Injection Of Monocrotaline Research Articles

Astragaloside IV blocks monocrotaline‑inducedpulmonary arterial hypertension by improving inflammation and pulmonary artery remodeling.

Pulmonary arterial hypertension (PAH) is associated with increased inflammation and abnormal vascular remodeling. Astragaloside IV (ASIV), a purified small molecular saponin contained in the well-know herb, Astragalus membranaceus, is known to exert anti-inflammatory and anti-proliferation effects. Thus, the present study investigated the possible therapeutic effects of ASIV on monocrotaline (MCT)-induced PAH. Rats were administered a single intraperitoneal injection of MCT (60 mg/kg), followed by treatment with ASIV at doses of 10 and 30 mg/kg once daily for 21 days. Subsequently, right ventricle systolic pressure, right ventricular hypertrophy and serum inflammatory cytokines, as well as pathological changes of the pulmonary arteries, were examined. The effects of ASIV on the hypoxia-induced proliferation and apoptotic resistance of human pulmonary artery smooth muscle cells (HPASMCs) and the dysfunction of human pulmonary artery endothelial cells (HPAECs) were evaluated. MCT elevated pulmonary artery pressure and promoted pulmonary artery structural remodeling and right ventricular hypertrophy in the rats, which were all attenuated by both doses of ASIV used. Additionally, ASIV prevented the increase in the TNF-α and IL-1β concentrations in serum, as well as their gene expression in lung tissues induced by MCT. In in vitro experiments, ASIV attenuated the hypoxia-induced proliferation and apoptotic resistance of HPASMCs. In addition, ASIV upregulated the protein expression of p27, p21, Bax, caspase-9 and caspase-3, whereas it downregulated HIF-1α, phospho-ERK and Bcl-2 protein expression in HPASMCs. Furthermore, in HPAECs, ASIV normalized the increased release of inflammatory cytokines and the increased protein levels of HIF-1α and VEGF induced by hypoxia. On the whole, these results indicate that ASIV attenuates MCT-induced PAH by improving inflammation, pulmonary artery endothelial cell dysfunction, pulmonary artery smooth muscle cell proliferation and resistance to apoptosis.

BKCa Channel Activation Attenuates the Pathophysiological Progression of Monocrotaline-Induced Pulmonary Arterial Hypertension in Wistar Rats.

In the present study, the therapeutic efficacy of a selective BKCa channel opener (compound X) in the treatment of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) was investigated. PAH was induced in male Wistar rats by a single injection of MCT. After two weeks, the MCT-treated group was divided into two groups that were either treated with compound X or vehicle. Compound X was administered daily at 28mg/kg. Electrocardiographic, echocardiographic, and haemodynamic analyses were performed; ex vivo evaluations of pulmonary artery reactivity, right ventricle (RV) and lung histology as well as expression levels of α and β myosin heavy chain, brain natriuretic peptide, and cytokines (TNFα and IL10) in heart tissue were performed. Pulmonary artery rings of the PAH group showed a lower vasodilatation response to acetylcholine, suggesting endothelial dysfunction. Compound X promoted strong vasodilation in pulmonary artery rings of both control and MCT-induced PAH rats. The untreated hypertensive rats presented remodelling of pulmonary arterioles associated with increased resistance to pulmonary flow; increased systolic pressure, hypertrophy and fibrosis of the RV; prolongation of the QT and Tpeak-Tend intervals (evaluated during electrocardiogram); increased lung and liver weights; and autonomic imbalance with predominance of sympathetic activity. On the other hand, treatment with compound X reduced pulmonary vascular remodelling, pulmonary flow resistance and RV hypertrophy and afterload. The use of a selective and potent opener to activate the BKCa channels promoted improvement of haemodynamic parameters and consequent prevention of RV maladaptive remodelling in rats with MCT-induced PAH.

Abstract 16849: Extracellular Vesicles Derived From Mesenchymal Stem Cells Protects Mice From Monocrotaline-Induced Pulmonary Hypertension and Improve Echocardiographic Parameters

