endothelin-1 and Hypertrophy--Right-Ventricular

To study the association between hepatocyte growth factor (HGF) and treatment response in mice with hypoxic pulmonary arterial hypertension (HPAH) and the possibility of HGF as a new targeted drug for HPAH.. After successful modeling, the HPAH model mice were randomly divided into two groups: HPAH group and HGF treatment group (tail vein injection of recombinant mouse HGF 1 mg/kg), with 10 mice in each group. Ten normal mice were used as the control group. After 5 weeks, echocardiography was used to measure tricuspid peak velocity, right ventricular systolic pressure, right ventricular hypertrophy index, and right ventricular/body weight ratio; the Griess method was used to measure the content of nitric oxide in serum; ELISA was used to measure the serum level of endothelin-1; transmission electron microscopy was used to observe changes in the ultrastructure of pulmonary artery.. Compared with the HGF treatment and normal control groups, the HPAH group had significantly higher tricuspid peak velocity, right ventricular systolic pressure, right ventricular hypertrophy index, and right ventricular/body weight ratio (. Increasing serum HGF level can alleviate the impact of HPAH on the cardiovascular system of mice, possibly by repairing endothelial cell injury, improving vascular remodeling, and restoring the normal vasomotor function of pulmonary vessels.

Topics: Animals; Body Weight; Endothelial Cells; Endothelin-1; Hepatocyte Growth Factor; Hypertrophy, Right Ventricular; Hypoxia; Mice; Nitric Oxide; Pulmonary Arterial Hypertension

Inflammation is a major pathological feature of pulmonary arterial hypertension (PAH), particularly in the context of inflammatory conditions such as systemic sclerosis (SSc). The endothelin system and anti-endothelin A receptor (ET. Serum levels of anti-ET. Anti-ET. This study provides evidence for an anti-inflammatory role of ET

Topics: Animals; Autoantibodies; Endothelin-1; Familial Primary Pulmonary Hypertension; Humans; Hypertrophy, Right Ventricular; Inflammation; Mice; Pulmonary Arterial Hypertension; Receptor, Endothelin B; Scleroderma, Systemic

Pulmonary hypertension (PH) causes cardiac hypertrophy in the right ventricle (RV) and eventually leads to RV failure due to persistently elevated ventricular afterload. We hypothesized that the mechanical stress on the RV associated with increased afterload impairs vasodilator function of the right coronary artery (RCA) in PH. Coronary vascular response was assessed using microangiography with synchrotron radiation (SR) in two well-established PH rat models, monocrotaline injection or the combined exposure to chronic hypoxia and vascular endothelial growth factor receptor blockade with Su5416 (SuHx model). In the SuHx model, the effect of the treatment with the nonselective endothelin-1 receptor antagonist (ERA), macitentan, was also examined. Myocardial viability was determined in SuHx model rats, using

Topics: Animals; Antihypertensive Agents; Coronary Angiography; Coronary Vessels; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Monocrotaline; Predictive Value of Tests; Pulmonary Arterial Hypertension; Pyrimidines; Pyrroles; Rats, Sprague-Dawley; Severity of Illness Index; Sulfonamides; Synchrotrons; Vasodilation; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

Heart failure with reduced ejection fraction (HFrEF) causes lung remodelling with myofibroblasts proliferation and fibrosis leading to a restrictive lung syndrome with pulmonary hypertension (PH) and right ventricular (RV) dysfunction. PBI-4050 is a first-in-class anti-fibrotic, anti-inflammatory, and anti-proliferative compound. The present study evaluated the therapeutic impact of PBI-4050 on PH in an HFrEF model.. HFrEF was induced after myocardial infarction (MI) in rats. Two weeks later, sham-operated and MI groups received PBI-4050 (200 mg/kg/day by gavage) or saline for 3 weeks. Animals were analysed according to infarct size as large (≥30% left ventricle) or medium MI (<30%). Large MI caused PH and RV hypertrophy (RVH) with a restrictive lung syndrome. PBI-4050 did not adversely affect left ventricular (LV) function but markedly reduced PH and RVH and improved RV dysfunction. PBI-4050 reduced lung remodelling and improved respiratory compliance with decreased lung fibrosis, alveolar wall cellular proliferation and α-smooth muscle actin expression. The increased expression of endothelin-1 (ET-1), transforming growth factor beta (TGF-β), interleukin-6 (IL-6) and of tissue inhibitor of metalloprotease-1 in the lungs from HFrEF were reduced with PBI-4050 therapy. Activation of isolated human lung fibroblasts (HLFs) to a myofibroblastic pro-fibrogenic phenotype was markedly reduced by PBI-4050. The fatty acid receptor GPR84 was increased in HFrEF lungs and in activated HLFs, and reduced by PBI-4050. GPR84 agonists activated fibrogenesis in HLFs and finally, PBI-4050 reduced ERK1/2 phosphorylation.. PBI-4050 reduces PH and RVH in HFrEF by decreasing lung fibrosis and remodelling. This novel agent decreases the associated restrictive lung syndrome and recovers RV function. A contributing mechanism involves reducing the activation of lung fibroblasts by IL-6, TGF-β, and ET-1 by antagonism of GPR84 and reduced ERK1/2 phosphorylation. PBI-4050 is a novel promising therapy for targeting lung remodelling in group II PH.

Topics: Acetates; Animals; Cells, Cultured; Disease Models, Animal; Endothelin-1; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Fibrosis; Heart Failure; Heart Ventricles; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Interleukin-6; Lung; Male; Phosphorylation; Pulmonary Fibrosis; Rats, Wistar; Receptors, G-Protein-Coupled; Signal Transduction; Transforming Growth Factor beta; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

Cerium oxide nanoparticles (CeO. Pulmonary hypertension was induced in albino rats by a single subcutaneous injection of MCT (60 mg/kg). Rats received either single CeO. CeO

Topics: Animals; Apoptosis; Cardiotonic Agents; Cerium; Electrocardiography; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Nanoparticles; Nucleosides; Organ Size; Oxidative Stress; Poisons; Rats; Rats, Sprague-Dawley; Respiratory Function Tests; Triazoles

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance, leading to right ventricular failure and death. Recent studies have suggested that chronic inflammatory processes are involved in the pathogenesis of PAH. Several studies have demonstrated that betaine possesses outstanding anti-inflammatory effects. However, whether betaine exerts protective effects on PAH by inhibiting inflammatory responses in the lungs needs to be explored. To test our hypothesis, we aimed to investigate the effects of betaine on monocrotaline-induced PAH in rats and attempted to further clarify the possible mechanisms.. PAH was induced by monocrotaline (50 mg/kg) and oral administration of betaine (100, 200, and 400 mg/kg/day). The mean pulmonary arterial pressure, right ventricular systolic pressure, and right ventricle hypertrophy index were used to evaluate the development of PAH. Hematoxylin and eosin staining and Masson staining were performed to measure the extents of vascular remodeling and proliferation in fibrous tissue. Monocyte chemoattractant protein-1 (MCP-1) and endothelin-1 (ET-1) were also detected by immunohistochemical staining. Nuclear factor-κB (NF-κB), tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β) were assessed by Western blot.. This study showed that betaine improved the abnormalities in right ventricular systolic pressure, mean pulmonary arterial pressure, right ventricle hypertrophy index, and pulmonary arterial remodeling induced by monocrotaline compared with the PAH group. The levels of MCP-1 and ET-1 also decreased. Western blot indicated that the protein expression levels of NF-κB, TNF-α, and IL-1β significantly decreased (. Our study demonstrated that betaine attenuated PAH through its anti-inflammatory effects. Hence, the present data may offer novel targets and promising pharmacological perspectives for treating monocrotaline-induced PAH.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Betaine; Biomarkers; Chemokine CCL2; Cytokines; Disease Models, Animal; Endothelin-1; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Inflammation Mediators; Male; Monocrotaline; Myocardium; NF-kappa B; Pulmonary Artery; Rats

Pulmonary arterial hypertension is associated with a decreased antioxidant capacity. However, neither the contribution of reactive oxygen species to pulmonary vasoconstrictor sensitivity, nor the therapeutic efficacy of antioxidant strategies in this setting are known. We hypothesized that reactive oxygen species play a central role in mediating both vasoconstrictor and arterial remodeling components of severe pulmonary arterial hypertension. We examined the effect of the chemical antioxidant, TEMPOL, on right ventricular systolic pressure, vascular remodeling, and enhanced vasoconstrictor reactivity in both chronic hypoxia and hypoxia/SU5416 rat models of pulmonary hypertension. SU5416 is a vascular endothelial growth factor receptor antagonist and the combination of chronic hypoxia/SU5416 produces a model of severe pulmonary arterial hypertension with vascular plexiform lesions/fibrosis that is not present with chronic hypoxia alone. The major findings from this study are: 1) compared to hypoxia alone, hypoxia/SU5416 exposure caused more severe pulmonary hypertension, right ventricular hypertrophy, adventitial lesion formation, and greater vasoconstrictor sensitivity through a superoxide and Rho kinase-dependent Ca2+ sensitization mechanism. 2) Chronic hypoxia increased medial muscularization and superoxide levels, however there was no effect of SU5416 to augment these responses. 3) Treatment with TEMPOL decreased right ventricular systolic pressure in both hypoxia and hypoxia/SU5416 groups. 4) This effect of TEMPOL was associated with normalization of vasoconstrictor responses, but not arterial remodeling. Rather, medial hypertrophy and adventitial fibrotic lesion formation were more pronounced following chronic TEMPOL treatment in hypoxia/SU5416 rats. Our findings support a major role for reactive oxygen species in mediating enhanced vasoconstrictor reactivity and pulmonary hypertension in both chronic hypoxia and hypoxia/SU5416 rat models, despite a paradoxical effect of antioxidant therapy to exacerbate arterial remodeling in animals with severe pulmonary arterial hypertension in the hypoxia/SU5416 model.

