Natriuretic Peptide Gene Expression Research Articles

Human Engineered Cardiac Tissues Created Using Induced Pluripotent Stem Cells Reveal Functional Characteristics of BRAF-Mediated Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death that often goes undetected in the general population. HCM is also prevalent in patients with cardio-facio-cutaneous syndrome (CFCS), which is a genetic disorder characterized by aberrant signaling in the RAS/MAPK signaling cascade. Understanding the mechanisms of HCM development in such RASopathies may lead to novel therapeutic strategies, but relevant experimental models of the human condition are lacking. Therefore, the objective of this study was to develop the first 3D human engineered cardiac tissue (hECT) model of HCM. The hECTs were created using human cardiomyocytes obtained by directed differentiation of induced pluripotent stem cells derived from a patient with CFCS due to an activating BRAF mutation. The mutant myocytes were directly conjugated at a 3:1 ratio with a stromal cell population to create a tissue of defined composition. Compared to healthy patient control hECTs, BRAF-hECTs displayed a hypertrophic phenotype by culture day 6, with significantly increased tissue size, twitch force, and atrial natriuretic peptide (ANP) gene expression. Twitch characteristics reflected increased contraction and relaxation rates and shorter twitch duration in BRAF-hECTs, which also had a significantly higher maximum capture rate and lower excitation threshold during electrical pacing, consistent with a more arrhythmogenic substrate. By culture day 11, twitch force was no longer different between BRAF and wild-type hECTs, revealing a temporal aspect of disease modeling with tissue engineering. Principal component analysis identified diastolic force as a key factor that changed from day 6 to day 11, supported by a higher passive stiffness in day 11 BRAF-hECTs. In summary, human engineered cardiac tissues created from BRAF mutant cells recapitulated, for the first time, key aspects of the HCM phenotype, offering a new in vitro model for studying intrinsic mechanisms and screening new therapeutic approaches for this lethal form of heart disease.

Endoplasmic Reticulum Stress is Involved in DFMO Attenuating Isoproterenol-Induced Cardiac Hypertrophy in Rats

Background/Aims: Studies performed in experimental animals have shown that polyamines contribute to several physiological and pathological processes, including cardiac hypertrophy. This involves an increase in ornithine decarboxylase (ODC) activity and intracellular polyamines associated with regulation of gene expression. Difluoromethylornithine (DFMO), an irreversible inhibitor of ODC, has attracted considerable interest for its antiproliferative role, which it exerts through inhibition of the polyamine pathway and cell turnover. Whether DFMO attenuates cardiac hypertrophy through endoplasmic reticulum stress (ERS) is unclear. Methods: Myocardial hypertrophy was simulated by isoproterenol (ISO). Polyamine depletion was achieved using DFMO. Hypertrophy was estimated using the heart/body index and atrial natriuretic peptide (ANP) gene expression. Cardiac fibrosis and apoptosis were measured by Masson and TUNEL staining. Expression of ODC and spermidine/spermine N1-acetyltransferase (SSAT) were analyzed via real-time PCR and Western blot analysis. Protein expression of ERS and apoptosis factors were analyzed using Western blot analysis. Results: DFMO treatments significantly attenuated hypertrophy and apoptosis induced by ISO in cardiomyocytes. DFMO down-regulated the expression of ODC, glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), cleaved caspase-12, and Bax and up-regulated the expression of SSAT and Bcl-2. Finally, these changes were partially reversed by the addition of exogenous putrescine. Conclusion: The data presented here suggest that polyamine depletion could inhibit cardiac hypertrophy and apoptosis, which is closely related to the ERS pathway.

Inhibition of Cardiomyocytes Hypertrophy by Resveratrol Is Associated with Amelioration of Endoplasmic Reticulum Stress

