Cardiomyocyte Cross-sectional Area Research Articles

A role for galectin-3 in the development of early molecular alterations in short-term aortic stenosis

Aortic stenosis (AS) is characterized by pressure overload and causes left ventricular (LV) fibrosis and inflammation, two mechanisms that eventually lead to cardiac dysfunction. Galectin-3 (Gal-3), a β-galactoside-binding lectin, promotes cardiac remodelling. In the present study, we investigated the role of Gal-3in LV remodelling in patients with AS and the effects of Gal-3 blockade in rats subjected to short-term (6-week) supravalvular aortic banding (AS group). Myocardial biopsies were obtained from 25 patients with severe AS referred for aortic valve replacement and from necropsies of 11 cardiovascular disease-free control individuals. Gal-3 was up-regulated in myocardial biopsies from AS patients compared with controls. Gal-3 directly correlated with parameters assessing myocardial fibrosis and inflammation in AS patients. Normotensive AS animals presented decreased LV diastolic diameter compared with controls. At the histological level, AS rats exhibited a slight increase in LV cross-sectional area and LV wall thickness, and augmented cardiomyocyte width and cross-sectional area. AS animals presented enhanced cardiac Gal-3 expression, which paralleled higher myocardial fibrosis and inflammation. Cardiac Gal-3 was associated with fibrosis and inflammatory markers. Gal-3 pharmacological inhibition prevented the increase in cardiac Gal-3 and normalized histological and molecular alterations in AS rats. In short-term AS, the increase in myocardial Gal-3 expression was associated with cardiac fibrosis and inflammation, alterations that were prevented by Gal-3 blockade. These data suggest that Gal-3 inhibition could be a novel therapeutic approach in the prevention of AS-associated early pathological cardiac remodelling.

Pinocembrin ex vivo preconditioning improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats

Pulmonary hypertension is still not curable and the available current therapies can only alleviate symptoms without hindering the progression of disease. The present study was directed to investigate the possible modulatory effect of pinocembrin on endothelial progenitor cells transplanted in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60mg/kg). Endothelial progenitor cells were in vitro preconditioned with pinocembrin (25mg/L) for 30min before being i.v. injected into rats 2weeks after monocrotaline administration. Four weeks after monocrotaline administration, blood pressure, electrocardiography and right ventricular systolic pressure were recorded. Rats were sacrificed and serum was separated for determination of endothelin-1 and asymmetric dimethylarginine levels. Right ventricles and lungs were isolated for estimation of tumor necrosis factor-alpha and transforming growth factor-beta contents as well as caspase-3 activity. Moreover, protein expression of matrix metalloproteinase-9 and endothelial nitric oxide synthase in addition to myocardial connexin-43 was assessed. Finally, histological analysis of pulmonary arteries, cardiomyocyte cross-sectional area and right ventricular hypertrophy was performed and cryosections were done for estimation of cell homing. Preconditioning with pinocembrin provided a significant improvement in endothelial progenitor cells’ effect towards reducing monocrotaline-induced elevation of inflammatory, fibrogenic and apoptotic markers. Furthermore, preconditioned cells induced a significant amelioration of endothelial markers and cell homing and prevented monocrotaline-induced changes in right ventricular function and histological analysis compared with native cells alone. In conclusion, pinocembrin significantly improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats.

Apocynin attenuates left ventricular remodeling in diabetic rabbits.

IntroductionNicotinamide adenine dinucleotide phosphate (NADPH) oxidases are responsible for the generation of reactive oxygen species, producing vascular and myocardial dysfunction in diabetes mellitus. However, the potential benefits of the NADPH oxidase inhibitor, apocynin, on left ventricular (LV) remodeling remain unknown.ResultsIn the diabetic group, interventricular septal thickness and left ventricular posterior wall thickness were markedly increased compared to control. These changes were accompanied by increased LV cardiomyocyte cross-sectional area and greater degree of interstitial fibrosis. NO, myeloperoxidase, and malonaldehyde levels in the serum were significantly increased Moreover, protein expression levels of rac1, nuclear factor-κB, transforming growth factor-β, p38, P-p38, and metalloproteinase-9 were also raised. Apocynin treatment prevented all of these structural, histological and biochemical changes and additionally increased superoxide dismutase levels.MethodsThirty Japanese rabbits were randomized into three groups: control, alloxan-induced diabetes with and without apocynin treatment at 15 mg/kg/day for 8 weeks (n = 10 for each group). Echocardiography was performed and hemodynamics were assessed by carotid and LV catheterization. LV cardiomyocyte cross-sectional area and interstitial fibrosis were evaluated by histology. Serum nitric oxide (NO), malonaldehyde, myeloperoxidase, superoxide dismutase (SOD) levels, and activity of LV tissue NADPH oxidases was assessed. Expression of proteins involved in pro-inflammatory and pro-fibrotic signaling were determined by Western blotting.ConclusionsInhibition of NADPH oxidase using apocynin is an effective upstream therapy for preventing diabetes-induced adverse remodeling of the left ventricular myocardium.