Topics: Animals; Calcium; Cells, Cultured; Cyclic N-Oxides; Disease Models, Animal; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Spin Labels; Superoxides; Vasoconstriction

Pulmonary hypertension (PH), a serious complication of sickle cell disease (SCD), causes significant morbidity and mortality. Although a recent study determined that hemin release during hemolysis triggers endothelial dysfunction in SCD, the pathogenesis of SCD-PH remains incompletely defined. This study examines peroxisome proliferator-activated receptor γ (PPARγ) regulation in SCD-PH and endothelial dysfunction. PH and right ventricular hypertrophy were studied in Townes humanized sickle cell (SS) and littermate control (AA) mice. In parallel studies, SS or AA mice were gavaged with the PPARγ agonist, rosiglitazone (RSG), 10 mg/kg/day, or vehicle for 10 days. In vitro, human pulmonary artery endothelial cells (HPAECs) were treated with vehicle or hemin for 72 hours, and selected HPAECs were treated with RSG. SS mice developed PH and right ventricular hypertrophy associated with reduced lung levels of PPARγ and increased levels of microRNA-27a (miR-27a), v-ets avian erythroblastosis virus E26 oncogene homolog 1 (ETS1), endothelin-1 (ET-1), and markers of endothelial dysfunction (platelet/endothelial cell adhesion molecule 1 and E selectin). HPAECs treated with hemin had increased ETS1, miR-27a, ET-1, and endothelial dysfunction and decreased PPARγ levels. These derangements were attenuated by ETS1 knockdown, inhibition of miR-27a, or PPARγ overexpression. In SS mouse lung or in hemin-treated HPAECs, activation of PPARγ with RSG attenuated reductions in PPARγ and increases in miR-27a, ET-1, and markers of endothelial dysfunction. In SCD-PH pathogenesis, ETS1 stimulates increases in miR-27a levels that reduce PPARγ and increase ET-1 and endothelial dysfunction. PPARγ activation attenuated SCD-associated signaling derangements, suggesting a novel therapeutic approach to attenuate SCD-PH pathogenesis.

Topics: Anemia, Sickle Cell; Animals; Blood Pressure; Endothelial Cells; Endothelin-1; Gene Knockdown Techniques; Hemin; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Ligands; Lung; Mice; MicroRNAs; Models, Biological; PPAR gamma; Proto-Oncogene Protein c-ets-1; Pulmonary Artery; Rosiglitazone; Systole; Thiazolidinediones; Up-Regulation

Pulmonary arterial hypertension (PAH) is associated with inflammatory response but it is unknown whether it is associated with alterations in NNMT activity and MNA plasma concentration. Here we examined changes in NNMT-MNA pathway in PAH in rats and humans.. PAH in rats was induced by a single subcutaneous injection of MCT (60 mg/kg). Changes in NNMT activity in the lungs and liver (assessed as the rate of conversion of nicotinamide (NA) to MNA), changes in plasma concentration of MNA and its metabolites (analyzed by LC/MS) were analyzed in relation to PAH progression. PAH was characterized by right ventricular hypertrophy (gross morphology), cardiac dysfunction (by MRI), lung histopathology, lung ultrastructure, and ET-1 concentration in plasma. NO-dependent and PGI2-dependent function in isolated lungs was analyzed. In naive patients with idiopathic pulmonary hypertension (IPAH) characterized by hemodynamic and biochemical parameters MNA and its metabolites in plasma were also measured.. MCT-injected rats developed hypertrophy and functional impairment of the right ventricle, hypertrophy of the pulmonary arteries, endothelial ultrastructural defects and a progressive increase in ET-1 plasma concentration-findings all consistent with PAH development. In isolated lung, NO-dependent regulation of hypoxic pulmonary vasoconstriction was impaired, while PGI2 production (6-keto-PGF1α) was increased. NNMT activity increased progressively in the liver and in the lungs following MCT injection, and NNMT response was associated with an increase in MNA and 6-keto-PGF1α concentration in plasma. In IPAH patients plasma concentration of MNA was elevated as compared with healthy controls.. Progression of pulmonary hypertension is associated with the activation of the NNMT-MNA pathway in rats and humans. Given the vasoprotective activity of exogenous MNA, which was previously ascribed to PGI2 release, the activation of the endogenous NNMT-MNA pathway may play a compensatory role in PAH.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Animals; Case-Control Studies; Disease Models, Animal; Disease Progression; Endothelin-1; Epoprostenol; Female; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Liver; Lung; Male; Middle Aged; Monocrotaline; Niacinamide; Nicotinamide N-Methyltransferase; Nitric Oxide; Rats, Wistar; Signal Transduction; Time Factors; Ventricular Dysfunction, Right; Ventricular Function, Right

Pediatric pulmonary arterial hypertension (PAH) presents certain specific features. In this specific age group, experimental models to study the pathophysiology of PAH are lacking. To characterize hemodynamic, morphometric, and histological progression as well as the expression of neurohumoral factors and regulators of cardiac transcription in an infantile model of PAH induced by monocrotaline (MCT), eight-day-old Wistar rats were randomly injected with MCT (30 mg/kg, sc, n = 95) or equal volume of saline solution (n = 92). Animals were instrumented for biventricular hemodynamic recording 7, 14, and 21 days after MCT, whereas samples were collected at 1, 3, 7, 14, and 21 days after MCT. Different time point postinjections were defined for further analysis. Hearts and lungs were collected for morphometric characterization, assessment of right- and left-ventricle (RV and LV) cardiomyocyte diameter and collagen type-I and type-III ratio, RV collagen volume fraction, and pulmonary vessels wall thickness. mRNA quantification was undertaken for brain natriuretic peptide (BNP), endothelin-1 (ET-1), and for cardiac transcription regulators (HOP and Islet1). Animals treated with MCT at the 8th day of life presented RV hypertrophy since day 14 after MCT injection. There were no differences on the RV collagen volume fraction or collagen type-I and type-III ratio. Pulmonary vascular remodelling and PAH were present on day 21, which were accompanied by an increased expression of BNP, ET-1, HOP, and Islet1. The infantile model of MCT-induced PAH can be useful for the study of its pathophysiology and to test new therapeutic targets in pediatric age group.

Topics: Animals; Animals, Newborn; Collagen Type I; Collagen Type III; Disease Models, Animal; Endothelin-1; Female; Heart; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Male; Monocrotaline; Myocytes, Cardiac; Natriuretic Peptide, Brain; Pyrrolizidine Alkaloids; Rats; Rats, Wistar; RNA, Messenger; Time Factors; Transcription Factors

This study examines how heme biosynthesis modulation with δ-aminolevulinic acid (ALA) potentially functions to prevent 21-day hypoxia (10% oxygen)-induced pulmonary hypertension in mice and the effects of 24-h organoid culture with bovine pulmonary arteries (BPA) with the hypoxia and pulmonary hypertension mediator endothelin-1 (ET-1), with a focus on changes in superoxide and regulation of micro-RNA 204 (miR204) expression by src kinase phosphorylation of signal transducer and activator of transcription-3 (STAT3). The treatment of mice with ALA attenuated pulmonary hypertension (assessed through echo Doppler flow of the pulmonary valve, and direct measurements of right ventricular systolic pressure and right ventricular hypertrophy), increases in pulmonary arterial superoxide (detected by lucigenin), and decreases in lung miR204 and mitochondrial superoxide dismutase (SOD2) expression. ALA treatment of BPA attenuated ET-1-induced increases in mitochondrial superoxide (detected by MitoSox), STAT3 phosphorylation, and decreases in miR204 and SOD2 expression. Because ALA increases BPA protoporphyrin IX (a stimulator of guanylate cyclase) and cGMP-mediated protein kinase G (PKG) activity, the effects of the PKG activator 8-bromo-cGMP were examined and found to also attenuate the ET-1-induced increase in superoxide. ET-1 increased superoxide production and the detection of protoporphyrin IX fluorescence, suggesting oxidant conditions might impair heme biosynthesis by ferrochelatase. However, chronic hypoxia actually increased ferrochelatase activity in mouse pulmonary arteries. Thus, a reversal of factors increasing mitochondrial superoxide and oxidant effects that potentially influence remodeling signaling related to miR204 expression and perhaps iron availability needed for the biosynthesis of heme by the ferrochelatase reaction could be factors in the beneficial actions of ALA in pulmonary hypertension.

