Atrial Natriuretic Peptide mRNA Expression Research Articles

Effects of pre-electroacupuncture on blood pressure and cardiac function in high-salt-induced hypertension rats

To observe the effects of pre-electroacupuncture at "Taichong"(LR3), "Neiguan"(PC6) and "Waiguan"(TE5) on blood pressure and cardiac function of high-salt-induced hypertension rats, so as to explore the possible mechanism of pre-electroacupuncture in improving hypertension. Twenty-four SD rats were randomly divided into control group, high-salt group and pre-electroacupuncture group, with 8 rats in each group. The hypertension model was established by feeding high-salt diet for 7 weeks. In the pre-electroacupuncture group, rats received electroacupuncture intervention at bilate-ral LR3, PC6 and TE5 (2 Hz/15 Hz, 2 mA) for 30 min, once a day, from the first day of modeling, for a total of 7 weeks. The blood pressure of rats was monitored by caudal artery noninvasive blood pressure measurement technique before and at the 1st, 3rd, 5th and 7th week of modeling. At the 8th week of the experiment, left ventricular catheterization was performed and biological signal acquisition system was used to detect left ventricular hemodynamics indexes and analyze left ventricular function, the car-diac mass ratio was measured to evaluate the degree of myocardial hypertrophy. The mRNA expressions of atrial natriuretic peptide(ANP), myosin heavy chain 7(MYH7), α-smooth muscle actin(α-SMA), interleukin(IL)-1β, and IL-6 of myocardial tissues were detected by quantitative real-time PCR. Sirius red staining was used to observe the degree of myocardial fibrosis. Compared with the control group, systolic blood pressure, diastolic blood pressure, mean arterial pressure, left ventricular end-diastolic pressure (LVEDP), cardiac mass ratio，and the mRNA expressions of ANP, MYH7, α-SMA, IL-1β, and IL-6, and sirius red staining area of myocardium were all significantly increased(P<0.01,P<0.05)，maximal rate of rise and descent of left ventricular pressure(LVP±dP/dtmax) were decreased (P<0.05,P<0.01) in the high-salt group. Compared with the high-salt group, rats in the pre-electroacupuncture group had lower systolic blood pressure, diastolic blood pressure, mean arterial pressure, LVEDP，cardiac mass ratio，higher LVP±dP/dtmax,down-regulated mRNA expressions of ANP, MYH7, α-SMA, IL-1β, IL-6, and smaller area of sirius red staining(P<0.05, P<0.01). Pre-electroacupuncture tends to lower blood pressure, improve cardiac function and reduce myocardial fibrosis in high-salt-induced hypertension rats, which may be associated with inhibiting inflammatory response.

Short-term Effects of Garlic-Based Diets on mRNA Expression of Angiotensinogen, Angiotensin-1 Converting Enzyme, and Atrial Natriuretic Peptide in Cyclosporine-Induced Prehypertensive Rats

The short-term effects of garlic, Allium sativum L., on the mRNA expression of angiotensin-1 converting enzyme (ACE), angiotensinogen (AGT), and atrial natriuretic peptide (ANP) in cyclosporine-induced prehypertensive rats were investigated in this work. Seven (7) groups of animals totaling n=7 were created. Prehypertensive (induced with 25mg/kg cyclosporine) and normal rats were given 10% and 20% diets based on garlic for 7 days. Alteration of Na+ and K+ levels, increased systolic and diastolic blood pressures, and ACE, AGT &amp; ANP mRNA expressions were all associated with cyclosporin-induced prehypertension. In rats placed on garlic-based diets, these effects were reversed.

Protective effects of calorie restriction and 17-β estradiol on cardiac hypertrophy in ovariectomized obese rats.

Obesity and menopause lead to cardiovascular diseases. Calorie restriction (CR) can modulate estrogen deficiency and obesity-related cardiovascular diseases. The protective effects of CR and estradiol on cardiac hypertrophy in ovariectomized obese rats were explored in this study. The adult female Wistar rats were divided into sham and ovariectomized (OVX) groups that received a high-fat diet (60% HFD) or standard diet (SD) or 30% CR for 16 weeks, and then, 1mg/kg E2 (17-β estradiol) was injected intraperitoneally every 4 days for four weeks in OVX-rats. Hemodynamic parameters were evaluated before and after each diet. Heart tissues were collected for biochemical, histological, and molecular analysis. HFD consumption led to weight gain in sham and OVX rats. In contrast, CR and E2 led to body weight loss in these animals. Also, heart weight (HW), heart weight/body weight (HW/BW) ratio, and left ventricular weight (LVW) were enhanced in OVX rats that received SD and HFD. E2 reduced these indexes in both diet conditions but reduction effects of CR were seen only in HFD groups. HFD and SD feeding increased hemodynamic parameters, ANP (atrial natriuretic peptide) mRNA expression, and TGF-β1(transforming growth factor-beta 1) protein level in the OVX animals, while CR and E2 reduced these factors. Cardiomyocyte diameter and hydroxyproline content were increased in the OVX-HFD groups. Nevertheless, CR and E2 decreased these indicators. The results showed that CR and E2 treatment reduced obesity-induced-cardiac hypertrophy in ovariectomized groups (20% and 24% respectively). CR appears to have almost as reducing effects as estrogen therapy on cardiac hypertrophy. The findings suggest that CR can be considered a therapeutic candidate for postmenopausal cardiovascular disease.