Background/Aims: Resveratrol (Res), a polyphenol antioxidant found in red wine, has been shown to play a cardioprotective role. This study was undertaken to investigate whether Res can protect the heart suffering from hypertrophy injuries induced by isoproterenol (ISO), and whether the protective effect is mediated by endoplasmic reticulum (ER) stress. Methods: Cardiomyocytes were randomly assigned to the control group, ISO group (100 nM ISO for 48 h), Res + ISO group (50 μM Res and 100 nM ISO for 48 h) and Res group (50 μM Res for 48h only). Hypertrophy was estimated by measuring the cell surface area and the atrial natriuretic peptide (ANP) gene expression. Apoptosis was measured using Hoechst 33258 staining and transmission electron microscopy. Protein expression of ER stress and apoptosis factors was analyzed using Western Blot analysis. Results: Res effectively suppress the cardiomyocytes hypertrophy and apoptosis induced by ISO, characterized by the reduction of the myocardial cell surface area, the ANP gene expression, the LDH and MDA leakage amount and the rate of cell apoptosis, while decrease of the protein expression of GRP78, GRP94 and CHOP, and reverse the expression of Bcl-2 and Bax. Conclusion: In summary, Res treatment effectively suppressed myocardial hypertrophy and apoptosis at least partially via inhibiting ER stress.

Abstract 6: Vitamin D3 Repletion Improves Heart Failure Patient Quality of Life and Neurohormonal Indices

Background: Vitamin D deficiency has been associated with cardiovascular mortality and sudden cardiac death in heart failure patients. Vitamin D may influence parathyroid hormone, the renin-angiotensin axis, natriuretic peptide gene expression, cardiac contractility, and cardiopulmonary function. Heart Failure (HF) studies using vitamin D to date have typically not used adequate repletion doses. Objectives: The primary objectives of this research were to determine if vitamin D repletion over a six month period in New York Heart Association (NYHA) Class II-III HF patients would result in a change in neurohormonal markers, cardiopulmonary exercise parameters, circulating 25- hydroxyvitamin D, and quality of life. Methods: A randomized, double-blinded, placebo-controlled trial assessing adjunctive Vitamin D3 supplementation in the treatment of NYHA Class II-III HF patients was conducted. Patients received 10,000 International Units (IU) per day of vitamin D3 or placebo for 6 months. Inclusion Criteria: 1) 25-hydroxyvitamin D level ≤32 ng/ml 2) stable medical regimen for 3 months. Exclusion Criteria: 1) any clinically unstable medical disorder 2) supplementation of vitamin D3 or D2 of greater than or equal to 2,000 IU/day. Study endpoints were: 1) B-type Natriuretic Peptide (BNP), 2) cardiopulmonary exercise parameters using Shape HF, 3) 25-hydroxyvitamin D, 4) intact parathyroid hormone (PTH), and 5) quality of life with the Kansas City Cardiomyopathy Questionnaire (KCCQ). Statistical analysis included independent samples t-test and multivariate regression. Results: A total of 34 patients completed the study. When adjusted for baseline 25-hydroxyvitamin D, the difference between groups for BNP was significant ([[Unable to Display Character: ∆]]540 ±1928 pg/ml placebo vs [[Unable to Display Character: ∆]] 35 pg/ml ±1054 pg/ml treatment p=0.009). 25-hydroxyvitamin D was [[Unable to Display Character: ∆]]48.9 ±32 ng/ml treatment vs [[Unable to Display Character: ∆]]3.6 ± 9.4 ng/ml placebo, p<0.001 (mean 68 ng/ml treatment vs 23 ng/ml placebo). No toxicity was observed with treatment. PTH and exercise chronotropic response index trended towards improvement in the treatment group vs placebo group, respectively (([[Unable to Display Character: ∆]]-20 ±20 pg/ml vs [[Unable to Display Character: ∆]]7 ±54pg/ml (p=0.06)) and ([[Unable to Display Character: ∆]]0.13±0.26 versus [[Unable to Display Character: ∆]]-0.03 ± 0.23, p=0.12)). KCCQ quality of life total symptom ([[Unable to Display Character: ∆]]16 ±16 treatment vs [[Unable to Display Character: ∆]]-12 ±15 placebo, p< 0.001) and individual scores significantly improved from baseline in the treatment group. Conclusions: Preliminary results show that vitamin D3 treatment of 10,000 IU/day in heart failure patients is safe, results in adequate circulating 25-hydroxyvitamin D levels, and achieves improvement in surrogate endpoint markers of HF outcomes.

Different effects of phase advance and delay in rotating light-dark regimens on clock and natriuretic peptide gene expression in the rat heart.