Introduction: Pulmonary hypertension (PH) is a currently incurable disease with high morbidity and mortality. Treatment with extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) appeared to be effective and promising. Objective: We aimed at evaluating whether MSC-EVs could improve right ventricle (RV) and pulmonary artery (PA) functions in mice with PAH induced by monocrotaline (MCT). Methods: FVB mice (M/F – 6 weeks) received MCT injections 1x/week for 4 weeks (60mg/kg sc.) and were treated with MSCs-EVs 24 hours after each MCT injection (3x10 6 cells in 100μL PBS 1x, iv.). The experimental groups were: Control (vehicle-vehicle; n=9); MCT (MCT-vehicle; n=10); Control EVs (vehicle-EVs; n=8); MCT EVs (MCT-EVs; n=10); PA acceleration time (PAT), PA ejection time (PET) and tricuspid annular plane systolic excursion (TAPSE) were assessed by echocardiography 28 days after first MCT injection; Fulton index was used to calculate RV hypertrophy, and pulmonary vascular remodeling (WT/D) was assessed by histology. Results: PAT and PAT/PET were decreased by 22.6±5.7% and 15.6±4.9%, respectively, in MCT group compared to Control (p<0.01 and p<0.02). PAT was increased in Control EVs and MCT EVs groups when compared with MCT group (by 28.2±7.6%, p<0.01 and 20±6.9%, p<0.04, respectively). TAPSE (figure 1) was decreased in the MCT group compared with Control (42.9±6.7%, p<0.0001) and increased in both Control EVs (62.8±12.2%, p<0.0001) and MCT EVs (52.7±11.1%, p<0.0005) groups compared with MCT group. In addition, MCT group presented RV hypertrophy 49.4±16.5% higher than Control (p<0.03), and 29.1±10.4% higher than MCT EVs group (p<0.05). The WT/D was increased in MCT compared to Control (63.7±7.6%, p<0.0001), but decreased in Control EVs (44.9±4.6%, p<0.0001) and MCT EVs (44.3±5.4%, p<0.0001) in relation to MCT group. Conclusion: Treatment with MSC-EVs protects against the development of PH and improves PA and the RV function in MCT-treated mice.

Abstract 13527: Inhibition of With-No-Lysine Kinase Improves Right Ventricular Function by Blunting Excess Protein O-GlcNAcylation

Introduction: Pulmonary arterial hypertension (PAH) is caused by obstructive remodeling of the pulmonary arteries which ultimately causes right ventricle (RV) failure and death. Increased expression of the glucose membrane transporters Glut1 and Glut4 occurs in the failing RV, but the upstream regulators of these proteins are unknown. The With-no-Lysine (WNK) kinase-1, a kinase activated in low chloride conditions, promotes expression of Glut1/4 in skeletal muscle, but its regulation in the RV in PAH is unexplored. Furthermore, the relationship between WNK1 and protein O-GlcNAcylation, a glucose based post-translational modification, has not been examined. Methods: Immunoblots quantified the abundance of WNK1, Glut1, Glut4, and total protein O-GlcNAcylation in the RV of control, monocrotaline (MCT) rats, and MCT rats treated with a WNK inhibitor two weeks after MCT injection. Echocardiography and pressure-volume loop analysis assessed RV function and pulmonary vascular disease severity. Results: Treatment with WNK inhibitor improved TAPSE (2.4±0.1 vs 1.8±0.1 mm, p =0.0007), cardiac output (86.0±9.1 vs 52.5±5.6 ml/min, p =0.02), and cardiac output normalized body weight (0.26±0.03 vs 0.15±0.02 ml/min/g, p =0.0032). Importantly, the WNK inhibitor did not alter pulmonary vascular disease severity as there were no differences in pulmonary artery acceleration time (18.2±1.5 vs 14.2±0.9 sec, p =0.22), Ea (0.58±0.07 vs 0.58±0.08 mmHg/μL, p=1.00), or right ventricular systolic pressure (71.8±7.6 vs 72.0±4.0 mmHg, p =1.00) compared to MCT. At the molecular level, WNK1 inhibition decreased expression of WNK1 (MCT: 1.3±0.2 fold increase, MCT-WNK: 3.4±2.2 fold decrease), Glut1 (MCT: 2.7±0.9 fold increase, MCT-WNK: 1.2±0.2 fold increase), Glut4 (MCT: 1.7±0.4 fold increase, MCT-WNK: 1.0±0.2 fold increase), and protein O-GlcNAcylation (MCT: 2.4±0.7 fold increase, MCT-WNK: 1.1±0.1 fold increase). Conclusions: WNK inhibition normalized Glut1/4 expression and protein O-GlcNAcylation in the RV. These molecular changes resulted in improved RV function without a change in pulmonary vascular disease burden.

Abstract 13715: Pathophysiological Role of Dexmedetomidine for Monocrotaline-induced Pulmonary Arterial Hypertension in Rats