Dapagliflozin Ameliorates STZ-Induced Cardiac Hypertrophy in Type 2 Diabetic Rats by Inhibiting the Calpain-1 Expression and Nuclear Transfer of NF-κB.

Objective To investigate the effect of dapagliflozin (DAPA) on cardiac hypertrophy induced by type 2 diabetes mellitus (T2DM) and its mechanism. Methods SD rats with T2DM were divided into a T2DM group (n = 6) and DAPA group (n = 6). They were, respectively, fed with the same amount of normal saline and 1 mg/kg DAPA. The control group (n = 6) was also fed with normal saline. The hearts were tested by the application of echocardiography and hemodynamics. Subsequently, fasting blood glucose (FBG), serum total cholesterol (TC), and triglyceride (TG) as well as interleukin- (IL-) 10, IL-6, and tumor necrosis factor (TNF)-α in serum were tested. H&E and Masson staining was performed to observe the degree of cardiac tissue lesions, and expression of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), calpain-1, p-IκBα, and p65 in myocardial tissue was tested by qRT-PCR and Western blot. Results Compared with the control group, rats in the T2DM group exhibited significant diabetic symptoms: FBG was significantly elevated, and the levels of TC, TG, IL-6, and TNF-α were significantly increased, while the levels of IL-10 and the calpain activity were evidently decreased. However, DAPA treatment could improve the above changes. At the same time, the damage and fibrosis of the heart tissue in the DAPA group were markedly improved. Additionally, the mRNA expression of ANP and BNP in myocardial tissue of the DAPA group was markedly increased. And DAPA could inhibit the expression of p-IκBα/IκBα in the cytoplasm and p65 in the nucleus as well as the expression of calpain-1 in myocardial tissue. Conclusion DAPA treatment ameliorates the cardiac hypertrophy caused by T2DM by decreasing body blood glucose, while reducing the expression of calpain-1 in cardiomyocytes and inhibiting the nuclear translocation of NF-κB.

Difluoromethylornithine attenuates isoproterenol-induced cardiac hypertrophy by regulating apoptosis, autophagy and the mitochondria-associated membranes pathway.

Myocardial hypertrophy is an independent risk factor of cardiovascular diseases and is closely associated with the incidence of heart failure. In the present study, we hypothesized that difluoromethylornithine (DFMO) could attenuate cardiac hypertrophy through mitochondria-associated membranes (MAM) and autophagy. Cardiac hypertrophy was induced in male rats by intravenous administration of isoproterenol (ISO; 5 mg/kg/day) for 1, 3,7 and 14 days. For DFMO treatment group, rats were given ISO (5 mg/kg/day) for 14 days and 2% DFMO in their water for 4 weeks. The expression of atrial natriuretic peptide (ANP) mRNA,heart parameters, apoptosis rate, fibrotic area and protein expressions of cleaved caspase3/9, GRP75, Mfn2, CypD and VDAC1 were measured to confirm the development of cardiac hypertrophy, apoptosis and autophagy induced by ISO. ANP mRNA and MAM protein expression levels were assessed by reverse transcription-quantitative PCR and western blotting to evaluate hypertrophy and the effects of DFMO oral administration. The results demonstrated that heart parameters, ANP mRNA levels, fibrotic area and apoptosis rate were significantly increased in the heart tissue for ISO 7 and 14 day groups compared with the control group. Furthermore, treatment with DFMO significantly inhibited these indicators, and DFMO downregulated the MAM signaling pathway and upregulated the autophagy pathway in heart tissue compared with the ISO 14 day group. Overall, all ISO-induced changes analyzed in the present study were attenuated following treatment with DFMO. The findings form this study suggested that DFMO treatment may be considered as a potential strategy for preventing ISO-induced cardiac hypertrophy.