Hydrogen Sulfide Inhibits High-Salt Diet-Induced Myocardial Oxidative Stress and Myocardial Hypertrophy in Dahl Rats.

The study aimed to examine the protective effect of hydrogen sulfide (H2S) on high-salt-induced oxidative stress and myocardial hypertrophy in salt-sensitive (Dahl) rats. Thirty male Dahl rats and 40 SD rats were included in the study. They were randomly divided into Dahl control (Dahl + NS), Dahl high salt (Dahl + HS), Dahl + HS + NaHS, SD + NS, SD + HS, SD + HS + NaHS, and SD + HS + hydroxylamine (HA). Rats in Dahl + NS and SD + NS groups were given chow with 0.5% NaCl and 0.9% normal saline intraperitoneally daily. Myocardial structure, α-myosin heavy chain (α-MHC) and β-myosin heavy chain (β-MHC) expressions were determined. Endogenous myocardial H2S pathway and oxidative stress in myocardial tissues were tested. Myocardial H2S pathway was downregulated with myocardial hypertrophy featured by increased heart weight/body weight and cardiomyocytes cross-sectional area, decreased α-MHC and increased β-MHC expressions in Dahl rats with high-salt diet (all P < 0.01), and oxidative stress in myocardial tissues was significantly activated, demonstrated by the increased contents of hydroxyl radical, malondialdehyde and oxidized glutathione and decreased total antioxidant capacity, carbon monoxide, catalase, glutathione, glutathione peroxidase, superoxide dismutase (SOD) activities and decreased SOD1 and SOD2 protein expressions (P < 0.05, P < 0.01). However, H2S reduced myocardial hypertrophy with decreased heart weight/body weight and cardiomyocytes cross-sectional area, increased α-MHC, decreased β-MHC expressions and inhibited oxidative stress in myocardial tissues of Dahl rats with high-salt diet. However, no significant difference was found in H2S pathway, myocardial structure, α-MHC and β-MHC protein and oxidative status in myocardial tissues among SD + NS, SD + HS, and SD + HS + NaHS groups. HA, an inhibitor of cystathionine β-synthase, inhibited myocardial H2S pathway (P < 0.01), and stimulated myocardial hypertrophy and oxidative stress in SD rats with high-salt diet. Hence, H2S inhibited myocardial hypertrophy in high salt-stimulated Dahl rats in association with the enhancement of antioxidant capacity, thereby inhibiting oxidative stress in myocardial tissues.

Choline ameliorates cardiovascular damage by improving vagal activity and inhibiting the inflammatory response in spontaneously hypertensive rats

Autonomic dysfunction and abnormal immunity lead to systemic inflammatory responses, which result in cardiovascular damage in hypertension. The aim of this report was to investigate the effects of choline on cardiovascular damage in hypertension. Eight-week-old male spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats were intraperitoneally injected with choline or vehicle (8 mg/kg/day). After 8 weeks, choline restored the cardiac function of the SHRs, as evidenced by decreased heart rate, systolic blood pressure, left ventricle systolic pressure, and ±dp/dtmax and increased ejection fraction and fractional shortening. Choline also ameliorated the cardiac hypertrophy of the SHRs, as indicated by reduced left ventricle internal dimensions and decreased cardiomyocyte cross-sectional area. Moreover, choline improved mesenteric arterial function and preserved endothelial ultrastructure in the SHRs. Notably, the protective effect of choline may be due to its anti-inflammatory effect. Choline downregulated expression of interleukin (IL)-6 and tumour necrosis factor-α and upregulated IL-10 in the mesenteric arteries of SHRs, possibly because of the inhibition of Toll-like receptor 4. Furthermore, choline restored baroreflex sensitivity and serum acetylcholine level in SHRs, thus indicating that choline improved vagal activity. This study suggests that choline elicits cardiovascular protective effects and may be useful as a potential adjunct therapeutic approach for hypertension.

Serelaxin treatment promotes adaptive hypertrophy but does not prevent heart failure in experimental peripartum cardiomyopathy.