Introduction: The abnormal proliferation of pulmonary arterial smooth muscle cells (PASMCs) is one of pathological characteristics of pulmonary arterial hypertension (PAH). Inflammation is thought to play an important role for PASMCs proliferation in PAH. Dexmedetomidine (DEX) is a selective α2-adrenergic receptor agonist that is used as a sedative in clinical settings. It has been reported that DEX regulates certain inflammatory responses. Hypothesis: DEX ameliorates Monocrotaline (MCT)-induced PAH in rats through its anti-inflammatory effect. Methods: In vivo, 6-week-old male Sprague-Dawley rats were injected 60 mg/kg of MCT subcutaneously. At day 14 after MCT injection, continuous infusions of DEX (2μg/kg/hour) by osmotic pumps were started in one group (MCT + DEX group), and not in another group (MCT group). We performed cardiac catheterization to measure right ventricular systolic pressure (RVSP) and prepared rats paraffin embedded lung tissues for Immunohistochemistry at day 23. In vitro, we analyzed the effect of DEX on human PASMCs (hPASMCs) proliferation stimulated with fibroblast growth factor 2 (FGF2). In addition, we examined mRNA levels of proinflammatory cytokines in hPASMCs by FGF2 stimuation with/without DEX. Results: Both RVSP and survival rate markedly improved in MCT + DEX group compared with those in MCT group (RVSP; 34mmHg ± 4mmHg vs. 70mmHg ± 10mmHg, survival rate 42% vs. 0% at day 29). In histological analysis, medial hypertrophy of pulmonary arterioles and phosphorylated-p65 positive PASMCs significantly reduced in MCT + DEX group. DEX also inhibited hPASMCs proliferation dose dependently. Furthermore, IL-6 mRNA expression was suppressed by DEX in hPASMCs stimulated with FGF2. Conclusions: DEX improved MCT-induced PAH in rats by suppressing PASMCs proliferation through the anti-inflammatory effect, which may result from inhibition of NF-κB activation induced by IL-6. DEX can be a new therapeutic tool for PAH.

Metformin prevents the development of monocrotaline-induced pulmonary hypertension by decreasing serum levels of big endothelin-1.

Pulmonary hypertension (PH) is a disease with poor prognosis, and it is characterized by the progressive elevation of pulmonary vascular resistance and pressure. Various factors are associated with the pathology of PH, including AMP-activated protein kinase (AMPK) deficiency. The present study aimed to evaluate the therapeutic effect of metformin, an AMPK activator, in a monocrotaline (MCT)-induced PH rat model. Rats were randomly divided into the following three groups: i) Saline-injected group (sham group); ii) monocrotaline (MCT)-injected group (PH group); iii) MCT-injected and metformin-treated group (MT group). Four weeks following MCT injection, cardiac ultrasonography, invasive hemodynamic measurements, measurement of serum levels of big endothelin-1 (big ET-1) and histological analysis were performed to evaluate the effect of metformin treatment in PH. Pulmonary arterial pressure and serum big ET-1 concentrations were reduced in the MT group compared with the PH group. Medial wall thickness and wall area of the pulmonary arterioles in the MT group were decreased compared with the PH group. Comparing the right heart functional parameters among groups revealed that the acceleration time/ejection time ratio improved in the MT group compared with the PH group. Thus, the present study demonstrated the efficacy of metformin in an MCT-induced PH rat model and suggested that metformin may be a valuable, potential novel therapeutic for the treatment of PH.

DDCI-01, a novel long acting phospdiesterase-5 inhibitor, attenuated monocrotaline-induced pulmonary hypertension in rats.

Pulmonary arterial hypertension is a progressive, malignant heart disease, characterized by pulmonary arteriole remodeling and increased pulmonary vascular resistance, which eventually leads to right heart failure. This study sought to evaluate the effects of a novel long-acting phospdiesterase-5 inhibitor, namely DDCI-01, as an early intervention for monocrotaline-induced pulmonary hypertensive rats. To establish this model, 50 mg/kg of monocrotaline was intraperitoneally injected into rats. At Day 7 after monocrotaline injection, two doses of DDCI-01 (3 or 9 mg/kg/day) or tadalafil (at 3 or 9 mg/kg/day) were intragastrically administered. The rats were anesthetized with pentobarbital for hemodynamic and echocardiographic measurements, at Day 21 after monocrotaline injection. Compared to the monocrotaline group, DDCI-01 at 3 and 9 mg/kg/day (P) reduced the mean pulmonary arterial pressure (mPAP), right ventricular systolic pressure, right ventricular transverse diameter, pulmonary arterial medial wall thickness (WT%), and right ventricle hypertrophy. However, no significant difference in the indices mentioned as above was found between DDCI-01 (3 mg/kg/day) and tadalafil (3 mg/kg/day). In addition, DDCI-01 at 9 mg/kg/day resulted in lower mPAP and WT%, as well as higher cyclic guanosine monophosphate levels in the lung and plasma compared with the same dose of tadalafil (9 mg/kg/day) (all P < 0.05). These findings suggested that DDCI-01 improved monocrotaline-induced pulmonary hypertension in rats, and a dose of DDCI-01 of 9 mg/kg/day might be more effective than the same dose of tadalafil in monocrotaline-induced pulmonary hypertension in rats.

Plexiform Lesions in an Experimental Model of Monocrotalin-Induced Pulmonary Arterial Hypertension.