Protein kinase D participates in cardiomyocyte hypertrophy by regulating extracellular signal-regulated and myocyte enhancer factor 2D

ObjectiveCardiomyocyte hypertrophy is an important feature of hypertension. However, its molecular underpinnings, especially the signaling cascades, remain unclear. Here we hypothesized that a protein kinase D (PKD)-dependent extracellular signal-regulated kinase 5 (ERK5) pathway was able to regulate downstream myocyte enhancer factor 2D (MEF2D), affecting prohypertrophic responses to angiotensin II (Ang II). MethodsNeonatal rat cardiomyocytes from 2- to 3-day-old Sprague-Dawley rats were prepared and Western blot, real-time quantitative PCR and immunofluorescence staining were used to assess the activation and translocation of pathway signaling molecules. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) expression and [3H]-leucine (Leu) incorporation were measured to determine cell hypertrophy. ResultsElevated levels of phosphorylated PKD (p-PKD) and ERK5 (p-ERK5) were observed in cardiomyocytes stimulated with Ang II, while silencing protein kinase C epsilon (PKCɛ) resulted in significantly lower levels of p-PKD. Furthermore, Ang II-induced ERK5 activated translocation was mediated by the PKD pathway. Consequently, inhibiting PKCɛ, PKD and ERK5 by siRNA significantly attenuated Ang II-induced MEF2D activation, ANP and BNP mRNA expression, and [3H]-Leu incorporation. ConclusionsOur studies are the first to show that the PKCɛ/PKD/ERK5/MEF2D pathway plays an important role in the cardiomyocyte hypertrophy response to Ang II.

Effect of cardiac resynchronization therapy on left ventricular fibrosis-related mRNA expression profile in patients with end-stage heart failure

Abstract Background When indicated, cardiac resynchronization therapy (biventricular pacing, CRT) decreases mortality in patients with heart failure (HF) and reduced ejection fraction, especially in those with non-ischemic cardiomyopathy. This is reflected by relatively rapid improvement of left ventricular (LV) end-diastolic diameter (LVEDD) and LV ejection fraction (LVEF) indicating reverse remodelling. These LV structural and functional improvements are accompanied by characteristic changes in LV gene expression profile. However, whether beneficial gene expression alterations related to biventricular pacing are sustained independently of structural and functional reverse remodelling is unclear. Purpose We aimed to compare LV fibrosis-related mRNA expression profile in end-stage HF patients with idiopathic dilated cardiomyopathy (DCM) who were not on CRT versus to those on CRT. Methods Left ventricular myocardial samples were harvested from end-stage HF patients undergoing heart transplantation (HTX). Inclusion criteria were negative family history of DCM, negative coronarography (i.e. non-ischemic), no relevant comorbidity (e.g. diabetes, hypertension) and no history of myocarditis. Accordingly, the following patient groups were included: 1.) DCM (n=12, 17% female, mean age [±standard deviation] 46.8±11.8 years) without CRT and 2.) CRT-DCM (n=12, 42% female, mean age 47.8±12.3 years) which comprised DCM patients on active CRT for mean 3.2±2.4 years until HTX. LV RNA was extracted and subjected to a commercially available mRNA expression panel interrogating 760 genes related to the development and regulation of fibrosis. Normalization to 10 housekeeping genes and batch corrections were conducted as per protocol. LV mRNA expression of atrial-natriuretic peptide (ANP) was quantified using qRT-PCR. Results Markers of reverse remodelling including LVEDD (73.4±8.3 mm vs 75.4±9.9 mm), LVEF (21.9±3.7% vs 18.5±6.8%) and LV ANP mRNA expression (arbitrary units: 1.05±1.80 vs 1.04±0.88) were comparable between DCM and CRT-DCM patients (all P&amp;gt;0.05), respectively. High-throughput mRNA expression screening revealed significant (all P&amp;lt;0.001) downregulation of 3 genes proven to be implicated in adverse LV remodelling: alpha catalytic subunit of protein phosphatase 2 (PPP2CA), interleukin 20 receptor subunit beta (IL20RB) and lipoprotein lipase (LPL). According to pathway analysis using directed significance scores, CRT was associated with collective upregulation of genes modifying complement activation (SERPING1, C1S, CFH) and collective downregulation of genes promoting cell proliferation (PPP2CA, ANAPC7, HSP90AA1, CSNK2B). Conclusions Independently of structural and functional reverse remodelling, CRT might be associated with slightly favourable LV expression profile of genes related to the regulation and development of fibrosis. This suggests that biventricular pacing might be beneficial on the molecular level beyond improvement of LV structure and function. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary, Higher Education Institutional Excellence Programme of the Ministry of Human Capacities of Hungary

Atrial fibrillation is not associated with altered left atrial microRNA expression profile in ischemic end-stage human heart failure