AimsPeripartum cardiomyopathy (PPCM) is a systolic left ventricular dysfunction developing in the peripartum phase in previously healthy women. Relaxin-2 is a pregnancy hormone with potential beneficial effects in heart failure patients. We evaluated Relaxin-2 as a potential diagnostic marker and/or a therapeutic agent in PPCM.Methods and resultsIn healthy peripartum women, serum Relaxin-2 levels (measured by ELISA in the second half of pregnancy) were elevated showing a decreasing trend in the first postpartum week and returned to non-pregnant levels thereafter. In PPCM patients diagnosed in the first postpartum week, serum Relaxin-2 levels were lower compared to healthy postpartum stage-matched controls. In PPCM patients diagnosed later (0.5–10 months postpartum) Relaxin-2 levels were in the range of non-pregnant controls and not different from healthy postpartum stage-matched controls. In mice, serum Relaxin-1 (functional equivalent of human Relaxin-2) was increased late in pregnancy and rapidly cleared in the first postpartum week. In mice with PPCM due to a cardiomyocyte-specific knockout of STAT3 (CKO) neither low nor high dose of recombinant Relaxin-2 (serelaxin, sRlx-LD: 30 µg/kg/day; sRlx-HD: 300 µg/kg/day) affected cardiac fibrosis, inflammation and heart failure but sRlx-HD increased capillary/cardiomyocyte ratio. sRlx-HD significantly increased heart/body weight ratio and cardiomyocyte cross-sectional area in postpartum CKO and wild-type mice without changing the foetal gene expression program (ANP or β-MHC). sRlx-HD augmented plasma Prolactin levels in both genotypes, which induced cardiac activation of STAT5. In vitro analyses showed that Prolactin induces cardiomyocyte hypertrophy via activation of STAT5.ConclusionAlthough Relaxin-2 levels seemed lower in PPCM patients diagnosed early postpartum, we observed a high pregnancy-related variance of serum Relaxin-2 levels peripartum making it unsuitable as a biomarker for this condition. Supplementation with sRlx may contribute to angiogenesis and compensatory hypertrophy in the diseased heart, but the effects are not sufficient to prevent heart failure in an experimental PPCM model.

Sodium glucose transporter 2 (SGLT2) inhibition with empagliflozin improves cardiac diastolic function in a female rodent model of diabetes

Obese and diabetic individuals are at increased risk for impairments in diastolic relaxation and heart failure with preserved ejection fraction. The impairments in diastolic relaxation are especially pronounced in obese and diabetic women and predict future cardiovascular disease (CVD) events in this population. Recent clinical data suggest sodium glucose transporter-2 (SGLT2) inhibition reduces CVD events in diabetic individuals, but the mechanisms of this CVD protection are unknown. To determine whether targeting SGLT2 improves diastolic relaxation, we utilized empagliflozin (EMPA) in female db/db mice. Eleven week old female db/db mice were fed normal mouse chow, with or without EMPA, for 5 weeks. Blood pressure (BP), HbA1c and fasting glucose were significantly increased in untreated db/db mice (DbC) (P < 0.01). EMPA treatment (DbE) improved glycemic indices (P < 0.05), but not BP (P > 0.05). At baseline, DbC and DbE had already established impaired diastolic relaxation as indicated by impaired septal wall motion (>tissue Doppler derived E′/A′ ratio) and increased left ventricular (LV) filling pressure (<E/E′ ratio). Although these abnormalities persisted throughout the study period in DbC, diastolic function improved with EMPA treatment. In DbC, myocardial fibrosis was accompanied by increased expression of profibrotic/prohypertrophic proteins, serum/glucocorticoid regulated kinase 1 (SGK1) and the epithelial sodium channel (ENaC), and the development of these abnormalities were reduced with EMPA. DbC exhibited eccentric LV hypertrophy that was slightly improved by EMPA, indicated by a reduction in cardiomyocyte cross sectional area. In summary, EMPA improved glycemic indices along with diastolic relaxation, as well as SGK1/ENaC profibrosis signaling and associated interstitial fibrosis, all of which occurred in the absence of any changes in BP.

Nobiletin, a Polymethoxy Flavonoid, Protects Against Cardiac Hypertrophy Induced by Pressure-Overload via Inhibition of NAPDH Oxidases and Endoplasmic Reticulum Stress

Background/Aims: An increase in oxidative stress has been implicated in the pathophysiology of pressure-overload induced cardiac hypertrophy. Nobiletin (NOB), extracted from the fruit peel of citrus, possesses anti-oxidative property. Our study aimed to investigate the protective role of NOB in the progression of cardiac hypertrophy in vivo and in vitro. Methods: Mice received aortic banding (AB) operation to induce cardiac hypertrophy. Experimental groups were as follows: sham+vehicle (VEH/SH), sham+NOB (NOB/SH), AB+vehicle (VEH/AB), and AB+ NOB (NOB/AB). Animals (n = 15 per group) were treated with vehicle or NOB (50 mg/kg) for 4 weeks after disease onset. Results: NOB prevented cardiac hypertrophy induced by aortic banding (AB), as assessed by the cross-sectional area of cardiomyocytes, heart weight-to-body weight ratio, gene expression of hypertrophic markers and cardiac function. In addition, NOB supplementation blunted the increased expression of NAPDH oxidase (NOX) 2 and NOX4 and mitigated endoplasmic reticulum (ER) stress and myocyte apoptosis in cardiac hypertrophy. Furthermore, NOB treatment attenuated the neonatal rat cardiomyocyte (NRCM) hypertrophic response stimulated by phenylephrine (PE) and alleviated ER stress. However, our data showed that NOB dramatically inhibited NOX2 expression but not NOX4 in vitro. Finally, we found that knockdown of NOX2 attenuated ER stress in NRCMs stimulated by PE. Conclusions: Inhibition of oxidative and ER stress by NOB in the myocardium may represent a potential therapy for cardiac hypertrophy. Moreover, there is a direct role of NOX2 in regulating ER stress stimulated by PE.

Ginsenoside Rb1 improves cardiac function and remodeling in heart failure.