ResumoFundamento O modelo de hipertensão arterial pulmonar induzida por monocrotalina (MCT) é um dos mais reproduzidos atualmente, apresentando como limitação a ausência de lesões plexiformes, manifestações típicas da doença grave em humanos.Objetivo Avaliar a gravidade da arteriopatia pulmonar induzida por MCT por meio dos achados anatomopatológicos pulmonares e cardíacos, evolução clínica e sobrevida em 37 dias.Métodos Foram utilizados 50 ratos machos Wistar divididos em quatro grupos, sendo um controle (n = 10). Os três grupos restantes foram submetidos à inoculação de MCT (60 mg/kg i.p.) e ficaram sob o seu efeito por 15 (n = 10), 30 (n = 10) e 37 dias (n = 20). Ao final de cada período, os animais foram sacrificados, obtendo-se tecidos pulmonar e cardíaco para análise anatomopatológica e morfométrica. Empregou-se o teste Kruskal-Wallis, considerando nível de significância de 5%.Resultados Nos pulmões dos animais MCT foram constatadas lesões referentes à arteriopatia pulmonar, incluindo muscularização das arteríolas, hipertrofia da camada média e lesões neointimais concêntricas. Lesões complexas foram observadas nos grupos MCT, descritas como plexiforme e do “tipo” plexiforme (plexiform-like). A hipertrofia do ventrículo direito foi constatada pelo aumento da espessura e diâmetro dos cardiomiócitos e pelo aumento significativo da espessura da parede do ventrículo direito (p<0,0000).Conclusão O modelo foi capaz de gerar arteriopatia pulmonar moderada-grave associada à hipertrofia do ventrículo direito secundária, com sobrevida de 50% em 37 dias. De nosso conhecimento, este estudo foi o primeiro a constatar a presença de lesões vasculares complexas, semelhantes às observadas em pacientes com hipertensão arterial pulmonar grave, em modelo isolado de MCT. (Arq Bras Cardiol. 2020; 115(3):480-490)

Abstract P091: New Rho-kinase Inhibitors Reduce Cardiac Dysfunction And Vascular Remodeling In Pulmonary Hypertension In Rats

Pulmonary hypertension (PH) is characterized by extensive pulmonary vascular remodeling, leading to right ventricle (RV) hypertrophy and dysfunction. Since Rho kinases (ROCK) play a key role in smooth muscle proliferation and cardiomyocyte hypertrophy, this work evaluated the effects of ROCK inhibition by LASSBio-2020 and LASSBio-2065 on monocrotaline (MCT)-induced PH. After single injection of MCT (60 mg/kg i.p.), male Wistar rats were randomly divided in groups and treated with vehicle, LASSBio-2020 or LASSBio-2065 (60 μmol/kg/day, i.p.). Table 1 shows summarized data. After 14 days, ROCK inhibitors reduced pulmonary vascular resistance, indicated by the ratio of pulmonary acceleration time and ejection time (PAT/TET; p&lt; 0.05) and medial wall thickness of distal pulmonary arterioles (p&lt; 0.05). LASSBio-2020 and LASSBio-2065 also reduced Fulton index of RV hypertrophy (p&lt; 0.05) and RV afterload, as shown by recovery of RV cardiac output (p&lt; 0.05) and arterial elastance (p&lt; 0.05). ROCK inhibitors improved diastolic function since both compounds reduced RV end-diastolic pressures (RVEDP) and Tau, measured through catheterization. Therefore, ROCK inhibition by LASSBio-2020 and LASSBio-2065 reverted functional and morphological alterations in PH rats and may represent a useful alternative for management of PH-associated RV dysfunction.

Transplantation of viable mitochondria improves right ventricular performance and pulmonary artery remodeling in rats with pulmonary arterial hypertension

ObjectiveBecause mitochondrial dysfunction is a key factor in the progression of pulmonary hypertension, this study tested the hypothesis that transplantation of exogenous viable mitochondria can reverse pulmonary artery remodeling and restore right ventricular performance in pulmonary hypertension. MethodsPulmonary hypertension was induced by parenteral injection of monocrotaline (60 mg/kg) and creation of a left-to-right shunt aortocaval fistula in rats. Three weeks after creation of fistula, the animals were randomly assigned to receive intravenous delivery of placebo solution or allogeneic mitochondria once weekly for 3 consecutive weeks. Mitochondria (100 μg) were isolated from the freshly harvested soleus muscles of naïve rats. Transthoracic echocardiography was performed at 3 weeks after mitochondrial delivery. ResultsEx vivo heart-lung block images acquired by an IVIS Spectrum (PerkinElmer, Waltham, Mass) imaging system confirmed the enhancement of MitoTracker (Invitrogen, Carlsbad, Calif) fluorescence in the pulmonary arteries. Mitochondria transplantation significantly increased lung tissue adenosine triphosphate concentrations and improved right ventricular performance, as evidenced by a reduction in serum levels of B-type natriuretic peptide and ventricular diameter. Right ventricular mass and wall thickness were restored in the mitochondrial group. In the pulmonary arteries of rats that received mitochondrial treatment, vascular smooth muscle cells expressed higher levels of α-smooth muscle actin and smooth muscle myosin heavy chain II, indicating the maintenance of the nonproliferative, contractile phenotype. The hyper-reactivity of isolated pulmonary arteries to α-adrenergic stimulation was also attenuated after mitochondrial transplantation. ConclusionsTransplantation of viable mitochondria can restore the contractile phenotype and vasoreactivity of the pulmonary artery, thereby reducing the afterload and right ventricular remodeling in rats with established pulmonary hypertension. The improvement in overall right ventricular performance suggests that mitochondrial transplantation can be a revolutionary clinical therapeutic option for the management of pulmonary hypertension.