Under physiological conditions the mammalian circadian system is synchronized to a cyclic environment. The central oscillator in the suprachiasmatic nuclei (SCN) responds predominantly to an external light (L) dark (D) cycle. Peripheral oscillators are more efficiently synchronized by metabolic cues. When the circadian system is exposed to opposing synchronizing cues, peripheral oscillators uncouple from the SCN. To consider influence of phase advances and delays in light regimens mimicking shift work, we analyzed the expression of clock genes (per2, bmal1) and natriuretic peptides (anp, bnp) in the heart of male rats. Experimental groups were exposed to a rotating LD regimen with either 8 h phase advance or delay for 11 weeks. Samples were taken for a 24 h cycle in 4 h intervals. Peripheral oscillators responded to rotating phase advance by decreasing rhythm robustness, while phase delay mostly influenced the phase angle between the acrophase of rhythmic gene expression and the external LD cycle. The expression of anp was arrhythmic in the heart of control rats and was not influenced by rotating LD regimens. The expression of bnp showed a daily rhythm with a nadir during the active phase. The daily rhythm in bnp expression diminished under rotating LD regimen conditions.

Therapeutic silencing of miR-652 restores heart function and attenuates adverse remodeling in a setting of established pathological hypertrophy.

Expression of microRNA-652 (miR-652) increases in the diseased heart, decreases in a setting of cardioprotection, and is inversely correlated with heart function. The aim of this study was to assess the therapeutic potential of inhibiting miR-652 in a mouse model with established pathological hypertrophy and cardiac dysfunction due to pressure overload. Mice were subjected to a sham operation or transverse aortic constriction (TAC) for 4 wk to induce hypertrophy and cardiac dysfunction, followed by administration of a locked nucleic acid (LNA)-antimiR-652 (miR-652 inhibitor) or LNA control. Cardiac function was assessed before and 8 wk post-treatment. Expression of miR-652 increased in hearts subjected to TAC compared to sham surgery (2.9-fold), and this was suppressed by ∼95% in LNA-antimiR-652-treated TAC mice. Inhibition of miR-652 improved cardiac function in TAC mice (fractional shortening:29±1% at 4 wk post-TAC compared to 35±1% post-treatment) and attenuated cardiac hypertrophy. Improvement in heart function was associated with reduced cardiac fibrosis, less apoptosis and B-type natriuretic peptide gene expression, and preserved angiogenesis. Mechanistically, we identified Jagged1 (a Notch1 ligand) as a novel direct target of miR-652. In summary, these studies provide the first evidence that silencing of miR-652 protects the heart against pathological remodeling and improves heart function.

Abstract 50: Therapeutic Silencing of miRNA-652 Restores Cardiac Function and Attenuates Pathological Remodeling in a Mouse Model of Pressure Overload

Introduction: Targeting microRNAs differentially regulated in settings of stress and protection could represent a new approach for the treatment of heart failure. miR-652 expression increased in hearts of a cardiac stress mouse model and was downregulated in a model of cardiac protection. Aim: To assess the therapeutic potential of silencing miR-652 in a mouse model with established pathological hypertrophy and cardiac dysfunction due to pressure overload. Methods: Mice were subjected to a sham operation (n=10) or transverse aortic constriction (TAC, n=14) for 4 weeks to induce hypertrophy and cardiac dysfunction. Mice were subcutaneously administered a locked nucleic acid (LNA)-antimiR-652 or LNA-control. Cardiac function was assessed by echocardiography before and 8 weeks post treatment, followed by molecular and histological analyses. Results: Expression of miR-652 increased in hearts subjected to pressure overload compared to sham operated mice (2.9 fold, n=3-5, P<0.05), but was silenced in hearts of mice administered LNA-antimiR-652 (95% decrease, n=3-7, P<0.05). In mice subjected to pressure overload, inhibition of miR-652 improved cardiac function (29±1% at 4 weeks post TAC compared to 35±1% post treatment, n=7, P<0.001) and attenuated cardiac hypertrophy. Functional and morphologic improvements in hearts of treated mice were associated with reduced cardiac fibrosis, apoptosis, cardiomyocyte size; decreased B-type natriuretic peptide gene expression; and preserved angiogenesis (all P<0.05, n=4-7/group). Mechanistically, we identified Jagged1, a Notch1 ligand, as a direct target of miR-652 by luciferase assay. Jagged1 and Notch1 mRNA were upregulated in hearts of TAC treated mice (1.2-1.7 fold, n=7, P<0.05). Importantly, chronic knockdown of miR-652 was not associated with any notable toxicity in other tissues. Conclusion: Therapeutic silencing of miR-652 protects the heart against pathological cardiac remodeling and improves heart function via mechanisms that are associated with preserved angiogenesis, decreased fibrosis and upregulation of a miR-652 target, Jagged1. These studies provide the first evidence that targeted inhibition of miR-652 could represent an attractive approach for the treatment of heart failure.