Topics: Aminolevulinic Acid; Animals; Endothelin-1; Ferrochelatase; Heme; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Mice, Inbred C57BL; MicroRNAs; Mitochondria; Pulmonary Artery; Superoxide Dismutase; Superoxides

Pulmonary hypertension is a fatal disease characterized by a progressive increase in pulmonary artery pressure accompanied by pulmonary vascular remodeling and increased vasomotor tone. Although some biological pathways have been identified in neonatal hypoxia-induced pulmonary hypertension (PH), little is known regarding the role of growth factors in the pathogenesis of PH in neonates. In this study, using a model of hypoxia-induced PH in neonatal mice, we demonstrate that the growth factor insulin-like growth factor-1 (IGF-1), a potent activator of the AKT signaling pathway, is involved in neonatal PH. After exposure to hypoxia, IGF-1 signaling is activated in pulmonary endothelial and smooth muscle cells in vitro, and the IGF-1 downstream signal pAKT(S473) is upregulated in lungs of neonatal mice. We found that IGF-1 regulates ET-1 expression in pulmonary endothelial cells and that IGF-1 expression is regulated by histone deacetylases (HDACs). In addition, there is a differential cytosine methylation site in the IGF-1 promoter region in response to neonatal hypoxia. Moreover, inhibition of HDACs with apicidin decreases neonatal hypoxia-induced global DNA methylation levels in lungs and specific cytosine methylation levels around the pulmonary IGF-1 promoter region. Finally, HDAC inhibition with apicidin reduces chronic hypoxia-induced activation of IGF-1/pAKT signaling in lungs and attenuates right ventricular hypertrophy and pulmonary vascular remodeling. Taken together, we conclude that IGF-1, which is epigenetically regulated, is involved in the pathogenesis of pulmonary hypertension in neonatal mice. This study implicates a novel HDAC/IGF-1 epigenetic pathway in the regulation of hypoxia-induced PH and warrants further study of the role of IGF-1 in neonatal pulmonary hypertensive disease.

Topics: Animals; Animals, Newborn; Arterial Pressure; Cells, Cultured; Disease Models, Animal; DNA Methylation; Endothelin-1; Epigenesis, Genetic; Gene Expression Regulation; Histone Deacetylase Inhibitors; Histone Deacetylases; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Insulin-Like Growth Factor I; Mice, Inbred C57BL; Phosphorylation; Promoter Regions, Genetic; Proto-Oncogene Proteins c-akt; Pulmonary Artery; RNA Interference; Signal Transduction; Time Factors; Transfection; Vascular Remodeling

Pulmonary arterial hypertension (PAH) causes right ventricular failure due to a gradual increase in pulmonary vascular resistance. The purposes of this study were to confirm the engraftment of human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) placed in the correct place in the lung and research on changes of hemodynamics, pulmonary pathology, immunomodulation and several gene expressions in monocrotaline (MCT)-induced PAH rat models after hUCB-MSCs transfusion. The rats were grouped as follows: the control (C) group; the M group (MCT 60 mg/kg); the U group (hUCB-MSCs transfusion). They received transfusions via the external jugular vein a week after MCT injection. The mean right ventricular pressure (RVP) was significantly reduced in the U group after the 2 week. The indicators of RV hypertrophy were significantly reduced in the U group at week 4. Reduced medial wall thickness in the pulmonary arteriole was noted in the U group at week 4. Reduced number of intra-acinar muscular pulmonary arteries was observed in the U group after 2 week. Protein expressions such as endothelin (ET)-1, endothelin receptor A (ERA), endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 significantly decreased at week 4. The decreased levels of ERA, eNOS and MMP-2 immunoreactivity were noted by immnohistochemical staining. After hUCB-MSCs were administered, there were the improvement of RVH and mean RVP. Reductions in several protein expressions and immunomodulation were also detected. It is suggested that hUCB-MSCs may be a promising therapeutic option for PAH.

Topics: Animals; Cytokines; Disease Models, Animal; Endothelin-1; Fetal Blood; Gene Expression Regulation; Hemodynamics; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Lung; Male; Matrix Metalloproteinase 2; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Monocrotaline; Nitric Oxide Synthase Type III; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A

Limited literature sources implicate mast-cell mediator chymase in the pathologies of pulmonary hypertension and pulmonary fibrosis. However, there is no evidence on the contribution of chymase to the development of pulmonary hypertension associated with lung fibrosis, which is an important medical condition linked with increased mortality of patients who already suffer from a life-threatening interstitial lung disease.The aim of this study was to investigate the role of chymase in this particular pulmonary hypertension form, by using a bleomycin-induced pulmonary hypertension model.Chymase inhibition resulted in attenuation of pulmonary hypertension and pulmonary fibrosis, as evident from improved haemodynamics, decreased right ventricular remodelling/hypertrophy, pulmonary vascular remodelling and lung fibrosis. These beneficial effects were associated with a strong tendency of reduction in mast cell number and activity, and significantly diminished chymase expression levels. Mechanistically, chymase inhibition led to attenuation of transforming growth factor β1 and matrix-metalloproteinase-2 contents in the lungs. Furthermore, chymase inhibition prevented big endothelin-1-induced vasoconstriction of the pulmonary arteries.Therefore, chymase plays a role in the pathogenesis of pulmonary hypertension associated with pulmonary fibrosis and may represent a promising therapeutic target. In addition, this study may provide valuable insights on the contribution of chymase in the pulmonary hypertension context, in general, regardless of the pulmonary hypertension form.

Topics: Animals; Bleomycin; Chymases; Disease Models, Animal; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Hemodynamics; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Lung; Mast Cells; Matrix Metalloproteinase 2; Mesocricetus; Pulmonary Artery; Pulmonary Fibrosis; Radioimmunoassay; Random Allocation; Transforming Growth Factor beta1

Pulmonary arterial hypertension (PAH) is a cardiovascular disorder characterized by elevated pulmonary artery pressure as a result of arterial wall thickening. Patients are 3-4 times more likely to be women than men. This gender discrepancy demonstrates a need for an animal model with similar sex differences. 4,4'-Methylenedianiline (DAPM) is an aromatic amine used industrially in the synthesis of polyurethanes. Chronic, intermittent treatment of male and female rats with DAPM resulted in medial hyperplasia of pulmonary arterioles, exclusively in females, coupled to increases in pulmonary arterial pressures. Significant increases in plasma levels of endothelin-1 (ET-1) and serotonin, but decreases in nitrite [Formula: see text], were observed in females treated with DAPM. A decrease was observed in the serum ratio of the estrogen metabolites 2-hydroxyestradiol (2-OHE1)/16α-hydroxyestrogen (16α-OHE1). In females, ET-1,[Formula: see text] , and 2-OHE1/16α-OHE1 were significantly correlated with peak pressure gradient, an indirect measure of pulmonary arterial pressure. Expression of the serotonin transport protein (SERT) was significantly higher in the arteries of DAPM-treated females. In vitro, DAPM induced human pulmonary vascular smooth muscle cell proliferation and serotonin uptake, both of which were inhibited by treatment with the estrogen receptor antagonist ICI 182,780 or the selective serotonin reuptake inhibitor fluoxetine. DAPM also induced the release of serotonin from human pulmonary endothelial cells in culture, which is blocked by ICI 182,780. Taken together, this suggests that DAPM-mediated dysregulation of serotonin transport is estrogen-receptor dependent. Thus, DAPM-induced PAH pathology may be a new tool to clarify the sex selectivity of PAH disease pathogenesis.

Topics: Aniline Compounds; Animals; Endocrine Disruptors; Endothelin-1; Epithelial Cells; Estrogens; Female; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Muscle, Smooth, Vascular; Nitric Oxide; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptors, Estrogen; RNA-Binding Proteins; Serotonin; Sex Characteristics

Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary arterial pressure and vascular resistance. Despite advances in therapy for PAH, its treatment and prognosis remain poor. We aimed to investigate whether the transplantation of bone marrow mesenchymal stem cells (MSCs) overexpressing hepatocyte growth factor (HGF), alone or in combination with granulocyte colony-stimulating factor (G-CSF), attenuates the development of experimental monocrotaline (MCT)-induced PAH. Three weeks after MCT administration, rats were divided into the following groups: (1) untreated (PAH); (2) HGF treated; (3) MSCs administered; (4) HGF-MSCs treated; and (5) HGF-MSCs plus G-CSF treated. After 3 weeks, hemodynamic changes, histomorphology, and angiogenesis were evaluated. To elucidate the molecular mechanisms of vascular remodeling and angiogenesis, serum levels of transforming growth factor (TGF)-β and endothelin-1 (ET-1) were measured, and the gene and protein expression levels of vascular cell adhesion molecule-1 (VCAM-1) and matrix metalloproteinase-9 (MMP-9) were determined. Compared with the PAH, MSC, and G-CSF groups, the HGF and HGF+G-CSF groups exhibited significantly reduced right ventricular hypertrophy and mean pulmonary arterial pressure (P < 0.05). Histologically, vessel muscularization or thickening and collagen deposition were also significantly decreased (P < 0.05). The number of vessels in the HGF+G-CSF group was higher than that in the other groups (P < 0.05). The TGF-β and ET-1 concentrations in the plasma of pulmonary hypertensive rats were markedly lower in the HGF and HGF+G-CSF groups (P < 0.05). Furthermore, HGF induced the expression of VCAM-1, and HGF treatment together with G-CSF synergistically stimulated MMP-9 expression. Transplanted HGF-MSCs combined with G-CSF potentially offer synergistic therapeutic benefit for the treatment of PAH.