Abstract MP172: Y-chromosome Gene, Uty, Confers Male Protection Against Pulmonary Hypertension by Mediating Pro-inflammatory Chemokine Effects

Background: Idiopathic pulmonary arterial hypertension (PAH) is a terminal vascular lung disease characterized by increased PA pressure resulting in right ventricular (RV) failure and death. For reasons largely unknown, PAH is up to 4x more prevalent in females. We published that the Y-Chromosome (Chrm) is protective against hypoxia (Hx)-induced pulmonary hypertension (PH) in mice and identified four Y-Chrm genes expressed in the lung. Here, we identify the protective Y-Chrm gene, investigate its mechanism and demonstrate a novel therapeutic approach. Methods and Results: To test the effect of Y-Chrm candidate genes on PH development, we knocked down (KD) each Y-Chrm gene via sequential intratracheal instillation of siRNA in the lungs of male mice exposed to Hx. KD of Y-Chrm gene Uty, but none of the other genes, resulted in more severe PH measured by increased RV systolic pressure (RVSP) and decreased pulmonary arterial acceleration time (PAAT) compared to control (n=4/group; RVSP: Uty-KD= 48.93mmHg, Control= 37.33mmHg, p=0.04; PAAT: Uty-KD= 11.88ms, Control= 14.43ms, p=0.01). RNAseq analysis (Uty-KD vs Control) revealed an increase in pro-inflammatory cytokines Cxcl9 (Log2FC: 1.3, p-adjusted=0.05) and Cxcl10 (Log2FC: 0.9, p-adjusted=0.002). We found Cxcl9/10 significantly upregulated in human PAH lungs vs healthy and female PAH lungs vs male (RT-qPCR). Fluorescent in-situ hybridization revealed Uty and Cxcl9/10 expression co-localized in CD68 + macrophages within the lung. Treatment of human pulmonary artery endothelial cells (PAEC) with Cxcl9/10 resulted in significantly increased apoptosis. We inhibited Cxcl9/10 activity in female rats 14 days post monocrotaline (MCT) injection by treating them with a small molecular inhibitor. Treated rats (n=6) had less severe PH than vehicle-treated controls (n=5) when measured 28-days post MCT (RVSP: Treated= 36.75mmHg, Vehicle=43.62 mmHg, p=0.03; PAAT: Treated= 26.7ms, Vehicle=20 ms, p=0.01; RV hypertrophy index (RV/(LV+IVS)): Treated= 0.48, Vehicle= 0.35, p=0.01). Conclusion: Y-Chrm gene, Uty, is protective against PH. Uty inhibition increases pro-inflammatory cytokines Cxcl9/10 which contribute to PAEC death. Inhibition of Cxcl9/10 activity may provide a novel therapy for the treatment of PH.

Protective effect of nicotinamide and l-arginine against monocrotaline-induced pulmonary hypertension in rats: gender dependence

BackgroundThe purpose of this paper was to examine the effects of nicotinamide (ND) and l-arginine (l-ARG) on pulmonary vascular and heart changes induced by pulmonary hypertension in rats in a gender-dependent way.MethodsExperiments were performed on male (M) and female (F) rats. PAH was induced via monocrotaline injection (sc, 60/kg B.W.) on day one of the 23-day observational period. After that, the animals were sacrificed, hearts removed and weighed and the papillary muscles isolated to measure force of contraction (Fc). Morphological changes of pulmonary vessels were also examined.ResultsMixed diet supplementation with l-ARG + ND prevented highly significant right ventricle enlargement induced by PAH in both, male and female rats. Weight ratios between the right ventricle (RV) on one side and the left ventricle with septum on the other (LV + S) decreased from 0.46 ± 0.016 g to 0.29 ± 0.006 g in males and from 0.63 ± 0.03 g to 0.24 ± 0.008 g in females, n = 6, p < 0.001. Additionally, PAH increased basal contractility in female groups, and each of the diet allocations (l-ARG, ND, and mixed) were found to restore contractility to control values. All diet protocols in male and female restored decreased responsiveness of the myocardium to norepinephrine in hearts obtained from rats with PAH and prevented vascular changes observed in pulmonary hypertension (thickness of blood vessels and cell infiltration).ConclusionOur study suggests that l-arginine, nicotinamide or both play a positive role in right ventricle function or the process reducing pulmonary vascular remodeling especially in a gender-independent way.