Association between the atrial natriuretic peptide rs5065 gene polymorphism and the presence and severity of coronary artery disease in an Iranian population

The atrial natriuretic peptide (ANP) gene expression and some of its related single-nucleotide polymorphisms have been well established as a characterized biomarker of cardiovascular diseases. In the present study, we aimed to evaluate the potential association between one of the introduced ANP gene polymorphisms of 2238 T/C (rs5065) with coronary artery disease (CAD) in an Iranian population. A total of 573 patients with CAD according to angiography reports and 293 controls without any evidence of CAD were enrolled. Allelic discrimination of the single-nucleotide polymorphism rs5065 in both groups was performed using a High Resolution Melt technique in real-time PCR analysis. With respect to the prevalence of different genotypes of rs5065 polymorphism, the frequency of the T allele in the CAD group was significantly lower in CAD than that in the non-CAD group (59.7 vs. 65.1%, P=0.032). A significant inverse association was also found between the frequency of T allele and severity of CAD assessed by the Gensini score; the average of this score in T-allele carriers was 38.6±41.6 and that in C-allele carriers was 57.7±46.3 (P≤0.0001). Using multivariable linear regression modeling with the presence of baseline variables, the presence of the rs5065 ANP T allele could predict decreased severity of CAD assessed by the Gensini score in our population. The presence of the rs5065 ANP polymorphism is potentially associated with a reduced risk of CAD as well as with reduced severity of CAD independent of the general risk factors of CAD.

Differential gene expression of C-type natriuretic peptide and its related molecules in dilated and ischemic cardiomyopathy. A new option for the management of heart failure

Differential gene expression of C-type natriuretic peptide and its related molecules in dilated and ischemic cardiomyopathy. A new option for the management of heart failure

Probiotic Administration Attenuates Myocardial Hypertrophy and Heart Failure After Myocardial Infarction in the Rat

Probiotics are extensively used to promote gastrointestinal health, and emerging evidence suggests that their beneficial properties can extend beyond the local environment of the gut. Here, we determined whether oral probiotic administration can alter the progression of postinfarction heart failure. Rats were subjected to 6 weeks of sustained coronary artery occlusion and administered the probiotic Lactobacillus rhamnosus GR-1 or placebo in the drinking water ad libitum. Culture and 16s rRNA sequencing showed no evidence of GR-1 colonization or a significant shift in the composition of the cecal microbiome. However, animals administered GR-1 exhibited a significant attenuation of left ventricular hypertrophy based on tissue weight assessment and gene expression of atrial natriuretic peptide. Moreover, these animals demonstrated improved hemodynamic parameters reflecting both improved systolic and diastolic left ventricular function. Serial echocardiography revealed significantly improved left ventricular parameters throughout the 6-week follow-up period including a marked preservation of left ventricular ejection fraction and fractional shortening. Beneficial effects of GR-1 were still evident in those animals in which GR-1 was withdrawn at 4 weeks, suggesting persistence of the GR-1 effects after cessation of therapy. Investigation of mechanisms showed a significant increase in the leptin:adiponectin plasma concentration ratio in rats subjected to coronary ligation, which was abrogated by GR-1. Metabonomic analysis showed differences between sham control and coronary artery ligated hearts particularly with respect to preservation of myocardial taurine levels. The study suggests that probiotics offer promise as a potential therapy for the attenuation of heart failure.