Abstract Introduction In patients with chronic heart failure (CHF) left ventricular dysfunction results in elevated left atrial (LA) pressure, triggering pathological atrial remodelling and atrial fibrillation (AF). Nevertheless, it has been reported that some patients with CHF remain in sinus rhythm (SR) despite of the pathological structural alterations (e.g. dilation and fibrosis) of the LA. Of particular interest, data is scarce regarding the molecular explanation for the observed variability in AF development among CHF patients. Recent studies have indicated that alterations in microRNA (miRNA) expression might contribute to the pathogenesis of AF. However, the majority of previous studies focusing on miRNA expression compared healthy LA with SR to pathologically remodelled, dilated LA with AF. Consequently, whether dysregulation of miRNA expression directly contribute to AF and not only to pathological LA remodelling has not been tested before. Purpose The present study aimed to investigate miRNA expression in comparably remodelled LA from end-stage CHF patients with permanent AF (CHF-AF) or SR (CHF-SR). Methods LA samples were collected from male, non-diabetic, ischemic end-stage CHF patients undergoing heart transplantation (n=24). Patients were carefully selected to avoid any differences in age (55±2 vs. 54±2 years, CHF-AF vs. CHF-SR, n.s.), ejection fraction ([EF]: 22.5±1.8 vs. 23.3±2.5%, CHF-AF vs. CHF-SR, n.s.) LA diameters (longitudinal LA diameter: 56±4 vs. 48±5mm.; CHF-AF vs. CHF-SR, n.s.; horizontal LA diameter: 61±2 vs. 54±3, CHF-AF vs. CHF-SR, n.s.) and NYHA stage. As a molecular marker of atrial load, the mRNA expression of atrial natriuretic peptide (ANP) was measured with qRT-PCR. The extent of left atrial fibrosis was assessed on picrosirius red stained histological sections. Global LA miRNA expression profiling (including the measurement of 800 human miRNA) was carried out using a commercially available kit. Results LA mRNA expression of ANP was comparable between the AF-CHF and the SR-CHF groups, suggesting that atrial load occurred to the same level in the two experimental groups. Furthermore, no differences could be observed in the extent of atrial collagen content between the AF-CHF and the SR-CHF groups (collagen area: 20.3±1.3% vs. 23.9±3.1%, n.s.), providing evidence that fibrotic remodelling had occurred to a similar magnitude. The high-throughput miRNA measurement revealed no differences in atrial miRNA expression between the two study groups. Conclusion The present study provides evidence for the first time that AF is not associated with different LA miRNA expression in end-stage CHF patients with comparable level of LA dilatation, ANP expression (atrial load) and interstitial fibrosis. Based on these findings, the potential of miRNA-based therapeutic interventions might be limited in AF patients with ischemic end-stage CHF. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): NVKP_16-1-2016-0017

Effects of Sirt3‑autophagy and resveratrol activation on myocardial hypertrophy and energy metabolism.

The aim of the present study was to examine the role of sirtuin 3 (Sirt3)-autophagy in regulating myocardial energy metabolism and inhibiting myocardial hypertrophy in angiotensin (Ang) II-induced myocardial cell hypertrophy. The primary cultured myocardial cells of neonatal Sprague Dawley rats were used to construct a myocardial hypertrophy model induced with Ang II. Following the activation of Sirt3 by resveratrol (Res), Sirt3 was silenced using small interfering (si)RNA-Sirt3, and the morphology of the myocardial cells was observed under an optical microscope. Reverse transcription-polymerase chain reaction was used to detect the mRNA expression of the following myocardial hypertrophy markers; atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), Sirt3, medium-chain acyl-CoA dehydrogenase (MCAD) and pyruvate kinase (PK). Western blot analysis was used to detect the protein expression of Sirt3, light chain 3 (LC3) and Beclin1. Ang II may inhibit the protein expression of Sirt3, LC3 and Beclin1. Res, an agonist of Sirt3, may promote the protein expression of Sirt3, LC3 and Beclin1. Res inhibited the mRNA expression of ANP and BNP, and reversed the Ang II-induced myocardial cell hypertrophy. The addition of siRNA-Sirt3 decreased the protein expression of Sirt3, LC3 and Beclin1, increased the mRNA expression of ANP and BNP, and weakened the inhibitory effect of Res on myocardial cell hypertrophy. Res promoted the mRNA expression of MCAD, inhibited the mRNA expression of PK, and reversed the influence of Ang II on myocardial energy metabolism. siRNA-Sirt3 intervention significantly decreased the effect of Res in eliminating abnormal myocardial energy metabolism. In conclusion, Sirt3 may inhibit Ang II-induced myocardial hypertrophy and reverse the Ang II-caused abnormal myocardial energy metabolism through activation of autophagy.