We investigated the effect of ginsenoside Rb1 on cardiac function and remodeling in heart failure (HF). Four weeks after HF induction, the rats were administrated with ginsenoside Rb1 (35 and 70 mg/kg) and losartan (4.5 mg/kg) for 8 weeks. Losartan was used as a positive control. Cardiac function was assessed by measuring hemodynamic parameters. Histological changes were analyzed by HE and Masson’s trichrome staining. Cardiac hypertrophy, fibrosis, mitochondrial membrane potential and glucose transporter type 4 (GLUT4) levels were evaluated. In the present study, high dose of (H−) ginsenoside Rb1 decreased heart rate, improved cardiac function and alleviated histological changes induced by HF. H-ginsenoside Rb1 attenuated cardiac hypertrophy and myocardial fibrosis by decreasing left ventricular (LV) weight/heart weight ratio and cardiomyocyte cross-sectional area and reducing the levels of atrial natriuretic factor (ANF), β-myosin heavy chain (β-MHC), periostin, collagen I, Angiotensin II (Ang II), Angiotensin converting enzyme (ACE) and Ang II type 1 (AT1) receptor. Moreover, H-ginsenoside Rb1 decreased mitochondrial membrane potential and enhanced the translocation of GLUT4 to plasma membrane. The TGF-β1/Smad and ERK signaling pathways were inhibited and the Akt pathway was activated. These findings suggest that ginsenoside Rb1 might restore cardiac/mitochondrial function, increase glucose uptake and protect against cardiac remodeling via the TGF-β1/Smad, ERK and Akt signaling pathways.

Attenuation of Low Ambient Temperature-Induced Myocardial Hypertrophy by Atorvastatin via Promoting Bcl-2 Expression

Background/Aims: It is well documented that myocardial hypertrophy is associated with low ambient temperature. Atorvastatin (Atv) has been shown to protect against atherosclerosis, cardiac fibrosis, ischemia/reperfusion injury, etc. In this study, we aim to determine whether atorvastatin is effective in the treatment of myocardial hypertrophy induced by cold exposure and to shed light on underlying mechanism. Methods: The mice aged 4-week were randomized to Control (Ctl) group (raised at room temperature), Cold group (raised at 3-5ºC) and Atv treatment group (raised at 3-5ºC followed by 10mg/kg/day Atv infusion). Echocardiography (ECG), HE, TUNEL and Masson’s trichrome staining, and Transmission electronic microscopy were performed to analyze cardiac function, myocardial hypertrophy, cardiac fibrosis, apoptosis and cardiomyocyte ultrastructure, respectively. Western blot was carried out to determine the involvement of MAPK and apoptosis pathways. Results: Exposure of mice to low temperature induced myocardial hypertrophic growth characterized by the elevation of heart/body weight index and heart weight /tibia length index, compared with control mice. Atv treatment attenuated cardiac hypertrophy induced by cold exposure; Atv also attenuated the increase of cross-sectional area of cardiomyocytes and cardiac collagen content fraction in mice exposed to cold. ECG showed that the decline of cardiac functions including the elevated left ventricular systolic/diastolic internal dimension (LVIDs/d) and fractional shortening (FS) in mice with cold exposure was also inhibited by Atv treatment. Transmission electronic microscopy uncovered that Atv attenuated mitochondrial injury induced by cold exposure in mice. In addition, systolic blood pressure was gradually increased in mice exposed to cold temperature, and Atv treatment significantly inhibited the elevation of blood pressure in cold-treated mice. Mechanistically, mitogen-activated protein kinase (MAPK) signal was not altered in mice exposed to cold, and Atv did not affect MAPK signal in cold-treated mice. But Atv mitigated the reduction of Bcl-2/Bax level in heart of cold-treated mice. Conclusion: Atv attenuated myocardial hypertrophy induced by cold exposure through inhibiting the downregulation of Bcl-2 in heart. It may provide a novel strategy for low temperature-induced myocardial hypertrophy treatment.

Let-7a Is an Antihypertrophic Regulator in the Heart via Targeting Calmodulin.

Background: MicroRNAs (miRNAs) have been emerged as important regulator in a multiple of cardiovascular disease, including arrhythmia, cardiac hypertrophy and fibrosis, and myocardial infarction. The aim of this study was to investigate whether miRNA let-7a has antihypertrophic effects in angiotensin II (AngII)-induced cardiac hypertrophy.Methods: Neonatal rat ventricular myocytes (NRVMs) were exposed to AngII for 36 h as a cellular model of hypertrophy; subcutaneous injection of AngII for 2 weeks was used to establish a mouse model of cardiac hypertrophy in vivo study. Cell surface area (CSA) was measured by immunofluorescence cytochemistry; expression of hypertrophy-related genes ANP, BNP, β-MHC was detected by Real-time PCR; luciferase activity assay was performed to confirm the miRNA's binding site in the calmodulin (CaM) gene; CaM protein was detected by Western blot; the hypertrophy parameters were measured by echocardiographic assessment.Results: The expression of let-7a was decreased in AngII-induced cardiac hypertrophy in vitro and in vivo. Overexpression of let-7a attenuated AngII-induced increase of cell surface area and repressed the increased mRNA levels of ANP, BNP and β-MHC. Dual-luciferase reporter assay showed that let-7a could bind to the 3'UTR of CaM 1 gene. Let-7a downregulated the expression of CaM protein. In vivo, let-7a produced inhibitory effects on cardiac hypertrophy, including the downregulation of cross-sectional area of cardiomyocytes in mouse heart, the reduction of IVSD and LVPWD, the suppression of hypertrophy marker genes ANP, BNP, β-MHC mRNA level, and the downregulation of CaM protein level.Conclusions: let-7a possesses a prominent anti-hypertrophic property by targeting CaM genes. The findings provide new insight into molecular mechanism of cardiac hypertrophy.