Polyamine Depletion Attenuates Isoproterenol-Induced Hypertrophy and Endoplasmic Reticulum Stress in Cardiomyocytes

Background/Aim: Polyamines (putrescine, spermidine and spermine) play an essential role in cell growth, differentiation and apoptosis. Hypertrophy is accompanied by an increase in polyamine synthesis and endoplasmic reticulum stress (ERS) in cardiomyocytes. The present study was undertaken to elucidate the molecular interactions between polyamines, ERS and cardiac hypertrophy. Methods: Myocardial hypertrophy was simulated by incubating cultured neonatal rat cardiomyocytes in 100 nM isoproterenol (ISO). Polyamine deletion was achieved using 0.5 mM difluoromethylornithine (DFMO). Hypertrophy was estimated using cell surface area measurements, total protein concentrations and atrial natriuretic peptide (ANP) gene expression. Apoptosis was measured using flow cytometry and transmission electron microscopy. Expression of ornithine decarboxylase (ODC) and spermidine/spermine N1-acetyltransferase (SSAT) were analyzed via real-time PCR and Western blotting. Protein expression of ERS and apoptosis factors were analyzed using Western blotting. Results: DFMO (0.5 mM and 2 mM) treatments significantly attenuated hypertrophy and apoptosis induced by ISO in cardiomyocytes. DFMO also decreased lactate dehydrogenase (LDH) and malondialdehyde (MDA) level in the culture medium. In addition, DFMO (0.5 mM) down regulated the expression of ODC, glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), cleaved caspase-12, and Bax and up regulated the expression of SSAT and Bcl-2. Finally, these changes were partly reversed by the addition of exogenous putrescine (0.5 mM). Conclusion: The data presented here suggest that polyamine depletion could inhibit cardiac hypertrophy and apoptosis, which is closely related to the ERS pathway.

Attenuated mitochondrial NADP+-dependent isocitrate dehydrogenase activity induces apoptosis and hypertrophy of H9c2 cardiomyocytes

Oxidative stress, characterized by the accumulation of reactive oxygen species (ROS), is known to have numerous detrimental effects on the myocardium such as the induction of apoptotic cell death, hypertrophy, fibrosis, dysfunction, and dilatation. Over the past several years, we have shown that mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDPm) functions as an antioxidant and anti-apoptotic protein by supplying NADPH to antioxidant systems. Here, we showed that transfection of H9c2 clonal myoblastic cells with small interfering RNA (siRNA) specific for IDPm markedly attenuated IDPm expression and substantially induced apoptosis, senescence, and hypertrophy as indicated by increased atrial natriuretic peptide (ANP) gene expression, a marker of cardiomyocyte hypertrophy, and a larger cell size. Knockdown of IDPm expression resulted in the modulation of cellular and mitochondrial redox status, mitochondrial function, and cellular oxidative damage. Taken together, our results suggest that the suppression of IDPm expression by siRNA induces apoptosis and hypertrophy of cultured cardiomyocytes through the disruption of cellular redox balance.

Right ventricular plasticity in a porcine model of chronic pressure overload

Ventricular-arterial coupling is a measure of the relationship between ventricular contractility and afterload. We sought to determine the relationship between ventricular-arterial coupling and right ventricular (RV) remodeling in a novel porcine model of progressive pulmonary hypertension (PH). Chronic PH was induced in pigs by ligation of the left pulmonary artery (PA) followed by 5 weekly injections of cyanoacrylate to progressively obstruct the right lower lobe arteries (PH group, n = 10). At 6 weeks, 5 PH animals underwent reperfusion of the left lung through conduit anastomosis to decrease RV afterload, whereas 5 other animals received no treatment. Five sham-operated piglets were used as controls. RV function was assessed using echocardiography and conductance catheterization. RV gene expression of beta-myosin heavy chain (β-MHC) and B-type natriuretic peptide (BNP) were quantified by polymerase chain reaction. At 6 weeks, compared with controls, the PH group had higher mean PA pressure (32 ± 6 vs 14 ± 2 mm Hg, p < 0.01). The increase in RV elastance was insufficient to compensate for the increase in pulmonary arterial elastance in the PH group and altered ventricular-arterial coupling occurred (0.65 ± 0.16 vs 1.28 ± 0.14, p < 0.01). The degree of ventricular-arterial uncoupling was related to RV enlargement and systolic dysfunction. Ventricular-arterial uncoupling and increased RV mass index were associated with up-regulation of β-MHC and BNP expression. Ventricular-arterial coupling is closely associated with ventricular remodeling and systolic function as well as contractile and BNP gene expression. Dynamic changes in myosin expression may determine RV work efficiency in PH.