Topics: Animals; Arterial Pressure; Cells, Cultured; Disease Models, Animal; Endothelin-1; Genetic Therapy; Granulocyte Colony-Stimulating Factor; Hepatocyte Growth Factor; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Matrix Metalloproteinase 9; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Neovascularization, Physiologic; Pulmonary Artery; Rats, Sprague-Dawley; Recovery of Function; Time Factors; Transforming Growth Factor beta; Vascular Cell Adhesion Molecule-1; Vascular Remodeling

Krüppel-like factor 4 (KLF4) is a transcription factor expressed in the vascular endothelium, where it promotes anti-inflammatory and anticoagulant states, and increases endothelial nitric oxide synthase expression. We examined the role of endothelial KLF4 in pulmonary arterial (PA) hypertension (PAH). Mice with endothelial KLF4 knockdown were exposed to hypoxia for 3 weeks, followed by measurement of right ventricular and PA pressures, pulmonary vascular muscularization, and right ventricular hypertrophy. The effect of KLF4 on target gene expression was assessed in lungs from these mice, verified in vitro by small interfering RNA (siRNA) knockdown of KLF4, and further studied at the promoter level with cotransfection experiments. KLF4 expression was measured in lung tissue from patients with PAH and normal control subjects. We found that, after hypoxia, right ventricular and PA pressures were significantly higher in KLF4 knockdown animals than controls. Knockdown animals also had more severe pulmonary vascular muscularization and right ventricular hypertrophy. KLF4 knockdown resulted in increased pulmonary expression of endothelin-1 and decreased expression of endothelial nitric oxide synthase, endothelin receptor subtype B, and prostacyclin synthase. Concordant findings were observed in vitro, both with siRNA knockdown of KLF4 and promoter activity assays. Finally, KLF4 expression was reduced in lungs from patients with PAH. In conclusion, endothelial KLF4 regulates the transcription of genes involved in key pathways implicated in PAH, and its loss exacerbates pulmonary hypertension in response to chronic hypoxia in mice. These results introduce a novel transcriptional modulator of PAH, with the potential of becoming a new therapeutic target.

Topics: Animals; Arterial Pressure; Case-Control Studies; Cells, Cultured; Cytochrome P-450 Enzyme System; Disease Models, Animal; Endothelial Cells; Endothelin-1; Familial Primary Pulmonary Hypertension; Human Umbilical Vein Endothelial Cells; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Intramolecular Oxidoreductases; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase Type III; Pulmonary Artery; Receptor, Endothelin B; RNA Interference; Time Factors; Transfection; Ventricular Function, Right; Ventricular Pressure

Topics: Animals; Endothelin-1; Endothelins; Female; Humans; Hypertrophy, Right Ventricular; Male; Receptor, Endothelin A; Up-Regulation; Ventricular Function, Right

Topics: Animals; Endothelin-1; Endothelins; Female; Humans; Hypertrophy, Right Ventricular; Male; Receptor, Endothelin A; Up-Regulation; Ventricular Function, Right

This study investigates whether endothelin-1 (ET-1) mediates monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) and right ventricular hypertrophy (RVH), and if so, whether the G-protein coupled receptor antagonist KMUP-1 (7-{2-[4-(2-chlorobenzene)piperazinyl]ethyl}-1,3-dimethylxanthine) inhibits ET-1-mediated PA constriction and the aforementioned pathological changes. In a chronic rat model, intraperitoneal MCT (60 mg/kg) induced PAH and increased PA medial wall thickening and RV/left ventricle + septum weight ratio on Day 21 after MCT injection. Treatment with sublingual KMUP-1 (2.5 mg/kg/day) for 21 days prevented these changes and restored vascular endothelial nitric oxide synthase (eNOS) immunohistochemical staining of lung tissues. Western blotting analysis demonstrated that KMUP-1 enhanced eNOS, soluble guanylate cyclase, and protein kinase G levels, and reduced ET-1 expression and inactivated Rho kinase II (ROCKII) in MCT-treated lung tissue over long-term administration. In MCT-treated rats, KMUP-1 decreased plasma ET-1 on Day 21. KMUP-1 (3.6 mg/kg) maximally appeared at 0.25 hours in the plasma and declined to basal levels within 24 hours after sublingual administration. In isolated PA of MCT-treated rats, compared with control and pretreatment with l-NG-nitroarginine methyl ester (100 μM), KMUP-1 (0.1-100 μM) inhibited ET-1 (0.01 μM)-induced vasoconstriction. Endothelium-denuded PA sustained higher contractility in the presence of KMUP-1. In a 24-hour culture of smooth muscle cells (i.e., PA smooth muscle cells or PASMCs), KMUP-1 (0.1-10 μM) inhibited RhoA- and ET-1-induced RhoA activation. KMUP-1 prevented MCT-induced PAH, PA wall thickening, and RVH by enhancing eNOS and suppressing ET-1/ROCKII expression. In vitro, KMUP-1 inhibited ET-1-induced PA constriction and ET-1-dependent/independent RhoA activation of PASMCs. In summary, KMUP-1 attenuates ET-1-induced/ET-1-mediated PA constriction, and could thus aid in the treatment of PAH caused by MCT.

Topics: Animals; Blood Pressure; Body Weight; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Endothelin-1; Guanylate Cyclase; Heart Rate; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; In Vitro Techniques; Male; Monocrotaline; Nitric Oxide Synthase Type III; Piperazines; Piperidines; Pulmonary Artery; Purines; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Receptors, G-Protein-Coupled; rho-Associated Kinases; rhoA GTP-Binding Protein; Signal Transduction; Sildenafil Citrate; Soluble Guanylyl Cyclase; Sulfonamides; Vasoconstriction; Xanthines

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance leading to right ventricular failure and death. Recent studies have suggested that chronic inflammatory processes are involved in the pathogenesis of PAH. However, the molecular and cellular mechanisms driving inflammation have not been fully elucidated.. To elucidate the roles of high mobility group box 1 protein (HMGB1), a ubiquitous DNA-binding protein with extracellular pro-inflammatory activity, in a rat model of PAH.. Male Sprague-Dawley rats were administered monocrotaline (MCT). Concentrations of HMGB1 in bronchoalveolar lavage fluid (BALF) and serum, and localization of HMGB1 in the lung were examined over time. The protective effects of anti-HMGB1 neutralizing antibody against MCT-induced PAH were tested.. HMGB1 levels in BALF were elevated 1 week after MCT injection, and this elevation preceded increases of other pro-inflammatory cytokines, such as TNF-α, and the development of PAH. In contrast, serum HMGB1 levels were elevated 4 weeks after MCT injection, at which time the rats began to die. Immunohistochemical analyses indicated that HMGB1 was translocated to the extranuclear space in periarterial infiltrating cells, alveolar macrophages, and bronchial epithelial cells of MCT-injected rats. Anti-HMGB1 neutralizing antibody protected rats against MCT-induced lung inflammation, thickening of the pulmonary artery wall, and elevation of right ventricular systolic pressure, and significantly improved the survival of the MCT-induced PAH rats.. Our results identify extracellular HMGB1 as a promoting factor for MCT-induced PAH. The blockade of HMGB1 activity improved survival of MCT-induced PAH rats, and thus might be a promising therapy for the treatment of PAH.

Topics: Animals; Bronchoalveolar Lavage Fluid; Chemokine CCL2; Disease Models, Animal; DNA-Binding Proteins; Endothelin-1; Hemodynamics; HMGB1 Protein; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Inflammation; Interleukin-1beta; Male; Monocrotaline; Pulmonary Artery; Random Allocation; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha; Vascular Resistance; Ventricular Dysfunction, Right

High mobility group box-1 (HMGB1), a proinflammatory cytokine, plays a pivotal role in tissue remodeling and angiogenesis, both of which are crucial for the pathogenesis of pulmonary arterial hypertension. In this study, we explored the relationship between HMGB1 and pulmonary hypertension and whether glycyrrhizin, an inhibitor of HMGB1, attenuates disease progression in an animal model of pulmonary hypertension induced by monocrotaline sodium (MCT).. After inducing pulmonary hypertension through a single subcutaneous injection of MCT (60 mg/kg) to Sprague-Dawley rats, we administered daily intraperitoneal injections of either glycyrrhizin (GLY, 50 mg/kg), an inhibitor of HMGB1, or saline (control) for either 4 or 6 weeks.. Expression levels of HMGB1 in serum increased from the second week after MCT injection and remained elevated throughout the experiment periods. Lung tissue levels of HMGB1 assessed by immunohistochemical staining at 4 weeks after MCT injection also increased. Chronic inhibition of HMGB1 by GLY treatment reduced the MCT-induced increase in right ventricular (RV) systolic pressure, RV hypertrophy (ratio of RV to [left ventricle + septum]), and pulmonary inflammation. MCT-induced muscularization of the pulmonary artery was also attenuated in the GLY-treated group. As assessed 6 weeks after MCT injection, the GLY-treated group exhibited increased survival (90% [18 of 20]) when compared with the control group (60% [12 of 20]; p =0.0027).. Glycyrrhizin, an inhibitor of HMGB1, attenuates pulmonary hypertension progression and pulmonary vascular remodeling in the MCT-induced pulmonary hypertension rat model. Further studies are needed to confirm the potential of HMGB1 as a novel therapeutic target for pulmonary hypertension.

Topics: Animals; Antihypertensive Agents; Arterial Pressure; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Glycyrrhizic Acid; HMGB1 Protein; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Muscle, Smooth, Vascular; Pneumonia; Pulmonary Artery; Rats, Sprague-Dawley; Time Factors; Vascular Remodeling; Ventricular Dysfunction, Right; Ventricular Function, Right

We investigated gene transfer with human hepatocyte growth factor (HGF) to suppress pulmonary arterial hypertension (PAH) produced by an arteriovenous shunt in a rabbit model. The rabbit model of advanced PAH was used to show that HGF targets pulmonary arteriolar endothelial cells and inhibits disease progression. In the PAH rabbit model transfected with the HGF gene, hemodynamic abnormalities and right ventricular hypertrophy were prevented, as confirmed by invasive measurements and electrocardiographic examinations. In addition to augmented expression of HGF, an increased number of pulmonary arterioles were detected by immunohistochemical analysis. Western Blot and real-time reverse transcriptase-polymerase chain reaction indicated increased protein and mRNA levels of HGF and endothelial nitricoxide synthase (eNOS) in lungs after HGF transfection. Notably, exogenous HGF reduced lung expression of endothelin-1 (ET-1), which was critically involved in PAH-related pathologic changes. Our results suggested that HGF transfection suppresses PAH induced by shunt flow through enhanced expression of HGF with subsequent regulation of the concentrations of eNOS and ET-1 secreted by endothelial cells thereby promoting angiogenesis in injured lung tissue.