The myocardial remodeling at ischemic chronic heart failure: the features of Ivabradine influence in experimental model

Aim. Experimental study of Ivabradine influence on myocardial remodeling in patients with ischemic chronic heart failure.Material and Methods. The ischemic model of heart failure (HF) was modeled in 30 mature rats by isoproterenol injection. All animals were divided into 3 groups (10 each): I – control; II – with model of HF; III – with HF model and Ivabradine usage. For calculation of metric characteristics of the cardiomyocytes UTHSCSA Image Tool® for Windows® (version 2.00) program equipment in interactive regime was used. Morphometric analysis was made by point-based calculation method with 72-network. Statistical analysis was made by standard program equipment “Statistica for Windows12.0” (StatSoft,Tulsa,OK,USA).Results. In experimental animals with model of ischemic HF the substantial hypertrophy of cardiomyocytes was observed. This process was characterized by increase in cardiomyocytes cross-sectional area, cross-sectional area of nuclei, decrease of nucleus-to-cytoplasm ratio and some discoordination of this parameter. In case of Ivabradine prescription we have noted reduction in myocardial hypertrophy processes with the following sings: decrease in mean cardiomyocytes cross-sectional area in 1.31 times (p<0,05), and mean cross-sectional area of nuclei – in 1.41 times (p<0,05).Conclusions. 1. In case of ischemic heart failure the substantial hypertrophy of cardiomyocytes with increase in mean parameters of their nuclei volume and nucleus-to-cytoplasm ratio disturbances were observed.2. Ivabradine caused a mild regression of myocardial remodeling, as evidenced by a decrease in the degree of cardiomyocytes and their nuclei hypertrophy, severity of parenchyma dystrophy and fibrosis of heart muscle.

Cardiac Mitochondrial Respiratory Dysfunction and Tissue Damage in Chronic Hyperglycemia Correlate with Reduced Aldehyde Dehydrogenase-2 Activity.

Aldehyde dehydrogenase (ALDH) 2 is a mitochondrial isozyme of the heart involved in the metabolism of toxic aldehydes produced from oxidative stress. We hypothesized that hyperglycemia-mediated decrease in ALDH2 activity may impair mitochondrial respiration and ultimately result in cardiac damage. A single dose (65 mg/kg; i.p.) streptozotocin injection to rats resulted in hyperglycemia with blood glucose levels of 443 ± 9 mg/dl versus 121 ± 7 mg/dl in control animals, p<0.0001, N = 7–11. After 6 months of diabetes mellitus (DM) induction, the rats were sacrificed after recording the functionality of their hearts. Increase in the cardiomyocyte cross sectional area (446 ± 32 μm2 Vs 221 ± 10 μm2; p<0.0001) indicated cardiac hypertrophy in DM rats. Both diastolic and systolic dysfunctions were observed with DM rats compared to controls. Most importantly, myocardial ALDH2 activity and levels were reduced, and immunostaining for 4HNE protein adducts was increased in DM hearts compared to controls. The mitochondrial oxygen consumption rate (OCR), an index of mitochondrial respiration, was decreased in mitochondria isolated from DM hearts compared to controls (p<0.0001). Furthermore, the rate of mitochondrial respiration and the increase in carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP)-induced maximal respiration were also decreased with chronic hyperglycemia. Chronic hyperglycemia reduced mitochondrial OXPHOS proteins. Reduced ALDH2 activity was correlated with mitochondrial dysfunction, pathological remodeling and cardiac dysfunction, respectively. Our results suggest that chronic hyperglycemia reduces ALDH2 activity, leading to mitochondrial respiratory dysfunction and consequently cardiac damage and dysfunction.