Diabetes mellitus activates fetal gene program and intensifies cardiac remodeling and oxidative stress in aged spontaneously hypertensive rats

BackgroundThe combination of systemic arterial hypertension and diabetes mellitus (DM) induces greater cardiac remodeling than either condition alone. However, this association has been poorly addressed in senescent rats. Therefore, this study aimed to analyze the influence of streptozotocin-induced DM on ventricular remodeling and oxidative stress in aged spontaneously hypertensive rats (SHR).MethodsFifty 18 month old male SHR were divided into two groups: control (SHR, n = 25) and diabetic (SHR-DM, n = 25). DM was induced by streptozotocin (40 mg/kg, i.p.). After nine weeks, the rats underwent echocardiography and myocardial functional study in left ventricular (LV) isolated papillary muscle preparations. LV samples were obtained to measure myocyte diameters, interstitial collagen fraction, and hydroxyproline concentration. Gene expression of atrial natriuretic peptide (ANP) and α- and β-myosin heavy chain (MyHC) isoforms was evaluated by RT-PCR. Serum oxidative stress was assessed by measuring lipid hydroperoxide concentration and superoxide dismutase and glutathione peroxidase activities. Statistics: Student’s t test or Mann-Whitney test, p < 0.05.ResultsSHR-DM presented higher blood glucose (487 ± 29 vs. 89.1 ± 21.1 mg/dL) and lower body weight (277 ± 26 vs. 339 ± 38 g). Systolic blood pressure did not differ between groups. Echocardiography showed LV and left atrial dilation, LV diastolic and relative wall thickness decrease, and LV systolic and diastolic function impairment in SHR-DM. Papillary muscle study showed decreased myocardial contractility and contractile reserve in SHR-DM. Myocyte diameters and myocardial interstitial collagen fraction and hydroxyproline concentration did not differ between groups. Increased serum pro-oxidant activity and gene expression of ANP and β/α-MyHC ratio were observed in DM.ConclusionDiabetes mellitus induces cardiac dilation and functional impairment, increases oxidative stress and activates fetal gene program in aged spontaneously hypertensive rats.

Diabetes mellitus impairs cardiac remodeling and oxidative stress and activates fetal gene program in aged spontaneously hypertensive rats

Purpose: The combination of systemic arterial hypertension and Diabetes Mellitus (DM) induces greater cardiac remodeling than either condition alone. However, this association has been poorly addressed in senescent rats. Therefore, this study aimed to analyze the influence of streptozotocin-induced DM on ventricular remodeling and oxidative stress in aged Spontaneously Hypertensive Rats (SHR). Methods: Fifty 18 month old male SHR were divided into two groups: control (CTL, n=25) and diabetic (DM, n=25). DM was induced by streptozotocin (40 mg/kg, i.p.). After nine weeks, the rats underwent echocardiography and myocardial functional study in Left Ventricular (LV) isolated papillary muscle preparations. LV samples were obtained to measure myocyte diameters, interstitial collagen fraction, hydroxyproline concentration, and gene expression of Atrial Natriuretic Peptide (ANP) and α- and β-Myosin Heavy Chain (MyHC) isoforms. Serum oxidative stress was assessed by measuring lipid hydroperoxide concentration and superoxide dismutase and glutathione peroxidase activities. Statistics: Student's t test or Mann-Whitney test, p<0.05. Results: DM group presented higher blood glucose (487±29 vs. 89.1±21.1 mg/dL) and lower body weight (277±26 vs. 339±38 g). Systolic blood pressure did not differ between groups (CTL: 193±34; DM: 201±36 mmHg). Echocardiography showed LV and left atrial dilation, LV diastolic and relative wall thickness decrease, and LV systolic and diastolic function impairment in DM. Papillary muscle study showed decreased myocardial contractility and contractile reserve in DM. Myocyte diameters and myocardial interstitial collagen fraction and hydroxyproline concentration did not differ between groups. Increased serum pro-oxidant activity and gene expression of ANP (CTL: 1.00±0.38; DM: 1.88±0.69) and β/α-MyHC ratio (CTL: 1.20±0.60; DM: 2.26±0.94) were observed in DM. Conclusion: Diabetes mellitus induces cardiac dilation and functional impairment, increases oxidative stress and activates fetal gene program in aged spontaneously hypertensive rats. Support: CAPES and CNPq.