Taurine prevents cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers

The calpain-1-activated apoptotic pathway plays a key role in right ventricular hypertrophy (RVH). Taurine has been shown to attenuate apoptosis by inhibiting calpain activity. This experiment aimed to determine whether taurine could prevent RVH by inhibiting the calpain-1/cytochrome c apoptotic pathway. The broilers were given 1% taurine dissolved in drinking water and were raised at 10°C ~ 12°C from day 21 to day 42. At 21 d, 28 d, 35 d and 42 d, the right ventricular (RV) tissues were collected. Increased RVH index, angiotensin II, norepinephrine and atrial natriuretic peptide mRNA expression were reduced by taurine in the broiler RVs. Taurine obviously inhibited cardiomyocyte apoptosis via maintaining the mitochondrial membrane potential and decreased the activation of caspase-9 and caspase-3 in the broiler RVs. The antioxidant assay demonstrated that taurine enhanced the activities of superoxide dismutase, total antioxidant capacity and glutathione peroxidase and the glutathione/glutathione disulfide ratio. Western blot results revealed that taurine also downregulated the expression of calpain-1 and cytosolic cytochrome c while upregulating the expression of Bcl-2/Bax and mitochondrial cytochrome c in broiler cardiomyocytes during RVH. In summary, we found that taurine could enhance cardiomyocyte antioxidant ability and further prevented cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers.

Dendrobium candidum aqueous extract attenuates isoproterenol-induced cardiac hypertrophy through the ERK signalling pathway

Context The pharmacological functions of Dendrobium candidum Wall. ex Lindl. (Orchidaceae) in cardiac hypertrophy remains unclear. Objective To evaluate whether D. candidum aqueous extract (DCAE) can attenuate experimental cardiac hypertrophy. Materials and methods Cardiac hypertrophy in SD rats was induced by subcutaneously injection of isoproterenol (2 mg/kg), once a day for ten days. Rats were gavaged with DCAE (0.13 and 0.78 g/kg) daily for one month. At the end of treatment, measurement of left ventricular systolic pressure (LVSP), heart-to-body weight ratio (HW/BW), left ventricular/tibia length (LV/TL), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) levels, haematoxylin-eosin staining, and Masson’s trichrome staining were conducted. In cultured H9c2 cells, DCAE (2 mg/mL) and U0126 (10 μM) were added 2 h before the isoproterenol (10 μM) stimulus. Phalloidin staining was used to evaluate cellular hypertrophy. The mRNA expression of ANP and BNP was measured by qRT-PCR. The expression of p-ERK was determined by immunoblotting. Results DCAE treatment significantly reduced the following indicators in vivo: (1) the LVSP (16%); (2) HW/BW (13%); (3) LV/TL (6%); (4) ANP (39%); (5) BNP (32%). In cultured H9c2 cells, phalloidin staining showed that DCAE relieved cellular hypertrophy (53% reduction). Furthermore, immunoblotting showed that DCAE can significantly inhibit p-ERK protein expression in vivo and in vitro (39% and 27% reduction, respectively). Discussion and conclusions DCAE prevents cardiac hypertrophy via ERK signalling pathway and has the potential for treatment of cardiac hypertrophy.

Antisense regulation of atrial natriuretic peptide expression.

The cardiac hormone atrial natriuretic peptide (ANP) is a central regulator of blood volume and a therapeutic target in hypertension and heart failure. Enhanced ANP activity in such conditions through inhibition of the degradative enzyme neprilysin has shown clinical efficacy but is complicated by consequences of simultaneous accumulation of a heterogeneous array of other hormones. Targets for specific ANP enhancement have not been available. Here, we describe a cis-acting antisense transcript (NPPA-AS1), which negatively regulates ANP expression in human cardiomyocytes. We show that NPPA-AS1 regulates ANP expression via facilitating NPPA repressor RE1-silencing transcription factor (REST) binding to its promoter, rather than forming an RNA duplex with ANP mRNA. Expression of ANP mRNA and NPPA-AS1 was increased and correlated in isolated strained human cardiomyocytes and in hearts from patients with advanced heart failure. Further, inhibition of NPPA-AS1 in vitro and in vivo resulted in increased myocardial expression of ANP, increased circulating ANP, increased renal cGMP, and lower blood pressure. The effects of NPPA-AS1 inhibition on NPPA expression in human cardiomyocytes were further marked under cell-strain conditions. Collectively, these results implicate the antisense transcript NPPA-AS1 as part of a physiologic self-regulatory ANP circuit and a viable target for specific ANP augmentation.

ANP-stimulated Na+ secretion in the collecting duct prevents Na+ retention in the renal adaptation to acid load.