Effects of danshensu on cardiac function and myocardial fibrosis in pressure-overloaded mice

Objective To observe the effect of Danshensu (DSS) on cardiac function and myocardial fibrosis in pressure-overloaded mice. Methods C57BL/6 male mice were randomly divided into four groups: Sham-Saline, Sham-DSS, TAC-Saline and TAC-DSS. Mice ventricular remodeling model were established by transverse aortic constriction (TAC) operation. One week later, the mice were fed with DSS or Saline for 7 weeks. After echocardiographic evaluation, cardiomyocyte cross-sectional area and myocardial fibrosis were determined by hematoxylin and eosin (HE) and Masson staining, respectively. Western blotting analysis was performed to detect the expression of transforming growth factor-β1 (TGF-β1)/Smad signaling pathway related proteins. Results Compared with Sham-Saline group, the left ventricular ejection fraction and fraction shortening in TAC-Saline group were reduced [(48.19±1.11)% vs. (80.78±1.30)%; (24.36±0.63)% vs. (42.87±1.09)%, P<0.05], which could be improved by DSS [(57.35±1.09)% and (29.88±0.68)%, respectively, P<0.05]. HE staining indicated an enlargement in cardiomyocyte cross-sectional area after TAC [(379±25) μm2 vs. (192±12) μm2,P<0.05], which could be ameliorated by DSS [(264±18) μm2,P<0.05]. Masson staining demonstrated that the degree of myocardial fibrosis was increased following TAC [(11.34±1.43)% vs. (2.18±0.14)%, P<0.05], which could be mitigated by DSS intervention[(5.26±1.17)%, P<0.05]. In addition to a reduction in Smad7 protein content, an increase in the protein level of p-Smad2, p-Smad3 and TGF-β1 were also observed in TAC-Saline group compared to Sham-Saline group (P<0.05); compared with TAC-Saline group, TAC-DSS group showed a reduced expression of p-Smad2, p-Smad3 and TGF-β1 and an increased expression of Smad7 (P<0.05). Conclusion DSS may ameliorate myocardial fibrosis via TGF-β1/Smad signaling pathway, thus improving the cardiac function and ventricular remodeling after pressure overload. Key words: Danshensu; Transverse aortic constriction; transforming growth factor-β1/Smad; Myocardial fibrosis

Chronic Hypobaric Hypoxia Induces Right Ventricular Hypertrophy and Apoptosis in Rats: Therapeutic Potential of Nanocurcumin in Improving Adaptation.

Nehra, Sarita, Varun Bhardwaj, Santosh Kar, and Deepika Saraswat. Chronic hypobaric hypoxia induces right ventricular hypertrophy and apoptosis in rats: therapeutic potential of nanocurcumin in improving adaptation. High Alt Med Biol. 17:342-352, 2016.-a sustained work load on the right heart on ascent to high altitudes promotes right ventricular hypertrophy (RVH), which eventually undergoes decompensation and promotes pathological damage. However, the exact set of events leading to damage remains unidentified. Curcumin is a natural antioxidant and antihypertrophic agent, but it has poor biostability. Nanotized curcumin (nanocurcumin) has emerged as a promising agent with improved biostability while retaining the therapeutic properties of curcumin. The present study aimed at analyzing the therapeutic properties of nanocurcumin in ameliorating cardiac damage due to chronic hypobaric hypoxia (HH)-induced RVH in comparison to curcumin. Sprague-Dawley rats exposed to HH (25,000 feet, effective oxygen fraction in air [FIO2] ∼0.08, temperature 28°C ± 1°C, relative humidity 55% ± 2% for 3, 7, 14, and 21 days) developed RVH with increased interstitial collagen content, Fulton's index, and cardiomyocyte cross-sectional area while upregulating atrial natriuretic peptide. Tissue damage due to apoptotic cell death was evident by cytochrome-c/caspase-3 activation and TUNEL assay. Concomitant modulation of cyclic guanosine monophosphate (cGMP)/cGK-1, calmodulin-dependent protein kinase II (CaMkinase II), and intracellular calcium levels with increased free radical-induced damage and lipid peroxidation further contributed to the right heart pathology. Nanocurcumin supplementation decreased HH-induced RVH and apoptosis while modulating cardiac cGMP/cGK-1 signaling, and maintaining CaMkinase II, intracellular calcium levels and redox status better than curcumin. Nanocurcumin-mediated antiapoptotic effects might have benefited residents and sojourners at high altitude in preventing hypoxic cardiac damage.

Abstract P112: Decreased α-Myosin Expression is Associated with Left Ventricular Hypertrophy in Hypertensive Caribbean Vervets