Right ventricular plasticity in a porcine model of chronic pulmonary hypertension

Purpose: Ventricular-arterial coupling is a measure of the relationship between ventricular contractility and afterload. In this study, we sought to determine the relationship between ventricular-arterial coupling and right ventricular (RV) adaptation to chronic pressure overload in a novel porcine model of progressive pulmonary hypertension (PH). Methods: Chronic PH was induced in pigs by ligation of the left pulmonary artery (PA) followed by five weekly injections of cyanoacrylate to progressively obstruct the right lower lobe arteries (PH group, n=10). At 6 weeks, 5 PH animals underwent a reperfusion of the left lung to durably decrease RV afterload, while other animals did not receive any treatment. Five sham-operated piglets were used as controls. RV function was assessed using echocardiography and pressure-volume loops analysis. RV gene expression of β-myosin heavy chain (β-MHC) and B-type natriuretic peptide (BNP) were quantified by reverse transcription polymerase chain reaction. Experimental design was approved by our Institutional Committee on Animal Welfare and the study followed the Principles of laboratory animal care. Results: At 6 weeks, compared to controls, the PH group had higher PA pressure (32±6 vs. 14±2 mmHg, p<0.01), RV end-diastolic area index (RVEDAI, 11.1±2.9 cm2 vs. 4.8±0.3 cm2, p<0.01), PA elastance (Ea, 0.90±0.45 vs. 0.29±0.06 ml/mmHg, p=0.01) and RV elastance (Ees, 0.53±0.14 vs. 0.34±0.06 ml/mmHg, p=0.01), and lower RV fractional area change (27±9% vs. 52±10%, p<0.01) (Table 1). The relationship between Ea and RV-PA coupling could be estimated through a curvilinear relationship (R2=0.90, p<0.01). RV-PA coupling was an important determinant of RVEDAI (R2=0.48, p<0.01), RVFAC (R2=0.84, p<0.01) and stroke volume index response to dobutamine (R2=0.56, p<0.01). Changes in RV-PA coupling were also strongly related to changes in stroke volume index response to dobutamine (R2=0.80, p<0.01). Ventricular-arterial coupling and RV mass index 6 weeks after PH surgical treatment were associated with down-regulation of β-MHC (R2=0.75, p<0.01 and R2=0.71, p<0.01 respectively) and BNP expression (R2=0.91, p<0.01 and R2=0.80, p<0.01) (Figure 1). Conclusions: A curvilinear relationship between pulmonary arterial elastance and RV-PA coupling suggests a faster transition towards uncoupling at the early stage of PH. Contractile protein expression and BNP expression are associated with ventricular mass and ventricular-arterial coupling in a porcine model of RV pressure overload.

GW24-e3020 Involvement of vascular peroxidase 1 in angiotensin II-induced H9c2 cells hypertrophy

ObjectivesOxidative stress induces hypertrophic gene expression and collagen deposition that mediates cardiac hypertrophy and myocardial fibrosis. Vascular peroxidase 1 (VPO1) is a new heme-containing peroxidase, which can utilise hydrogen peroxide...

AB0892 NT-PROBNP in ankylosing spondylitis patients undergoing TNF blockage therapy: Correlation with inflammatory status independent of cardiovascular disease

BackgroundInflammation may influence levels of N-terminal pro-brain natriuretic peptide (NT-proBNP)1-3 discrimination of this confounding variable is of particular interest in rheumatic diseases.4ObjectivesWe evaluated NT-proBNP levels in ankylosing spondylitis (AS) patients...