Topics: Animals; Arterioles; Arteriovenous Shunt, Surgical; Blotting, Western; Carotid Artery, Common; Disease Models, Animal; Disease Progression; Electrocardiography; Endothelial Cells; Endothelin-1; Familial Primary Pulmonary Hypertension; Genetic Therapy; Hemodynamics; Hepatocyte Growth Factor; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Jugular Veins; Lung; Male; Neovascularization, Physiologic; Nitric Oxide Synthase Type III; Rabbits; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Transfection

The central pathway for oxygen-dependent control of red cell mass is the prolyl hydroxylase domain protein (PHD):hypoxia inducible factor (HIF) pathway. PHD site specifically prolyl hydroxylates the transcription factor HIF-α, thereby targeting the latter for degradation. Under hypoxia, this modification is attenuated, allowing stabilized HIF-α to activate target genes, including that for erythropoietin (EPO). Studies employing genetically modified mice point to Hif-2α, one of two main Hif-α isoforms, as being the critical regulator of Epo in the adult mouse. More recently, erythrocytosis patients with heterozygous point mutations in the HIF2A gene have been identified; whether these mutations were polymorphisms unrelated to the phenotype could not be ruled out. In the present report, we characterize a mouse line bearing a G536W missense mutation in the Hif2a gene that corresponds to the first such human mutation identified (G537W). We obtained mice bearing both heterozygous and homozygous mutations at this locus. We find that these mice display, in a mutation dose-dependent manner, erythrocytosis and pulmonary hypertension with a high degree of penetrance. These findings firmly establish missense mutations in HIF-2α as a cause of erythrocytosis, highlight the importance of this HIF-α isoform in erythropoiesis, and point to physiologic consequences of HIF-2α dysregulation.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Blood Gas Analysis; Cells, Cultured; Disease Models, Animal; Endothelin-1; Erythropoiesis; Erythropoietin; Gene Expression; Gene Knock-In Techniques; Genetic Association Studies; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Kidney; Lung; Mice; Mice, Inbred C57BL; Mutagenesis; Mutation, Missense; Polycythemia; Proto-Oncogene Proteins c-sis; Respiratory Rate; RNA, Messenger; Up-Regulation; Vascular Endothelial Growth Factor A

We sought to investigate the experimental therapeutic effects and mechanisms of iptakalim, a new adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP)) opener, on monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and right heart ventricle remodeling in rats.. Rats were injected with a single dose (50 mg/kg, ip) of MCT and given iptakalim (1, 3, and 9 mg/kg·per d, orally [po]) or saline for 28 days. The hemodynamic and morphometric parameters were assessed. Tissue and plasma samples were collected for histological and molecular analysis.. Treatment with iptakalim at daily oral doses of 1, 3, and 9 mg/kg from the day of MCT injection attenuated the high right ventricle systolic pressure (RVSP) and the increased weight ratio of right ventricle (RV) to left ventricle (LV) plus septum (S) (RV/(LV+S)), decreased heart rate (HR) and decreased mean arterial pressure (MAP), inhibited the RV myocardial tissue cell apoptosis, and the RV myocardial cell B-type natriuretic peptide (BNP) protein expression. Iptakalim also decreased the serum levels of nitric oxide (NO), endothelin 1 (ET-1), BNP, and the levels of NO, ET-1, and tumor necrosis factor-alpha (TNF-α) in the lung tissue.. These results indicate that iptakalim prevents MCT-induced PAH and RV remodeling and its mechanisms are related to inhibiting the pathological increases in NO, ET-1, BNP, and TNF-α, and Iptakalim may be a promising candidate for the treatment of PAH.

Topics: Animals; Endothelin-1; Familial Primary Pulmonary Hypertension; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; KATP Channels; Lung; Male; Monocrotaline; Natriuretic Peptide, Brain; Nitric Oxide; Propylamines; Rats; Rats, Wistar

Pulmonary arterial hypertension (PAH) is a progressive and a life-threatening disease with its high morbidity and mortality ratios. On searching for new shining targets in pathogenesis, we noticed, in our previous studies, urotensin-II (UII) in systemic sclerosis with potent angiogenic and pro-fibrotic features. Owing to the mimicking properties of UII with endothelin-1 (ET1), we attempted to investigate the effect of palosuran in a PAH rat model. Thirty rats were randomly divided into three groups, with each group comprising 10 rats: group 1 (control group) received the vehicle subcutaneously, instead of monocrotaline (MCT) and vehicle; group 2 (MCT group) received subcutaneous MCT and vehicle; and group 3 (MCT + palosuran group) received subcutaneous MCT and palosuran. Serum UII, ET1, transforming growth factor-β1 (TGF-β1) levels, pulmonary arteriolar pathology of different diameter vessels, and cardiac indices were evaluated. The ET1, TGF-β1, and UII levels were significantly diminished in the treatment group, similar to the controls (p < 0.001). Right ventricular hypertrophy index and mean pulmonary arterial pressure scores were also significantly reduced in the treatment group (p = 0.001). Finally, in the 50-125-μm diameter arterioles, in contrast to Groups 3 and 1, there was a statistically significant thickness (p < 0.01) in the arteriolar walls of rats in Group 2. The treatment effect on arteries of more than 125-μm diameters was found to be valuable but not significant. Owing to its healing effect on hemodynamic, histological, and biochemical parameters of MCT-induced PAH, palosuran as an antagonist of UII might be an optional treatment alternative for PAH.

Topics: Animals; Arterial Pressure; Arterioles; Endothelin-1; Familial Primary Pulmonary Hypertension; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Pulmonary Artery; Quinolines; Rats; Rats, Wistar; Transforming Growth Factor beta1; Urea; Urotensins

Right ventricular (RV) function is the most important determinant of morbidity and mortality in pulmonary arterial hypertension (PAH). Endothelin (ET)-1 receptor antagonists (ERAs) are approved therapies for PAH. It is not known whether ERAs have effects on the RV, in addition to their vasodilating/antiproliferative effects in pulmonary arteries.. We hypothesized that the ET axis is upregulated in RV hypertrophy (RVH) and that ERAs have direct effects on the RV myocardium.. RV myocardial samples from 34 patients with RVH were compared with 16 nonhypertrophied RV samples, and from rats with normal RV versus RVH attributable to PAH. Confocal immunohistochemistry showed that RVH myocardial ET type A (but not type B) receptor and ET-1 protein levels were increased compared with the nonhypertrophied RVs and positively correlated with the degree of RVH (RV thickness/body surface area; r(2)=0.838 and r(2)=0.818, respectively; P<0.01). These results were recapitulated in the rat model. In modified Langendorff perfusions, ERAs (BQ-123 and bosentan 10(-7,-6,-5) mol/L) decreased contractility in the hypertrophied, but not normal RV, in a dose-dependent manner (P<0.01).. Patients and rats with PAH have an upregulation of the myocardial ET axis in RVH. This might be a compensatory mechanism to preserve RV contractility, as the afterload increases. ERAs use might potentially worsen RV function, and this could explain some of the peripheral edema noted clinically with these agents. Further studies are required to evaluate the effects of ERAs on the RV in patients with RVH and PAH.

Topics: Adolescent; Adult; Animals; Child; Child, Preschool; Endothelin-1; Endothelins; Female; Humans; Hypertrophy, Right Ventricular; Infant; Male; Middle Aged; Prospective Studies; Rats; Receptor, Endothelin A; Up-Regulation; Ventricular Function, Right; Young Adult

Pulmonary arterial hypertension (PAH) is a fatal disease for which no cure is yet available. The leading cause of death in PAH is right ventricular (RV) failure. Previously, the TNF receptor superfamily member fibroblast growth factor-inducible molecule 14 (Fn14) has been associated with different fibrotic diseases. However, so far there is no study demonstrating a causal role for endogenous Fn14 signaling in RV or LV heart disease. The purpose of this study was to determine whether global ablation of Fn14 prevents RV fibrosis and remodeling improving heart function. Here, we provide evidence for a causative role of Fn14 in pulmonary artery banding (PAB)-induced RV fibrosis and dysfunction in mice. Fn14 expression was increased in the RV after PAB. Mice lacking Fn14 (Fn14(-/-)) displayed substantially reduced RV fibrosis and dysfunction following PAB compared to wild-type littermates. Cell culture experiments demonstrated that activation of Fn14 induces collagen expression via RhoA-dependent nuclear translocation of myocardin-related transcription factor-A (MRTF-A)/MAL. Furthermore, activation of Fn14 in vitro caused fibroblast proliferation and myofibroblast differentiation, which corresponds to suppression of PAB-induced RV fibrosis in Fn14(-/-) mice. Moreover, our findings suggest that Fn14 expression is regulated by endothelin-1 (ET-1) in cardiac fibroblasts. We conclude that Fn14 is an endogenous key regulator in cardiac fibrosis and suggest this receptor as potential new target for therapeutic interventions in heart failure.