3-Bromopyruvate ameliorates pulmonary arterial hypertension by improving mitochondrial metabolism

AimsAbnormal mitochondrial metabolism is an essential factor for excessive proliferation of pulmonary artery smooth muscle cells (PASMCs), which drives the pathological process of pulmonary arterial hypertension (PAH). 3-Bromopyruvate (3-BrPA) is an effective glycolytic inhibitor that improves mitochondrial metabolism, thereby repressing anomalous cell proliferation. Main methodsAn experimental PAH model was established by injection of monocrotaline (MCT) in male Sprague Dawley rats, following which rats were assigned to three groups: control, MCT, and 3-BrPA groups. Three days post injection of MCT, rats were treated with 3-BrPA or vehicle for 4 weeks. At the end of the study, hemodynamic data were measured to confirm PAH condition. Indicators of pulmonary arterial and right ventricular (RV) remodeling as well as the proliferative ability of PASMCs were assayed. Additionally, mitochondrial morphology and function, and antiglycolytic and antiproliferative pathways and genes were analyzed. Key findingsTreatment with 3-BrPA effectively improved pulmonary vascular remodeling and right ventricular function, inhibited PASMC proliferation, and preserved mitochondrial morphology and function. Besides, 3-BrPA treatment inhibited the PI3K/AKT/mTOR pathway and regulated the expression of antiproliferative genes in PASMCs. However, bloody ascites, bloating, and cirrhosis of organs were observed in some 3-BrPA treated rats. Significance3-BrPA acts as an important glycolytic inhibitor to improve energy metabolism and reverse the course of PAH. However, 3-BrPA is associated with side effects in MCT-induced rats, indicating that it should be caution in drug delivery dosage, and further studies are needed to evaluate this toxicological mechanism.

Non-invasive detection of arrhythmogenic foci of atria by using the cardioelectric field on the surface of the body during experimental pulmonary hypertension

Aim. The potential distribution of the cardioelectric field on the body surface during the initial atrial activity and the sequence of depolarization of the atrial subepicardium in rats with experimentally induced pulmonary hypertension were compared. This work is devoted to non-invasive detection of arrhythmogenic foci of atria by using the cardioelectric field on the body surface during experimental pulmonary hypertension.Materials and methods. The method of cardioelectrochronotopography has been used to study the electric field of the heart on the body surface and the sequence of propagation of the excitation wave along the atrial epicardium in rats with experimentally induced pulmonary hypertension caused by a single injection of monocrotaline (60 mg / kg, four weeks after drug administration).Results. Pulmonary hypertension causes the appearance of an additional focus of initial excitation in the area of the pulmonary vein lacunae, which leads to an increase in the heterogeneity of the propagation of the excitation wave along the atrial epicardium. The appearance of the additional excitation focus in the mouths of the pulmonary veins in the left atrium changes the picture of the sequence of depolarization of the atrial epicardium. The heterogeneity of the propagation of the excitation wave along the atrial epicardium is reflected in a different arrangement of zones of positive and negative cardioelectric potentials on the body surface before and during the P-wave in comparison with the initial state.Conclusion. Induced pulmonary hypertension contributes to the appearance of an additional focus of initial excitation in the area of the sleeves of the pulmonary veins of the left atrium in rats. This leads to an increase in the heterogeneity of the propagation of the excitation wave along the atrial epicardium. This is also reflected in the change in the arrangement of the zones of positive and negative cardioelectric potentials on the body surface before and during the P-wave in comparison with the initial state.

Influence of gender in monocrotaline and chronic hypoxia induced pulmonary hypertension in obese rats and mice

BackgroundObesity and pulmonary hypertension (PH) share common characteristics, such as augmented inflammation and oxidative stress. However, the exact role of obesity in the pathology of PH is largely uninvestigated. Therefore, we have hypothesized that in the context of obesity the gender difference may have influence on development of PH in animal models of this disease.MethodsAnimal experiments were conducted in monocrotaline (MCT) and chronic hypoxia (HOX) models of PH. Lean and obese Zucker rats or B6 mice of both genders were used for MCT or HOX models, respectively. Echocardiography, hemodynamic measurements, histology and immuno-histochemistry were performed to analyze various parameters, such as right ventricular function and hypertrophy, hemodynamics, pulmonary vascular remodeling and lung inflammation.ResultsBoth lean and obese male and female Zucker rats developed PH after a single MCT injection. However, negligible differences were seen between lean and obese male rats in terms of PH severity at the end stage of disease. Conversely, a more prominent and severe PH was observed in obese female rats compared to their lean counterparts. In contrast, HOX induced PH in lean and obese, male and female mice did not show any apparent differences.ConclusionGender influences PH severity in obese MCT-injected rats. It is also an important factor associated with altered inflammation. However, further research is necessary to investigate and reveal the underlying mechanisms.