Cardiac Natriuretic Peptide Gene Expression and Plasma Concentrations During the First 72 Hours of Life in Piglets

Plasma measurement of cardiac natriuretic peptides constitutes promising markers of congenital heart disease. However, concentrations change rapidly and dramatically during the first days after delivery even in healthy neonates, which complicates clinical interpretation. It is unknown whether these changes in plasma concentrations are explained by corresponding changes in the cardiac gene expression. We quantified the chamber-specific mRNA levels of ANP (A-type natriuretic peptide) and BNP (B-type natriuretic peptide) and plasma pro-ANP and BNP-32 concentrations in healthy piglets during the first 72 hours of life (from 2 litters, n = 44). Chamber-specific ANP and BNP mRNA levels reflected hemodynamic neonate changes at birth but did not correlate with circulating natriuretic peptide concentrations. However, plasma pro-ANP and creatinine concentrations were closely correlated (P < .0001; r = 0.73). Plasma pro-ANP levels were highest on the day of delivery (5580 pmol/L [4320-6786] decreasing to 2484 pmol/L [1602-2898] after 72 hours, P < .0001). During the 72 hours, gel chromatography suggested that the translational products in circulation and in atrial tissue were immature, ie, unprocessed pro-ANP. In contrast to pro-ANP, BNP-32 plasma concentrations were low at delivery and peaked after 48 hours (12 [10.5-20.6] vs. 88.8 [71.7-101.4] pmol/L, P < .0001). To conclude, ANP and BNP gene expression differs considerably between cardiac chambers in the first 72 hours of life in healthy piglets, resembling the transition from fetal to neonate circulation. However, the cardiac gene expression does not explain plasma concentrations.

Pigs in space

Despite the common knowledge that experimental data from animal models cannot readily be translated into human disease, clinical trials are often based on translational research performed on species evolutionarily distant from humans. The troublesome task of extrapolating the findings from one species to another has haunted physiological experimentation since its early dawn, and the issue is still relevant in cardiovascular science with the common use of genetically modified mice. For instance, diabetic and ischemic changes in the myocardium are often pursued using in-vivo and in-vitro models mainly based on rodent cardiovascular physiology and cellular biology 1. The concern does not stop with only speculative reservation. Modern pharmacological studies most often test new drugs on small animals, resulting in a series of disappointments in human phase-3 trials 2,3, which has certainly cost us astronomical sums and may have even led to disease and death. The cardiac response to myocardial hypoxia should ideally be pursued in models that mimic human anatomy, biochemistry, and function in both health and disease. In this context, we suggest the porcine heart as the best model of choice in experimental cardiovascular research because of the following hallmarks: first and foremost, the coronary blood supply to the myocardium equals that of the normal human anatomy 4. In contrast, the functional end arteries do not supply the heart muscle in other mammalian species. Second, the cardiac production of natriuretic peptides, the gold standard endocrine markers of heart failure, differs markedly among mammalian hearts, wherein normal hormonal expression resides in the human and porcine atria 5,6 but is most dominant in the ventricular chambers in, for instance, rodents 7. Such intrinsic differences are likely to affect the endocrine cardiac response during the disease. Finally, porcine and human cardiac functions are similar, which facilitates direct interpretation to human medicine 8. Elucidation of several cardiovascular disease entities can be achieved using porcine models. For instance, we compared the neonate cardiovascular response of pigs in terms of cardiac natriuretic peptide gene expression and found patterns similar to those of neonate children. This opens up for the possibility of studying, for instance, the effects of gestational diabetes on neonate physiology. Moreover, cardiac congenital anomalies present in humans can easily be induced in pigs, and the devices for treating these conditions can even be tested on pigs 9. Another major disease entity for cardiovascular endocrinology is heart failure, in which natriuretic peptides have a central role in both pathobiological and clinical diagnosis. Accurate biochemical tools have been developed for this peptide system in pigs 10, which is not the case for other species, including mice. With an increasing appreciation and understanding of the porcine transcriptome 11,12, as well as genetically modified pigs already over the doorstep 13,14, cardiovascular endocrinology should consider the best choice of animal models for the studies on human cardiovascular pathophysiology. In this respect, a completely new pig model for human atherosclerosis has just been developed at our university by inducing overexpression of the gene for liver-specific proprotein convertase subtilisin/kexin type 9 (PCSK9), which causes severe hypercholesterolemia and human-like atherosclerosis 15. This model may easily prove valuable for several types of translational research on atherosclerosis and also in diabetes complications. For now, we would like to advocate that the use of pigs should be pursued more eagerly in elucidating human cardiovascular endocrinology (as pigs are only found in space in the Muppet Show) 16,17. Acknowledgements Conflicts of interest There are no conflicts of interest.