Topics: Animals; Apoptosis Regulatory Proteins; Blotting, Western; Cell Differentiation; Cell Proliferation; Collagen; Cytokine TWEAK; Endothelin-1; Familial Primary Pulmonary Hypertension; Fibrosis; Fluorescent Antibody Technique; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Membrane Proteins; Mice; Mice, Knockout; Myocardium; Myofibroblasts; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Receptors, Tumor Necrosis Factor; Signal Transduction; Trans-Activators; Transcription Factors; Tumor Necrosis Factors; TWEAK Receptor; Up-Regulation; Ventricular Dysfunction, Right

Topics: Animals; Endothelin-1; Endothelins; Female; Humans; Hypertrophy, Right Ventricular; Male; Receptor, Endothelin A; Up-Regulation; Ventricular Function, Right

Lysophosphatidic acid (LPA) is a bioactive lipid molecule produced by the plasma lysophospholipase D enzyme autotaxin that is present at ≥100 nmol/L in plasma. Local administration of LPA promotes systemic arterial remodeling in rodents. To determine whether LPA contributes to remodeling of the pulmonary vasculature, we examined responses in mice with alterations in LPA signaling and metabolism.. Enpp2(+/-) mice, which are heterozygous for the autotaxin-encoding gene and which have reduced expression of autotaxin/lysophospholipase D and approximately half normal plasma LPA, were hyperresponsive to hypoxia-induced vasoconstriction and remodeling, as evidenced by the development of higher right ventricular (RV) systolic pressure, greater decline in peak flow velocity across the pulmonary valve, and a higher percentage of muscularized arterioles. Mice lacking LPA(1) and LPA(2), 2 LPA receptors abundantly expressed in the vasculature, also had enhanced hypoxia-induced pulmonary remodeling. With age, Lpar1(-/-)2(-/-) mice spontaneously developed elevated RV systolic pressure and RV hypertrophy that was not observed in Lpar1(-/-) mice or Lpar2(-/-) mice. Expression of endothelin-1, a potent vasoconstrictor, was elevated in lungs of Lpar1(-/-)2(-/-) mice, and expression of endothelin(B) receptor, which promotes vasodilation and clears endothelin, was reduced in Enpp2(+/-) and Lpar1(-/-)2(-/-) mice.. Our findings indicate that LPA may negatively regulate pulmonary vascular pressure through LPA(1) and LPA(2) receptors and that in the absence of LPA signaling, upregulation in the endothelin system favors remodeling.

Topics: Animals; Blood Pressure; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Lysophospholipids; Mice; Mice, Inbred BALB C; Mice, Knockout; Phosphoric Diester Hydrolases; Pulmonary Artery; Receptors, Lysophosphatidic Acid; Signal Transduction

We investigated the safety and feasibility of intratracheal administration of autologous bone marrow-derived mononuclear cells (ABM-MNCs) and observed the effects in a canine model of pulmonary hypertension (PH).. The PH model was induced by intravenous injection of 3mg/kg dehydromonocrotaline (DMCT) via the right atrium. Two weeks after DMCT administration, the animals received 4 different treatments (n=10 in each group): (I) negative control group; (II): ABM-MNCs group; (III) PH group; (IV) PH+ABM-MNCs group. Six weeks after injection of cells (10⁷), the hemodynamic data were significantly improved in group IV compared with group III (P<0.05). The ratio of right ventricular weight to left ventricular plus septal weight was significantly decreased in group IV compared with group III (P<0.05). The mRNA levels of vascular endothelial growth factor, preproendothelin-1, interleukin-6 and tumor necrosis factor-α were significantly improved in group IV compared with group III (P<0.05). The immunofluorescence result showed that 6 weeks after administration ABM-MNCs could differentiate into pulmonary vascular endothelial cells.. Six weeks after intratracheal administration, ABM-MNCs significantly improved the impairment caused by DMCT in a canine model of PH (ie, decreased pulmonary arteriolar narrowing, alveolar septum thickening and right ventricular hypertrophy, enhanced angiogenesis) and this provides a firm foundation for a clinical trial.

Topics: Animals; Bone Marrow Transplantation; Cell Differentiation; Cell Separation; Cell Tracking; Disease Models, Animal; Dogs; Endothelial Cells; Endothelin-1; Flow Cytometry; Fluorescent Antibody Technique; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Interleukin-6; Monocrotaline; Neovascularization, Physiologic; Pulmonary Artery; RNA, Messenger; Stem Cell Transplantation; Time Factors; Transplantation, Autologous; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A; Ventricular Function, Right

Chronic right ventricular (RV) pressure overload results in pathologic RV hypertrophy and diminished RV function. Although aortic constriction has been shown to improve systolic function in acute RV failure, its effect on RV responses to chronic pressure overload is unknown.. Adjustable vascular banding devices were placed on the main pulmonary artery and descending aorta. In 5 animals (sham group), neither band was inflated. In 9 animals (PAB group), only the pulmonary arterial band was inflated, with adjustments on a weekly basis to generate systemic or suprasystemic RV pressure at 28 days. In 9 animals, both pulmonary arterial and aortic devices were inflated (PAB + AO group), the pulmonary arterial band as for the PAB group and the aortic band adjusted to increase proximal systolic blood pressure by approximately 20 mm Hg. Effects on the functional performance were assessed 5 weeks after surgery by conductance catheters, followed by histologic and molecular assessment.. Contractile performance was significantly improved in the PAB + AO group versus the PAB group for both ventricles. Relative to sham-operated animals, both banding groups showed significant differences in myocardial histologic and molecular responses. Relative to the PAB group, the PAB + AO group showed significantly decreased RV cardiomyocyte diameter, decreased RV collagen content, and reduced RV expression of endothelin receptor type B, matrix metalloproteinase 9, and transforming growth factor β genes.. Aortic constriction in an experimental model of chronic RV pressure overload not only resulted in improved biventricular systolic function but also improved myocardial remodeling. These data suggest that chronically increased left ventricular afterload leads to a more physiologically hypertrophic response in the pressure-overloaded RV.

Topics: Animals; Aorta; Arterial Pressure; Chronic Disease; Collagen; Collagenases; Connective Tissue Growth Factor; Constriction; Disease Models, Animal; Endothelin-1; Familial Primary Pulmonary Hypertension; Heart Failure; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Myocardial Contraction; Myocardium; Pulmonary Artery; Rabbits; Receptors, Endothelin; Recovery of Function; Time Factors; Transforming Growth Factor beta; Ventricular Function, Left; Ventricular Function, Right; Ventricular Pressure; Ventricular Remodeling

Right ventricular hypertrophy (RVH) and right ventricular (RV) contractile dysfunction are major determinants of prognosis in pulmonary arterial hypertension (PAH) and PAH remains a severe disease. Recently, direct interruption of left ventricular hypertrophy has been suggested to decrease the risk of left-sided heart failure. Hexamethylene bis-acetamide inducible protein 1 (HEXIM1) is a negative regulator of positive transcription elongation factor b (P-TEFb), which activates RNA polymerase II (RNAPII)-dependent transcription and whose activation is strongly associated with left ventricular hypertrophy. We hypothesized that during the progression of PAH, increased P-TEFb activity might also play a role in RVH, and that HEXIM1 might have a preventive role against such process. We revealed that, in the mouse heart, HEXIM1 is highly expressed in the early postnatal period and its expression is gradually decreased, and that prostaglandin I(2), a therapeutic drug for PAH, increases HEXIM1 levels in cardiomyocytes. These results suggest that HEXIM1 might possess negative effect on cardiomyocyte growth and take part in cardiomyocyte regulation in RV. Using adenovirus-mediated gene delivery to cultured rat cardiomyocytes, we revealed that overexpression of HEXIM1 prevents endothelin-1-induced phosphorylation of RNAPII, cardiomyocyte hypertrophy, and mRNA expression of hypertrophic genes, whereas a HEXIM1 mutant lacking central basic region, which diminishes P-TEFb-suppressing activity, could not. Moreover, we created cardiomyocyte-specific HEXIM1 transgenic mice and revealed that HEXIM1 ameliorates RVH and prevents RV dilatation in hypoxia-induced PAH model. Taken together, these findings indicate that cardiomyocyte-specific overexpression of HEXIM1 inhibits progression to RVH under chronic hypoxia, most possibly via inhibition of P-TEFb-mediated enlargement of cardiomyocytes. We conclude that P-TEFb/HEXIM1-dependent transcriptional regulation may play a pathophysiological role in RVH and be a novel therapeutic target for mitigating RVH in PAH.

Topics: Animals; Disease Progression; Endothelin-1; Gene Expression; Gene Expression Regulation; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Mice; Mice, Transgenic; Myocytes, Cardiac; Organ Specificity; Positive Transcriptional Elongation Factor B; Rats; RNA-Binding Proteins; Transcription Factors

Maladaptive right ventricular (RV) hypertrophic responses lead to RV dysfunction and failure in patients with pulmonary arterial hypertension, but the mechanisms responsible for these changes are not well understood. The objective of this study was to evaluate the effect of treatment with bosentan on RV hypertrophy (RVH), fibrosis and expression of protein kinase C (PKC) isoforms in the RV of rats exposed to chronic hypoxia.. Adult Sprague-Dawley rats were housed in normoxia or hypoxia (FIO(2) = 10%) and administered vehicle or 100 mg/kg/day bosentan. After 3 weeks, echocardiographic and hemodynamic assessment was performed. PKC, procollagen-1 and collagen expression levels were assessed using immunoblot or colorimetric assay.. RV systolic pressure (RVSP) and RVH were higher in hypoxic compared with normoxic animals (RVSP: 72 ± 4 vs 25 ± 2 mm Hg, p < 0.05; RVH: 1.2 ± 0.06 vs 0.5 ± 0.03 mg/g body weight, p < 0.05). Bosentan had no effect on RVSP or mass in normoxic animals, but did attenuate RVH in hypoxic animals (hypoxic/vehicle: 1.2 ± 0.06; hypoxic/bosentan: 1.0 ± 0.05 mg/g body weight; p < 0.05). Hypoxia increased RV procollagen-1, and total collagen expression, effects that were attenuated by bosentan treatment. Hypoxia increased RV total and cytosolic PKC-δ protein expression, but had no effect on PKC-α or -ε isoforms. Administration with bosentan did not affect total PKC-δ protein expression. However, animals treated with bosentan had an increase in membranous PKC-δ when exposed to hypoxia.. Bosentan inhibits RVH and RV collagen expression in rats exposed to chronic hypoxia, possibly via alteration of PKC-δ activity.