Silibinin Upregulates CXCR4 Expression in Cultured Bone Marrow Cells (BMCs) Especially in Pulmonary Arterial Hypertension Rat Model.

Previously we reported that silibinin ameliorated pulmonary arterial hypertension (PAH) in rat PAH models, possibly through the suppression of the CXCR4/SDF-1, until the point where PAH became a severe and irreversible condition. To further investigate how silibinin ameliorates PAH, we first attempted to clarify its effect on bone marrow cells (BMCs), since the CXCR4/SDF-1 axis is known to regulate stem cell migration and attachment in BM niches. Rat PAH models were established through a combination of a single subcutaneous injection of monocrotaline (MCT) and chronic hypoxic conditions (10% O2). BMCs were harvested and cultured, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and flow cytometry (FCM) were performed to investigate whether silibinin affected CXCR4 expression. Silibinin upregulated the gene expression of stem cell related markers CXCR4, SDF-1, SCF, and c-Kit, inflammatory markers IL-6 and TNFα, mesenchymal stem cell (MSC)-related markers CD44 and CD29, and the granulocyte/monocyte-macrophage marker CD14 in cultured BM in PAH rats, but not in normal rats, except CXCR4. FCM showed that silibinin increased the CXCR4-positive cell population in a granulocyte fraction of cultured BMCs. However, immunohistochemical (IHC) staining showed no significant change in CXCR4 expression in the BM of the tibias. These results suggest that silibinin increases the expression of CXCR4 in BM, and the increased CXCR4-positive cells could be granulocytes/monocyte-macrophages.

Icotinib Attenuates Monocrotaline-Induced Pulmonary Hypertension by Preventing Pulmonary Arterial Smooth Muscle Cell Dysfunction.

Aberrant activation of epidermal growth factor receptor (EGFR) signaling pathway is associated with the pathogenesis of pulmonary hypertension (PH). However, the effect of icotinib, a first generation of EGFR tyrosine kinase inhibitor (EGFR-TKI), on PH remains to be elucidated. PH rat model was established by a single intraperitoneal injection of monocrotaline (MCT, 60 mg/kg). Icotinib (15, 30, and 60 mg/kg/day) was administered by oral gavage from the day of MCT injection. After 4 weeks, hemodynamic parameters and histological changes of the pulmonary arterial vessels were assessed, and the phenotypic switching of pulmonary arterial smooth muscle cells (PASMCs) was determined in vivo. Moreover, the effects of icotinib (10 µM) on epidermal growth factor (EGF, 50 ng/ml)-stimulated proliferation, migration, and phenotypic switching of human PASMCs were explored in vitro. Icotinib significantly reduced the right ventricular systolic pressure and right ventricle hypertrophy index in rats with MCT-induced PH. Moreover, icotinib improved MCT-induced pulmonary vascular remodeling. The expression of contractile marker (smooth muscle 22 alpha (SM22α)) and synthetic markers (osteopontin (OPN) and vimentin) in pulmonary artery was restored by icotinib treatment. In vitro, icotinib suppressed EGF-induced PASMCs proliferation and migration. Meanwhile, icotinib inhibited EGF-induced downregulation of α-smooth muscle actin and SM22α and upregulation of OPN and Collagen I in PASMCs, suggesting that icotinib could inhibit EGF-induced phenotypic switching of PASMCs. Mechanistically, these effects of icotinib were associated with the inhibition of EGFR-Akt/ERK signaling pathway. Icotinib can attenuate MCT-induced pulmonary vascular remodeling and improve PH. This effect of icotinib might be attributed to preventing PASMC dysfunction by inhibiting EGFR-Akt/ERK signaling pathway.

Novel angiogenesis strategy to ameliorate pulmonary hypertension

ObjectiveTo select a suitable combination of classic angiogenic and vascular stabilization factors to improve the proliferation and maturity of neovascularization of lung tissue in a rat pulmonary arterial hypertension (PAH) model. MethodsPAH rat model was established by intraperitoneal injection of monocrotaline. Proangiogenic factors hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF), as well as vascular stabilization factors angiopoietin-1 (Ang-1), platelet-derived growth factor, and transforming growth factor-beta were transfected by pairs into the lung tissue of rats with PAH through lentivirus. Four weeks later, pulmonary artery angiography and hemodynamic parameters were determined to testify the remission of PAH. Immunofluorescence staining and Western blot were performed to investigate the structure and function of neovascularization. ResultsThe pulmonary artery pressure and weight index of the right ventricle in HGF+Ang-1 and VEGF+Ang-1 groups were significantly decreased compared with vehicle group. The contrast medium filling time and right pulmonary artery root diameter were also significantly decreased. In addition, the maturity and perfusion of neovascularization in HGF+Ang-1 and VEGF+Ang-1 groups were promoted compared to vehicle group, and vascular leakage was reduced. Finally, the adherens junction integrity of vascular endothelial cells in HGF+Ang-1 and VEGF+Ang-1 combinations was upregulated compared with other combinations. ConclusionsHGF+Ang-1 transfection and VEGF+Ang-1 transfection alleviate PAH by promoting maturation and stability of new blood vessels, which may be potential candidates for PAH treatment.

