, Brain; Neoplasms; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Steroid 11-beta-Hydroxylase; Steroid 17-alpha-Hydroxylase

In overloaded heart the cardiomyocytes adapt to increased mechanical and neurohumoral stress by activation of hypertrophic program, resulting in morphological changes of individual cells and specific changes in gene expression. Accumulating evidence suggests an important role for the zinc finger transcription factor GATA-4 in hypertrophic agonist-induced cardiac hypertrophy. However, its role in stretch-induced cardiomyocyte hypertrophy is not known. We employed an in vitro mechanical stretch model of cultured cardiomyocytes and used rat B-type natriuretic peptide promoter as stretch-sensitive reporter gene. Stretch transiently increased GATA-4 DNA binding activity and transcript levels, which was followed by increases in the expression of B-type natriuretic peptide as well as atrial natriuretic peptide and skeletal alpha-actin genes. The stretch inducibility mapped primarily to the proximal 520 bp of the B-type natriuretic peptide promoter. Mutational studies showed that the tandem GATA consensus sites of the proximal promoter in combination with an Nkx-2.5 binding element are critical for stretch-activated B-type natriuretic peptide transcription. Inhibition of GATA-4 protein production by adenovirus-mediated transfer of GATA-4 antisense cDNA blocked stretch-induced increases in B-type natriuretic peptide transcript levels and the sarcomere reorganization. The proportion of myocytes with assembled sarcomeres in control adenovirus-infected cultures increased from 14 to 59% in response to stretch, whereas the values for GATA-4 antisense-treated cells were 6 and 13%, respectively. These results show that activation of GATA-4, in cooperation with a factor binding on Nkx-2.5 binding element, is essential for mechanical stretch-induced cardiomyocyte hypertrophy.

Topics: Animals; Atrial Natriuretic Factor; DNA-Binding Proteins; GATA4 Transcription Factor; Hypertrophy; Mechanotransduction, Cellular; Myocytes, Cardiac; Natriuretic Peptide, Brain; Nuclear Proteins; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transcription Factor AP-1; Transcription Factors; Transcriptional Activation

The peroxisome proliferator activated receptors (PPARs) appear to have beneficial effects in the cardiovascular system. PPAR gamma has been shown previously to exert an inhibitory effect on cardiac myocyte hypertrophy in vivo and in vitro. Using endothelin to activate the hypertrophic program in neonatal rat cardiac myocytes, we demonstrate that PPAR alpha ligands (fenofibrate and WY14,643) suppress hypertrophy-dependent increases in protein synthesis, cell surface area, and sarcomeric organization in vitro. This was accompanied by a decrease in brain natriuretic peptide gene expression, a marker of transcriptional activation in hypertrophy. These effects were equivalent to or greater than those seen with the PPAR gamma agonist rosiglitazone. Fenofibrate and rosiglitazone suppressed endothelin stimulation of human brain natriuretic peptide gene promoter activity, and this effect was amplified by cotransfection of PPAR alpha and PPAR gamma expression vectors, respectively. The fenofibrate-dependent suppression of endothelin's stimulatory activity was dependent upon promoter sequence positioned between -904 and -40 relative to the transcription start site and did not appear to involve a number of positive and negative regulatory elements that are known to govern transcription of this gene. These findings suggest that PPAR alpha ligands could prove to be useful in the management of disorders associated with hypertrophy and remodeling of the myocardium.

Topics: Animals; Animals, Newborn; Base Sequence; Cell Size; Cells, Cultured; Fenofibrate; Gene Expression; Heart Ventricles; Hypertrophy; Hypoglycemic Agents; Hypolipidemic Agents; Ligands; Molecular Sequence Data; Mutagenesis, Site-Directed; Myocytes, Cardiac; Natriuretic Peptide, Brain; Peroxisome Proliferators; Pyrimidines; Rats; Receptors, Cytoplasmic and Nuclear; Rosiglitazone; Sarcomeres; Thiazoles; Thiazolidinediones; Transcription Factors