We have recently reported that type A intercalated cells of the collecting duct secrete Na+ by a mechanism coupling the basolateral type 1 Na+-K+-2Cl- cotransporter with apical type 2 H+-K+-ATPase (HKA2) functioning under its Na+/K+ exchange mode. The first aim of the present study was to evaluate whether this secretory pathway is a target of atrial natriuretic peptide (ANP). Despite hyperaldosteronemia, metabolic acidosis is not associated with Na+ retention. The second aim of the present study was to evaluate whether ANP-induced stimulation of Na+ secretion by type A intercalated cells might account for mineralocorticoid escape during metabolic acidosis. In Xenopus oocytes expressing HKA2, cGMP, the second messenger of ANP, increased the membrane expression, activity, and Na+-transporting rate of HKA2. Feeding mice with a NH4Cl-enriched diet increased urinary excretion of aldosterone and induced a transient Na+ retention that reversed within 3 days. At that time, expression of ANP mRNA in the collecting duct and urinary excretion of cGMP were increased. Reversion of Na+ retention was prevented by treatment with an inhibitor of ANP receptors and was absent in HKA2-null mice. In conclusion, paracrine stimulation of HKA2 by ANP is responsible for the escape of the Na+-retaining effect of aldosterone during metabolic acidosis.

Paeo‐tang attenuates disharmony between the heart and kidney in L‐NAME‐induced hypertension

Hypertension has been approved to cause disharmony between the heart and kidney such as cardiac hypertrophy and kidney dysfunction. In traditional oriental medicine Paeo‐tang (PET) has been shown to have effects on blood circulation improvement. However, the beneficial effect of PET on hypertension remains unknown. In this study, we investigated that PET attenuates blood pressure and suppresses cardiac hypertrophy in NG‐nitro‐L‐arginine methylester (L‐NAME) rat model. Hypertensive rat models were induced by the administration of L‐NAME (40 mg/kg/day) and then PET (50 or 100 mg/kg/day) or Olmetec was treated for 2 weeks. PET treatment significantly suppressed the systolic blood pressure and decreased intima‐media thickness in the thoracic aorta. PET restored the L‐NAME‐induced decrease in aortic relaxation response to acetylcholine and atrial natriuretic peptide (ANP). However, PET didn't restore the aortic relaxation response to sodium nitroprusside. PET markedly restored the phosphorylation of endothelial nitric oxide synthase in aortic tissue. Heart weight and ANP mRNA expression in heart tissue were decreased by PET in a dose‐dependent manner. PET ameliorated the functional decline in the kidney such as albumin, blood urea nitrogen, creatinine. These results demonstrated that PET possesses vascular protective effects against L‐NAME‐induced hypertension. In addition, PET regulates harmony between the heart and kidney via inhibition of cardiac hypertrophy and renal dysfunction.Support or Funding InformationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Simvastatin Improves Cardiac Hypertrophy in Diabetic Rats by Attenuation of Oxidative Stress and Inflammation Induced by Calpain-1-Mediated Activation of Nuclear Factor-κB (NF-κB).

BackgroundSimvastatin, an HMG-CoA reductase inhibitor, has been reported to exert multiple protective effects on the cardiovascular system. However, the molecular mechanism remains to be examined. The present study was designed to study the effects of simvastatin on cardiac hypertrophy in diabetic rats and to explore its potential mechanism.Material/MethodsSprague-Dawley rats were assigned into a control (Con) group, a streptozotocin (STZ) group, and a STZ+simvastatin (STZ+SIM) group. The level of reactive oxygen species (ROS) was measured by using dihydroethidium (DHE) staining. The protein expressions of p65, IκBα, vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), calpain-1, and endothelial nitric oxide synthase (eNOS) were examined by Western blot analysis. qPCR was used to detect the levels of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP).ResultsSimvastatin improved the cardiac hypertrophy of diabetic rats, as demonstrated by decreases in the ratios of left ventricular weight/body weight (LVW/BW) and heart weight/body weight (HW/BW) and by the downregulation of mRNA expression of BNP and ANP in the heart tissue. Simvastatin decreased the protein expressions of VCAM-1, ICAM-1, IL-6, and TNF-α, increased eNOS protein expression, and limited an increase in ROS levels in the heart tissue. Simvastatin increased IκBα protein expression in cytoplasm and inhibited the translocation of p65, the subunit of nuclear factor-κB (NF-κB) to the nucleus from the cytoplasm of the heart tissue. Furthermore, simvastatin attenuated the activity of calpain and calpain-1 protein expression in heart tissue.ConclusionsSimvastatin attenuates cardiac hypertrophy in diabetic rats, which might be due to the attenuation of oxidative stress and inflammation induced by calpain-1-mediated activation of NF-κB.

Modification of gene expression in rat cardiomyocytes by linoleic and docosahexaenoic acids 1.