Early progression of pulmonary hypertension in the monocrotaline model in males is associated with increased lung permeability

BackgroundThe mechanisms involved in pulmonary hypertension (PH) development in patients and pre-clinical models are poorly understood. PH has a well-established sex dimorphism in patients with increased frequency of PH in females, and more severe disease with poor survival prognosis in males. Previously, we found that heme signaling plays an essential role in the development phase of the Sugen/Hypoxia (SU/Hx) model. This study is focused on the elucidation of sex differences in mechanisms of PH development related to heme action at the early stage of the monocrotaline (MCT) PH model.MethodsRats received MCT injection (60 mg/kg, i.p.) and followed for 14 days to investigate early disease changes. Hemodynamic parameters were recorded at the end of the study; plasma, lung homogenates, and nuclear fractions were used for the evaluation of protein levels.ResultsOur data indicate that on day 14, rats did not show any significant increase in the Fulton index due to the early disease phase. However, the right ventricular systolic pressure was significantly increased in male rats, while female rats showed only a trend. Interestingly, only males demonstrated an increased lung-to-bodyweight ratio that indicated lung edema. Indeed, lung histology confirmed severe perivascular edema in males. Previously, we have reported that the increased perivascular edema in SU/Hx model correlated with intravascular hemolysis and activated heme signaling. Here, we found that elevated free hemoglobin levels and perivascular edema were increased, specifically in males showing more rapid progress of PH. A high level of heme carrier protein 1 (HCP-1), which is involved in heme uptake from the bloodstream into the cells, was also found elevated in the lungs of males. The upregulation of heme oxygenase in males indicated increased intracellular heme catabolism. Increased heme signaling resulted in the activation of heme-mediated barrier-disruptive mechanisms. Thus, hemolysis in males can be responsible for increased permeability of the lungs and early disease development.ConclusionsOur study indicates the importance of barrier-disruptive mechanisms as an earlier event in the induction of pulmonary hypertension. Importantly, males are more susceptible to hemolysis and develop PH earlier than females.

TRPM4 Modulates Right Ventricular Remodeling Under Pressure Load Accompanied With Decreased Expression Level

Survival of patients with congenital heart defects including increased right ventricular pressure load (ie, tetralogy of Fallot) or pulmonary hypertension is dependent on the function of the right ventricle (RV). RV remodeling has several effects with progressive transition from compensated status to heart failure. Transient receptor potential melastatin 4 (TRPM4) forms cation channels expressed in myocardium, which was shown to modulate cardiac remodeling in the left ventricle of mice. Aim of this study was to identify the role of TRPM4 for contractile function and remodeling of the RV in a rat model of right ventricular pressure load. We performed experiments with untreated rats and under monocrotaline (MCT)-induced pressure load comparing wild-type (Trpm4+/+) and TRPM4-deficient (Trpm4-/-) rats. RV function was characterized by echocardiography and contractility measurements of isolated papillary muscles. RV hypertrophy was investigated by echocardiography and by determination of hypertrophy indices. Pulmonary arterial remodeling was evaluated by echocardiography and histology. TRPM4 protein expression in RV of human, rat and mouse was detected by Western blot and quantified in rat. TRPM4 proteins were detected in RV myocardium of rat and mouse, which were not detectable in TRPM4-deficient animals. Proteins of the same size were found in RV of a pediatric patient with tetralogy of Fallot. In untreated status, Trpm4+/+ and Trpm4-/- rats showed comparable RV contractile function and dimensions. Under pressure load (42 days after MCT injection), RV hypertrophy was significantly increased in Trpm4-/- rats compared with Trpm4+/+ controls, whereas MCT-mediated alterations in cardiac contractility and pulmonary arterial remodeling were not affected by TRPM4 inactivation in rats. Finally, TRPM4 protein expression in RV was drastically reduced in MCT-treated rats, whereas left ventricle of the same animals showed no alteration in TRPM4 expression. Right ventricular pressure load evoked by MCT treatment in rats leads to a prominent downregulation of TRPM4 protein expression in the RV and complete deletion of TRPM4 expression aggravates right ventricular hypertrophy. Thus, therapeutic modulation of TRPM4 expression and activity might represent a novel approach to target right ventricular remodeling in patients with pulmonary hypertension or otherwise loaded RV.