In cardiac hypertrophy, both excessive enlargement of cardiac myocytes and progressive interstitial fibrosis are well known to occur simultaneously. In the present study, to investigate the interaction between ventricular myocytes (MCs) and cardiac nonmyocytes (NMCs), mostly fibroblasts, during cardiocytes hypertrophy, we examined the change in cell size and gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in cultured MCs as markers for hypertrophy in the neonatal rat ventricular cardiac cell culture system.. The size of cultured MCs significantly increased in the MC-NMC coculture. Concomitantly, secretions of ANP and BNP into culture media were significantly increased in the MC-NMC coculture compared with in the MC culture (with the possible contamination of NMC <1% of MC). Moreover, in the MC culture, enlargement of MC and an increase in ANP and BNP secretions were induced by treatment with conditioned media of the NMC culture. A considerable amount of endothelin (ET)-1 production was detected in the NMC-conditioned media. BQ-123, an ET-A receptor antagonist, and bosentan, a nonselective ET receptor antagonist, significantly blocked the hypertrophic response of MCs induced by treatment with NMC-conditioned media. Angiotensin II (Ang II) (10(-10) to 10(-6) mol/L) and transforming growth factor-beta1 (TGF-beta1) (10(-13) to 10(-9) mol/L), both of which are known to be cardiac hypertrophic factors, did not induce hypertrophy in MC culture, but both Ang II and TGF-beta1 increased the size of MCs and augmented ANP and BNP productions in the MC-NMC coculture. This hypertrophic activity of Ang II and TGF-beta1 was associated with the potentiation of ET-1 production in the MC-NMC coculture, and the effect of Ang II or TGF-beta1 on the secretions of ANP and BNP in the coculture was significantly suppressed by pretreatment with BQ-123.. These results demonstrate that NMCs regulate MC hypertrophy at least partially via ET-1 secretion and that the interaction between MCs and NMCs plays a critical role during the process of Ang II- or TGF-beta1-induced cardiocyte hypertrophy.

Topics: Angiotensin II; Animals; Atrial Natriuretic Factor; Cardiomegaly; Cattle; Coculture Techniques; Culture Media, Conditioned; Endothelin Receptor Antagonists; Endothelin-1; Hypertrophy; Lipoproteins, LDL; Myocardium; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Paracrine Communication; Rats; Rats, Wistar; Receptors, Angiotensin; Receptors, Endothelin; RNA, Messenger; Transforming Growth Factor beta; Ventricular Function

Plasma concentrations of immunoreactive (ir) atrial (ANP) and brain (BNP) natriuretic peptides were measured in the prehypertensive and hypertensive phases in spontaneously hypertensive rats (SHR) and in the malignant phase of hypertension caused by deoxycorticosterone acetate (DOCA)-salt in SHR. The secretory rate of ANP and BNP were examined in the perfusion of isolated beating heart before and after atrial removal. Plasma irANP and irBNP in mature SHR were higher than those of control Wistar-Kyoto (WKY) rats, whereas ANP and BNP values in young SHR did not differ from those of control WKY rats. DOCA-salt treatment for 8 weeks markedly increased blood pressure, ventricular weight, and plasma irANP and irBNP in SHR. ANP and BNP values were positively correlated with ventricular weight in DOCA-salt SHR. The secretory rate of ANP and BNP from the perfused whole heart were much higher in DOCA-salt SHR than other rat groups. A large amount of BNP was secreted from the hypertrophied ventricles in DOCA-salt SHR. In contrast, ANP was mainly secreted from the atrium in all rat groups. High-performance liquid chromatography profiles of extract in plasma showed that a major component of irANP and irBNP corresponded to synthetic rat ANP-(1-28) and rat BNP-45, respectively. Results suggest that both rat ANP-(1-28) and rat BNP-45 are markedly increased in plasma in DOCA-salt-induced malignant hypertension of SHR and that the major source of circulating BNP is the hypertrophied ventricles in this model.

Topics: Aging; Animals; Atrial Natriuretic Factor; Cerebral Ventricles; Chromatography, High Pressure Liquid; Desoxycorticosterone; Hypertension, Malignant; Hypertrophy; In Vitro Techniques; Myocardium; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Osmolar Concentration; Radioimmunoassay; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Sodium Chloride