Regulation of cardiac fatty acid metabolism is central to the development of cardiac hypertrophy and heart failure. We investigated the effects of select fatty acids on the expression of genes involved in immediate early as well as inflammatory and hypertrophic responses in adult rat cardiomyocytes. Cardiac remodeling begins with upregulation of immediate early genes for c-fos and c-jun, followed by upregulation of inflammatory genes for nuclear factor kappa B (NF-κB) and nuclear factor of activated T-cells (NFAT). At later stages, genes involved in hypertrophic responses, such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), are upregulated. Adult rat cardiomyocytes were treated with palmitic acid, a saturated fatty acid; oleic acid, a monounsaturated fatty acid; linoleic acid, a polyunsaturated fatty acid belonging to the n-6 class; and docosahexaenoic acid, a polyunsaturated fatty acid belonging to the n-3 class. Linoleic acid produced a greater increase in the mRNA expression of c-fos, c-jun, NF-κB, NFAT3, ANP, and BNP relative to palmitic acid and oleic acid. In contrast, docosahexaenoic acid caused a decrease in the expression of genes involved in cardiac hypertrophy. Our findings suggest that linoleic acid may be a potent inducer of genes involved in cardiac hypertrophy, whereas docosahexaenoic acid may be protective against the cardiomyocyte hypertrophic response.

Atrial secretion of ANP is suppressed in renovascular hypertension: shifting of ANP secretion from atria to the left ventricle.

In the present study, the change in secretion of atrial natriuretic peptide (ANP) from the atria was defined in hypertension accompanied by ventricular hypertrophy and increased synthesis of ANP. To identify the change of the secretion and mechanisms involved, experiments were performed in isolated perfused beating atria from sham-operated normotensive and renovascular hypertensive rats. Expression of ANP, natriuretic peptide receptor (NPR)-C, components of the renin-angiotensin system, and muscarinic signaling pathway was measured in cardiac tissues. Basal levels of ANP secretion and acetylcholine (ACh)- and stretch-induced activation of ANP secretion were suppressed in the atria from hypertensive compared with normotensive rats. ACh increased ANP secretion via M2 muscarinic ACh receptor-ACh-sensitive K+ channel signaling. In hypertensive rats, ANP concentration increased in the left ventricle but decreased in the right ventricle. The atrial concentration of ANP was not changed in hypertensive compared with normotensive rats. ANP mRNA expression was accentuated in the left ventricle but suppressed in the other cardiac chambers in the hearts of hypertensive rats. NPR-C expression was inversely related to ANP mRNA levels. Angiotensin II type 1 receptor (AT1R) expression was accentuated in the cardiac chambers from hypertensive rats compared with normotensive rats, whereas angiotensin II type 2 receptor, M2 muscarinic receptor, and Kir3.4 channels were suppressed. AT1R blockade with losartan reversed the change observed in hypertensive rats. The present findings indicate that renovascular hypertension shifts the major site of ANP secretion and synthesis from the atria to the left ventricle through modulation of the expression of ANP, NPR-C, AT1R, and the M2 muscarinic signaling pathway. NEW & NOTEWORTHY Renovascular hypertension suppresses the atrial secretion of ANP and shifts the major site of the regulation of ANP secretion and synthesis from atria to the hypertrophied left ventricle possibly via modulation of the expression of ANP, natriuretic peptide receptor-C, angiotensin II subtype 1 receptor, and M2 muscarinic signaling pathway.

AMPK regulates energy metabolism through the SIRT1 signaling pathway to improve myocardial hypertrophy.

We investigated the correlations of adenosine monophosphate-activated protein kinase (AMPK), Silence information regulator 1 (SIRT1) and energy metabolism with myocardial hypertrophy. Myocardial hypertrophy experimental model was established via transverse aortic constriction (TAC)-induced myocardial hypertrophy and phenylephrine (PE)-induced hypertrophic myocardial cell culture. After activation of AMPK, the messenger ribonucleic acid (mRNA) expressions in myocardial tissue- and myocardial cell hypertrophy-related genes, atrial natriuretic peptide (ANP) and β-myosin heavy chain (β-MHC), were detected. The production rate of 14C-labeled 14CO2 from palmitic acid was quantitatively determined to detect the fatty acid and glucose oxidation of hypertrophic myocardial tissues or cells, and the glucose uptake of myocardial cells was studied using [14C] glucose. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to detect the changes in SIRT1 mRNA and protein expressions in hypertrophic myocardial tissues. Moreover, SIRT1 small interfering ribonucleic acid (siRNA) was used to interfere in SIRT1 expression to further investigate the role of SIRT1 in the effect of AMPK activation on myocardial hypertrophy. AMPK activation could significantly reduce the mRNA expressions of ANP and β-MHC in vitro and in vivo. AMPK could increase the ejection fraction (EF) and decrease the protein synthesis rate in myocardial cells in mice with myocardial hypertrophy. Besides, AMPK activation could increase the fatty acid oxidation, improve the glucose uptake and reduce the glucose oxidation. After AMPK activation, both SIRT1 mRNA and protein expressions in hypertrophic myocardial tissues and myocardial cells were increased. After SIRT1 siRNA was further used to interfere in SIRT1 expression in myocardial cells, it was found that mRNA expressions and protein synthesis rates of ANP and β-MHC were increased. The activation of AMPK can inhibit the myocardial hypertrophy, which may be realized through regulating the myocardial energy metabolism via SIRT1 signaling pathway.