Topics: Animals; Antihypertensive Agents; Bosentan; Collagen; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Fibrosis; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Myocardium; Protein Isoforms; Protein Kinase C; Rats; Rats, Sprague-Dawley; Signal Transduction; Sulfonamides; Ventricular Dysfunction, Right

Intermittent hypoxia (IH) resulting from sleep apnea causes both systemic and pulmonary hypertension. Enhanced endothelin-1 (ET-1)-induced vasoconstrictor reactivity is thought to play a central role in the systemic hypertensive response to IH. However, whether IH similarly increases pulmonary vasoreactivity and the signaling mechanisms involved are unknown. The objective of the present study was to test the hypothesis that IH augments ET-1-induced pulmonary vasoconstrictor reactivity through a PKCβ-dependent signaling pathway. Responses to ET-1 were assessed in endothelium-disrupted, pressurized pulmonary arteries (∼150 μm inner diameter) from eucapnic-IH [(E-IH) 3 min cycles, 5% O(2)-5% CO(2)/air flush, 7 h/day; 4 wk] and sham (air-cycled) rats. Arteries were loaded with fura-2 AM to monitor vascular smooth muscle (VSM) intracellular Ca(2+) concentration ([Ca(2+)](i)). E-IH increased vasoconstrictor reactivity without altering Ca(2+) responses, suggestive of myofilament Ca(2+) sensitization. Consistent with our hypothesis, inhibitors of both PKCα/β (myr-PKC) and PKCβ (LY-333-531) selectively decreased vasoconstriction to ET-1 in arteries from E-IH rats and normalized responses between groups, whereas Rho kinase (fasudil) and PKCδ (rottlerin) inhibition were without effect. Although E-IH did not alter arterial PKCα/β mRNA or protein expression, E-IH increased basal PKCβI/II membrane localization and caused ET-1-induced translocation of these isoforms away from the membrane fraction. We conclude that E-IH augments pulmonary vasoconstrictor reactivity to ET-1 through a novel PKCβ-dependent mechanism that is independent of altered PKC expression. These findings provide new insights into signaling mechanisms that contribute to vasoconstriction in the hypertensive pulmonary circulation.

Topics: Animals; Blood Gas Analysis; Blotting, Western; Calcium; Endothelin-1; Fura-2; Gene Expression Regulation; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Muscle, Smooth, Vascular; Protein Kinase C; Protein Kinase C beta; Protein Kinase C-alpha; Protein Kinase Inhibitors; Pulmonary Artery; Rats; Rats, Wistar; rho-Associated Kinases; RNA, Messenger; Signal Transduction; Vasoconstriction; Vasoconstrictor Agents

1. The aim of the present study was to investigate the in vivo effects of vasonatrin peptide (VNP) on hypoxia-induced pulmonary hypertension (HPH). 2. The HPH model was developed by subjecting rats to hypobaric hypoxia. The HPH rats were then treated with either VNP (50 microg/kg per day, i.p.) or saline (0.5 mL, i.p.) every day for 7 days. Haemodynamic indices, right ventricular hypertrophy (RVH) and remodelling of the pulmonary arteries were evaluated. In addition, plasma levels of atrial natriuretic peptide (ANP), endothelin (ET)-1 and angiotensin II (AngII) were determined, as was natriuretic peptide receptor-C (NPR-C) mRNA expression in the right ventricle. 3. Hypobaric hypoxia induced severe HPH compared with the normoxic control group. Treatment of HPH rats with VNP for 1 week significantly reduced mean pulmonary arterial pressure, pulmonary vascular resistance, RVH and muscularization of the pulmonary arteries, although pulmonary blood flow was increased in this group. In addition, significantly lower levels of plasma ET-1 and AngII and cardiac NPR-C mRNA expression were observed in VNP-treated compared with saline-treated HPH rats, whereas higher plasma concentrations of ANP were found in the former group. Acute intravenous administration of 50 microg/kg VNP significantly ameliorated pulmonary haemodynamics in HPH rats. 4. Taken together, the date indicate that VNP has certain preventative and therapeutic effects against HPH.

Topics: Angiotensin II; Animals; Antihypertensive Agents; Atmospheric Pressure; Atrial Natriuretic Factor; Disease Models, Animal; Endothelin-1; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptors, Atrial Natriuretic Factor

We hypothesised that the potential protective effects of endothelial ET(B) are important in limiting pulmonary vascular muscularisation, vasoconstriction and the development of pulmonary arterial hypertension in response to hypoxia.. EC-specific ET(B) knockout mice (EC ET(B)(-/-)) and control mice (ET(B)(f/f)) were subjected to hypobaric hypoxic (10% FiO2) or normoxic conditions for 14 days before assessment of right ventricular pressure and pulmonary vascular morphology and function.. During normoxia, no difference in right ventricular pressure was detected between EC ET(B)(-/-) (23.7 +/- 1.7 mm Hg) and ET(B)(f/f) mice (20.2 +/- 1.5 mm Hg). Hypoxia induced an exaggerated increase in right ventricular pressure in EC ET(B)(-/-) mice (34.4 +/- 1.2 mm Hg vs. 24.6 +/- 1.4 mm Hg), accompanied by an increase in right ventricular mass. No effect was observed in ET(B)(f/f) mice. Endothelin-1 constricted pulmonary arteries from both groups, although maximum response was similar irrespective of inspired oxygen or genotype. Hypoxia increased the percentage of muscularised vessels in both groups of mice, but the percentage increase was significantly greater in EC ET(B)(-/-) mice.. The potential protective effects of endothelial ET(B) are important in limiting pulmonary vascular muscularisation and the development of pulmonary arterial hypertension in response to hypoxia.

Topics: Animals; Blood Pressure; Disease Models, Animal; Endothelin-1; Endothelium, Vascular; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Pulmonary Artery; Receptor, Endothelin B; Vasoconstriction; Ventricular Pressure

Pulmonary hypertension (PH) is characterized by elevated pulmonary artery pressure (PAP), pulmonary vascular remodeling and right ventricular hypertrophy, which are mainly due to endothelial dysfunction. Electro-acupuncture has shown beneficial effects on cardiovascular homeostasis, but little evidence has been obtained on pulmonary effects. The goal of the present study was to investigate whether electro-acupuncture on bladder-13 and -15 points can protect against chronic hypoxia-induced PH by regulating endothelium-derived endothelin (ET)-1 and endothelial nitric oxide synthase (eNOS). Male Wistar rats were exposed to hypoxia to induce PH. Hemodynamic analysis revealed that mean PAP was similar under normoxic conditions. Chronic hypoxia increased mean PAP to 37 +/- 3 mmHg, and electro-acupuncture attenuated it to 29 +/- 3 mmHg. Absolute right ventricular weight was ameliorated by electro-acupuncture from 0.288 +/- 0.048 g to 0.228 +/- 0.029 g under hypoxic conditions. Hypoxia-induced right ventricular hypertrophy index decreased from 0.477 +/- 0.069 to 0.378 +/- 0.053 with electro-acupuncture treatment. Histological examination revealed that hypoxic rats showed increased medial pulmonary artery wall thickness as well as muscularization. However, these alternations by chronic hypoxia were attenuated by electro-acupuncture. There was no difference in eNOS or ET-1 between groups under normoxic conditions. Electro-acupuncture treatment significantly improved the circulating eNOS concentration (365.36 +/- 31.51 pg/mL) compared with only hypoxia exposure (247.60 +/- 30.64 pg/mL). In lung homogenate, levels of eNOS under hypoxia increased from 684.96 +/- 117.90 to 869.86 +/- 197.61 pg/mg by electro-acupuncture treatment. Levels of ET-1 changed oppositely to eNOS in response to electro-acupuncture (ET-1 in plasma, 29.44 +/- 2.09 versus 20.70 +/- 2.37 pg/mL; ET-1 in lung homogenate, 120.51 +/- 3.03 versus 110.60 +/- 4.04 pg/mg). In conclusion, these results indicated that treatment with electro-acupuncture can protect against hypoxia-induced PH, possibly by regulating the balance of endothelium-derived vasoconstrictors and vasodilators.

Topics: Animals; Electroacupuncture; Endothelin-1; Endothelium; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Lung; Nitric Oxide Synthase Type III; Rats; Rats, Wistar; Tissue Extracts

Pulmonary hypertension is a kind of disease associated with a very high rate of mortality, and there are not many effective drugs for the treatment. Today, endothelin (ET)-1 receptor antagonists were proved to be effective in the treatment of pulmonary hypertension. Aiming at developing new endothelin-A receptor (ETA) antagonist for treatment of pulmonary hypertension, di-n-butylaminocarbamyl-L-leucyl-D-tryptophanyl-D-4-chloro-Phe, named GF063, was synthesized at base of selective ETA receptor antagonist BQ485 and selected for the further pharmacological characterization. The preliminary pharmacodynamics of GF063 was evaluated by radioligand receptor binding assay and test of antivasoconstriction effects in vitro and in vivo. The integrative pharmacodynamics was evaluated in hypoxia-induced rat pulmonary hypertension. In vitro, GF063 bound to ETA receptor with 100,000-fold higher affinity than to ETB receptor. GF063 concentration dependently inhibited contraction of isolated rat aortic ring induced by ET-1 and shifted the cumulative concentration-contraction response curve to right with no change in the maximal response. In vivo, GF063 inhibited the increase of mean systemic arterial pressure induced by ET-1 in anesthetized rat. In hypoxia-induced rat pulmonary hypertension model, pretreatment with GF063 (40 mg/kg, s.c.) significantly decreased pulmonary artery pressure and right ventricular hypertrophy, also significantly inhibited the increase of ET-1 level in lung, improved hemodynamics, and alleviated the wall thickness of pulmonary vessels. This study indicated that GF063, as a selective ETA receptor antagonist, could inhibit vasoconstriction effects in vivo and in vitro, could prevent pulmonary hypertension induced by hypoxia, and may have great potential to be developed as a new drug of antipulmonary hypertension.