Caribbean vervets ( Chlorocebus aethiops sabeus ) develop hypertension (HT; Systolic Blood Pressure ≥ 140 mmHg) in over 30% (125/345) of the outbred population. Elevated total peripheral resistance in HT increases cardiac afterload, which may lead to left ventricular hypertrophy (LVH) and cardiac remodeling. We hypothesize that prolonged spontaneous HT is associated with LVH, cardiac and aortic fibrosis, as well as differential transcription of myocardial contractile proteins. Vervets were characterized as HT (SBP = 170 ± 25.3 mmHg; n=125) or normotensive (NT, SBP = 99 ± 14.5 mmHg; n=148) using forearm plethysmography (ketamine sedated;15 mg/kg i.m.). Cardiomyocyte cross-sectional area was greater in HT compared to NT animals (HT 283 ± 52 μm 2 , n=9 vs NT 114 ± 8 μm 2 , n=10; p&lt;0.01). Average collagen stained as a function of tissue area was similar in left ventricular myocardium of HT and NT animals (HT 14.17 ± 3.13% or 0.17/1.21 mm 2 , n=9 vs NT 12.22 ± 0.80% or 0.16/1.27 mm 2 , n=10; p&gt;0.05). Aortic adventia collagen area was greater in HT compared to NT vervets (HT 66.12 ± 4.22% or 0.60/0.90 mm 2 , n=6 vs NT 54.53 ± 2.21% or 0.56/1.02 mm 2 , n=10; p&lt;0.05). Total tissue collagen was estimated using a hydroxyproline assay. Collagen content was not different between HT and NT vervets for left ventricular myocardium (HT 194.02 ± 8.61 μg/mL, n=11 vs NT 201.70 ± 18.89 μg/mL, n=10; p=0.71) or aorta (HT 745.64 ± 44.49 μg/mL, n=11 vs NT 668.39 ± 31.06 μg/mL, n=11; p=0.17). Myosin gene expression (α and β) was estimated using RT-PCR of mRNA in left ventricular myocardium of NT (SBP = 98.91 ±10.89 mmHg; n=20) and HT (SBP = 171.51 ± 30.28 mmHg; n=17) vervets. α-myosin was downregulated in HT compared to NT vervets (HT RQ = 0.10 ± 0.03 vs. NT RQ = 0.22 ± 0.04; p&lt;0.05), while β-myosin expression was not different (HT RQ = 0.22 ± 0.17 vs. NT RQ = 0.20 ± 0.16; p=0.83). Thus, spontaneous HT in outbred vervets induces LVH in response to factors other than cardiac fibrosis. Myosin gene expression may shift from α-myosin to other contractile protein isoforms, characteristic of human heart failure. In this nonhuman primate model, HT does not induce significant aortic fibrosis that may occur in aged animals. Future studies will further characterize contractile and pro-inflammatory proteins in LVH of spontaneous HT vervets.

Abstract P166: The Effect of a Muscadine Grape Extract on Angiotensin II-Induced Hypertension and Cardiac Damage

Muscadine grapes, indigenous to the southeastern United States, are a dietary source of polyphenols, such as ellagic acid, quercetin, and resveratrol, which have both anti-inflammatory and antioxidant properties. Preclinical studies show that ground muscadine grape skins and seeds have anti-cancer effects, suggesting that supplementation with a muscadine grape extract (MGE) may serve as a chemotherapeutic or chemopreventive agent. As cancer patients often present with hypertension, diabetes, and other vascular pathologies, it is imperative to determine the effect of a muscadine grape supplement on these underlying comorbidities. The goal of this study was to determine whether MGE administered in the drinking water will exacerbate or improve hypertension and cardiac damage. Sprague-Dawley rats receiving a 4-week infusion of Ang II via subcutaneous osmotic mini-pump (24 μg/kg/h) had a significant increase in systolic blood pressure (123.1 ± 2.3 mm Hg in control vs. 213.1 ± 6.8 mm Hg in Ang II-treated; n=8; p &lt; 0.0001). MGE supplementation had no effect on blood pressure or gross cardiac hypertrophy in either normotensive or hypertensive rats. Additionally, MGE did not alter stroke volume or cardiac output, measured by VEVO ultrasound. However, MGE ameliorated the Ang-II induced decrease in diastolic function, as measured by the E/E’ ratio (19.9 ± 0.8 in control, 28.1 ± 1.1 in Ang II-treated rats, 22.3 ± 2.0 in Ang II/MGE-treated rats; p &lt; 0.05). Co-treatment with MGE also significantly reduced the Ang II-mediated increase in cardiomyocyte cross-sectional area (340.5 ± 12.0 μm 2 in control, 423.2 ± 17.1 μm 2 in Ang II-treated rats, and 342.6 ± 13.2 μm 2 in Ang II/MGE-treated rats, p &lt; 0.01). MGE supplementation of Ang II-treated rats decreased interstitial cardiac fibrosis, measured by Picrosirius red staining (1.0 ± 0.1% in control, 2.0 ± 0.2% in Ang II-treated rats and 1.4 ± 0.1% in Ang II/MGE-treated rats, p &lt; 0.05). These results demonstrate that treatment with MGE does not exacerbate hypertension or hypertension-induced cardiac damage but ameliorates cardiac hypertrophy, suggesting that MGE supplementation has an acceptable safety profile for use as an anti-cancer agent in hypertensive patients and may be used to treat cardiac hypertrophy and damage.