Effect of acupuncture on the genetic expression of myocardial endothelin-1 and atrial natriuretic peptide in rats with stress-induced prehypertension

ObjectiveTo explore the protective effect of acupuncture against myocardial injury in rats with stress-induced prehypertension (SIPH) by observing the genetic expression of myocardial endothelin-1 (ET-1) and atrial natriuretic peptide (ANP). MethodsThirty-six Wistar rats were randomized into three groups: the control group, model group, and model + acupuncture (AP) group (n = 12 rats per group). During the 11-day modeling period, the model group and the model + AP group experienced plantar electric stimulation in combination with noise exposure, and daily acupuncture intervention was applied simultaneously in the model + AP group; the control group did not experience modeling or acupuncture. Systolic pressure (SP) was measured the day before modeling began, and on the 3rd, 5th, 7th, 9th, and 11th day after modeling initiation. On the 12th day, histopathological observation of the left ventricle was made with hematoxylin-eosin staining and quantitative genetic expression of myocardial ET-1, and ANP was tested by quantitative real-time polymerase chain reaction (PCR). ResultsSP was higher in the model group than the control group on the 3rd, 5th, 7th, 9th, and 11th days (all P < .01). SP in the model + AP group was lower than that in the control group on the 5th and 7th days (respectively, P = .008, P = .002) and on the 9th and 11th days (P = .029, P = .039). Hematoxylin-eosin staining showed normal myocardial cellular structure in the control group. The model group showed disordered arrangement of cardiac cells with morphological changes in some nuclei, including enlargement or dissolution; there was also infiltration of inflammatory cells and proliferation of collagen fibers. In the model + AP group, most of the myocardial cells were normally structured, and only part of the cells had morphological changes with enlarged nuclei or dissolution. Real-time PCR showed that expression of ET-1 and ANP mRNA in the model group was greater than the control group (respectively, P = .024, P = .000101). The model + AP group had lower expression of ET-1 and ANP mRNA compared with the model group (respectively, P = .033, P = .043). ConclusionAcupuncture may lower blood pressure and downregulate the genetic expression of myocardial ET-1 and ANP in SIPH rats, suggesting a protective effect of acupuncture against myocardial damage.

Cyclin-Dependent Kinase Inhibitor p21WAF1/CIP1 Facilitates the Development of Cardiac Hypertrophy

Background/Aims: Adult cardiomyocytes can re-enter cell cycle as stimulated by prohypertrophic factors although they withdraw from cell cycle soon after birth. p21WAF1/CIP1, a cyclin-dependent kinase inhibitor, has been implicated in cardiac hypertrophy, however, its precise contribution to this process remains largely unclear. Methods: The gene expression profile in left ventricle (LV) of spontaneously hypertensive rats (SHR) and Wistar–Kyoto (WKY) rats was determined using quantitative PCR array and verified by real-time PCR and Western blotting. Hypertrophic response of H9c2 cells and neonatal rat ventricular myocytes (NRVM) were induced by angiotensin II (1 µmol/L). Cardiac hypertrophy of mice was elicited by isoproterenol (ISO) infusion (40 mg/kg per day for 14 days). p21-adenovirus and p21-siRNA were employed to transfect NRVM, and sterigmatocystin (STE, 3 mg/kg, ip, qd) was used to inhibit p21 activity. mRNA and protein expression levels of α- and β-myosin heavy chain (MHC), p21WAF1/CIP1, calcineurin (CaN) and atrial natriuretic peptide (ANP) were assayed by realtime PCR and WB, respectively. Results: Sixteen genes showed two-fold or greater changes between SHR and WKY rats, in which the expression of p21WAF1/CIP1 was upregulated by 4.15-fold (P=0.002) and reversed by losartan. Surface area, protein content, mRNA and protein expressions of β-MHC, ANP and p21WAF1/CIP1 in H9c2 cells treated with AngII elevated significantly compared with control group. p21-Ad transfection markedly increased the surface area and β-MHC mRNA expression of normal NRVMs, and p21-siRNA transfection decreased them in AngII-treated NRVMs. STE treatment decreased HW/BW and cross-sectional area, expression levels of β-MHC, ANP and p21 significantly in ISO-treated mice. Conclusion: Our findings suggest that p21 facilitates the development of cardiac hypertrophy, and regulating the expression of p21 may be an approach to attenuate hypertrophic growth of cardiomyocytes.