Cardiac-restricted Overexpression of TRAF3 Interacting Protein 2 (TRAF3IP2) Results in Spontaneous Development of Myocardial Hypertrophy, Fibrosis, and Dysfunction

TRAF3IP2 (TRAF3 interacting protein 2; previously known as CIKS or Act1) is a key intermediate in the normal inflammatory response and the pathogenesis of various autoimmune and inflammatory diseases. Induction of TRAF3IP2 activates IκB kinase (IKK)/NF-κB, JNK/AP-1, and c/EBPβ and stimulates the expression of various inflammatory mediators with negative myocardial inotropic effects. To investigate the role of TRAF3IP2 in heart disease, we generated a transgenic mouse model with cardiomyocyte-specific TRAF3IP2 overexpression (TRAF3IP2-Tg). Echocardiography, magnetic resonance imaging, and pressure-volume conductance catheterization revealed impaired cardiac function in 2-month-old male transgenic (Tg) mice as evidenced by decreased ejection fraction, stroke volume, cardiac output, and peak ejection rate. Moreover, the male Tg mice spontaneously developed myocardial hypertrophy (increased heart/body weight ratio, cardiomyocyte cross-sectional area, GATA4 induction, and fetal gene re-expression). Furthermore, TRAF3IP2 overexpression resulted in the activation of IKK/NF-κB, JNK/AP-1, c/EBPβ, and p38 MAPK and induction of proinflammatory cytokines, chemokines, and extracellular matrix proteins in the heart. Although myocardial hypertrophy decreased with age, cardiac fibrosis (increased number of myofibroblasts and enhanced expression and deposition of fibrillar collagens) increased progressively. Despite these adverse changes, TRAF3IP2 overexpression did not result in cell death at any time period. Interestingly, despite increased mRNA expression, TRAF3IP2 protein levels and activation of its downstream signaling intermediates remained unchanged in the hearts of female Tg mice. The female Tg mice also failed to develop myocardial hypertrophy. In summary, these results demonstrate that overexpression of TRAF3IP2 in male mice is sufficient to induce myocardial hypertrophy, cardiac fibrosis, and contractile dysfunction.

Regulation of myoglobin in hypertrophied rat cardiomyocytes in experimental pulmonary hypertension.

A major problem in chronic heart failure is the inability of hypertrophied cardiomyocytes to maintain the required power output. A Hill-type oxygen diffusion model predicts that oxygen supply is limiting in hypertrophied cardiomyocytes at maximal rates of oxygen consumption and that this limitation can be reduced by increasing the myoglobin (Mb) concentration. We explored how cardiac hypertrophy, oxidative capacity, and Mb expression in right ventricular cardiomyocytes are regulated at the transcriptional and translational levels in an early stage of experimental pulmonary hypertension, in order to identify targets to improve the oxygen supply/demand ratio. Male Wistar rats were injected with monocrotaline to induce pulmonary hypertension (PH) and right ventricular heart failure. The messenger RNA (mRNA) expression levels per nucleus of growth factors insulin-like growth factor-1Ea (IGF-1Ea) and mechano growth factor (MGF) were higher in PH than in healthy controls, consistent with a doubling in cardiomyocyte cross-sectional area (CSA). Succinate dehydrogenase (SDH) activity was unaltered, indicating that oxidative capacity per cell increased. Although the Mb protein concentration was unchanged, Mb mRNA concentration was reduced. However, total RNA per nucleus was about threefold higher in PH rats versus controls, and Mb mRNA content expressed per nucleus was similar in the two groups. The increase in oxidative capacity without an increase in oxygen supply via Mb-facilitated diffusion caused a doubling of the critical extracellular oxygen tension required to prevent hypoxia (PO2crit). We conclude that Mb mRNA expression is not increased during pressure overload-induced right ventricular hypertrophy and that the increase in myoglobin content per myocyte is likely due to increased translation. We conclude that increasing Mb mRNA expression may be beneficial in the treatment of experimental PH.

Metabolic Modulation by Medium-Chain Triglycerides Reduces Oxidative Stress and Ameliorates CD36-Mediated Cardiac Remodeling in Spontaneously Hypertensive Rat in the Initial and Established Stages of Hypertrophy

BackgroundLeft ventricular hypertrophy (LVH) is characterized by a decrease in oxidation of long-chain fatty acids, possibly mediated by reduced expression of the cell-surface protein cluster of differentiation 36 (CD36). Spontaneously hypertensive rats (SHRs) were therefore supplemented with medium-chain triglycerides (MCT), a substrate that bypasses CD36, based on the assumption that the metabolic modulation will ameliorate ventricular remodeling. MethodsThe diet of 2-month-old and 6-month-old SHRs was supplemented with 5% MCT (Tricaprylin), for 4 months. Metabolic modulation was assessed by mRNA expression of peroxisome proliferator–activated receptor α and medium-chain acyl-CoA dehydrogenase. Blood pressure was measured noninvasively. LVH was assessed with the use of hypertrophy index, cardiomyocyte cross-sectional area, mRNA expression of B-type natriuretic peptide, cardiac fibrosis, and calcineurin-A levels. Oxidative stress indicators (cardiac malondialdehyde, protein carbonyl, and 3-nitrotyrosine levels), myocardial energy level (ATP, phosphocreatine), and lipid profile were determined. ResultsSupplementation of MCT stimulated fatty acid oxidation in animals of both age groups, reduced hypertrophy and oxidative stress along with the maintenance of energy level. Blood pressure, body weight, and lipid profile were unaffected by the treatment. ConclusionsThe results indicate that modulation of myocardial fatty acid metabolism by MCT prevents progressive cardiac remodeling in SHRs, possibly by maintenance of energy level and decrease in oxidative stress.