Topics: Animals; Aorta, Thoracic; Blood Pressure; Dose-Response Relationship, Drug; Endothelin A Receptor Antagonists; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Lung; Male; Oligopeptides; Pulmonary Artery; Rats; Rats, Wistar; Vasoconstriction

Chronic pulmonary hypertension in infancy and childhood is characterized by a fixed and progressive increase in pulmonary arterial pressure and resistance, pulmonary arterial remodeling, and right ventricular hypertrophy and systolic dysfunction. These abnormalities are replicated in neonatal rats chronically exposed to hypoxia from birth in which increased activity of Rho-kinase (ROCK) is critical to injury, as evidenced by preventive effects of ROCK inhibitors. Our objective in the present study was to examine the reversing effects of a late or rescue approach to treatment with a ROCK inhibitor on the pulmonary and cardiac manifestations of established chronic hypoxic pulmonary hypertension. Rat pups were exposed to air or hypoxia (13% O(2)) from postnatal day 1 and were treated with Y-27632 (15 mg/kg) or saline vehicle by twice daily subcutaneous injection commencing on day 14, for up to 7 days. Treatment with Y-27632 significantly attenuated right ventricular hypertrophy, reversed arterial wall remodeling, and completely normalized right ventricular systolic function in hypoxia-exposed animals. Reversal of arterial wall remodeling was accompanied by increased apoptosis and attenuated content of endothelin (ET)-1 and ET(A) receptors. Treatment of primary cultured juvenile rat pulmonary artery smooth muscle cells with Y-27632 attenuated serum-stimulated ROCK activity and proliferation and increased apoptosis. Smooth muscle apoptosis was also induced by short interfering RNA-mediated knockdown of ROCK-II, but not of ROCK-I. We conclude that sustained rescue treatment with a ROCK inhibitor reversed both the hemodynamic and structural abnormalities of chronic hypoxic pulmonary hypertension in juvenile rats and normalized right ventricular systolic function. Attenuated expression and activity of ET-1 and its A-type receptor on pulmonary arterial smooth muscle was a likely contributor to the stimulatory effects of ROCK inhibition on apoptosis. In addition, our data suggest that ROCK-II may be dominant in enhancing survival of pulmonary arterial smooth muscle.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Age Factors; Aging; Amides; Animals; Apoptosis; Cell Proliferation; Cells, Cultured; Chronic Disease; Disease Models, Animal; Endothelin-1; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Injections, Subcutaneous; Muscle, Smooth, Vascular; Myocardium; Protein Kinase Inhibitors; Pulmonary Artery; Pyridines; Rats; Receptor, Endothelin A; rho-Associated Kinases; RNA Interference; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

We investigated the endogenous production of apelin and the cardiac and pulmonary effects of its chronic administration in monocrotaline (MCT)-induced pulmonary hypertension (PH). Male Wistar rats were injected with MCT (60 mg/kg sc) or vehicle (day 0). One week later, these animals were randomly treated during 17 days with pyroglutamylated apelin-13 (Pyr-AP13; 200 microg*kg(-1)*day(-1) ip) or a similar volume of saline, resulting in four groups: sham (n = 11), sham-AP (n = 11), MCT (n = 16), and MCT-AP (n = 13). On day 25, right ventricular (RV) and left ventricular (LV) hemodynamic and morphometric parameters were assessed. Tissue and plasma samples were collected for histological and molecular analysis. When compared with sham, the MCT group presented a significant increase of RV mass (166 +/- 38%), diameter of cardiomyocyte (40 +/- 10%), myocardial fibrosis (95 +/- 20%), peak systolic pressure (99 +/- 22%), peak rate of ventricular pressure rise (dP/dt(max); 74 +/- 24%), peak rate of ventricular pressure decline (dP/dt(min); 73 +/- 19%), and time constant tau (55 +/- 16%). In these animals, RV expression of apelin (-73 +/- 10%) and its receptor APJ (-61 +/- 20%) was downregulated, whereas mRNA expression of type B natriuretic peptide (9,606 +/- 713%), angiotensinogen (191 +/- 147%), endothelin-1 (RV, 497 +/- 156%; and LV, 799 +/- 309%), plasmatic levels of apelin (104 +/- 48%), and angiotensin 1-7 (161 +/- 151%) were increased. Chronic treatment with Pyr-AP13 significantly attenuated or normalized these changes, preventing apelin-APJ mRNA downregulation and PH-induced neurohumoral activation of several vasoconstrictors, which exacerbates apelin-APJ vasodilator effects. Therefore, apelin delayed the progression of RV hypertrophy and diastolic dysfunction. Together, these observations suggest that the apelin-APJ system may play an important role in the pathophysiology of PH, representing a potential therapeutic target since it significantly attenuates RV overload and PH-induced neurohumoral activation.

Topics: Angiotensin I; Animals; Antihypertensive Agents; Apelin; Apelin Receptors; Carrier Proteins; Endothelin-1; Gene Expression Profiling; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Intercellular Signaling Peptides and Proteins; Male; Monocrotaline; Myocardium; Peptide Fragments; Rats; Rats, Wistar; Receptors, G-Protein-Coupled; RNA, Messenger; Ventricular Function, Right

We investigated whether the chronic treatment with raloxifene, a selective estrogen receptor modulator, prevents the development of monocrotaline-induced pulmonary hypertension in ovary-intact and ovariectomized female rats. Four weeks after a single subcutaneous injection of monocrotaline (60 mg/kg), right ventricular systolic pressure, right ventricle-to-left ventricle plus septal weight ratio, pulmonary arterial medial thickening and endothelin-1 levels in right ventricular tissue increased significantly in both female rats, compared with saline-treated control rats. These monocrotaline-induced alterations were much greater in ovariectomized rats than the changes in intact females. Daily oral administration of raloxifene (10 mg/kg/day for 4 weeks) significantly attenuated the increase in right ventricular systolic pressure to the same levels in both groups of animals, but raloxifene suppressed the increases in right ventricle-to-left ventricle plus septal weight ratio and pulmonary arterial medial thickness more efficiently in ovariectomized females than the case with intact females. In addition, raloxifene completely suppressed the increase in right ventricular endothelin-1 levels in ovariectomized rats, but not in intact females. These data suggest that chronic treatment with raloxifene effectively prevents the development of monocrotaline-induced pulmonary hypertension in ovariectomized female rats than in intact females, at least in part, by suppressing right ventricular endothelin-1 overproduction.

Topics: Animals; Blood Pressure; Body Weight; Endothelin-1; Female; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Monocrotaline; Organ Size; Ovariectomy; Pulmonary Artery; Raloxifene Hydrochloride; Rats; Rats, Sprague-Dawley; Receptors, Estrogen; Substrate Specificity; Time Factors; Ventricular Dysfunction, Right

Pulmonary hypertension is a kind of disease associated with a very high rate of mortality. There are not many effective drugs for the treatment of pulmonary hypertension. Treatment with ET-1 receptor antagonists was proved to be effective in the treatment of pulmonary hypertension. Aiming at developing new endothelin A receptor (ET(A)) antagonist for treatment of pulmonary hypertension, 242 peptide compounds were synthesized by structural optimization of a selective ET(A) receptor antagonist BQ-123. Among these, -azabicyclo[3,2,1]octane-1-yl-l-Leucyl-d-tryptophanyl-d-4-Cl-phenylalanine, named ETP-508, was selected for further harmacological characterization.. Radioligand binding assay was performed to study the binding affinity of ETP-508 for ET(A) and ET(B) receptors. The biological activity of ETP-508 was evaluated in isolated rat aortic ring experiment and in systemic arterial pressure experiment. In addition, hypotensive effect of ETP-508 was investigated on hypoxia-induced pulmonary hypertension.. ETP-508 binds to endothelin ET(A) receptor with >10,000-fold higher affinity than to endothelin B receptor in rat lung tissue preparation. ETP-508 inhibited endothelin-1 (ET-1)-induced contraction of isolated rat aortic ring and shifted the cumulative concentration-contraction response curve to ET-1 to right with no change in the maximal response. In vivo, ETP-508 inhibited the increased effect of ET-1 on mean systemic arterial pressure. Pre-treatment with ETP-508 by intravenous infusion significantly inhibited chronic hypoxia-induced pulmonary hypertension and right ventricular hypertrophy. ETP-508 also significantly inhibited the increase in lung ET-1 expression level, hemoglobin, red-cell count and red-cell hematocrit as induced by hypoxia. Furthermore, ETP-508 partially reversed pre-established pulmonary hypertension and right ventricle hypertrophy by chronic hypoxia.. These results indicated that ETP-508 is a novel highly selective ET(A) receptor antagonist and may have a great potential to be developed as a drug of anti-pulmonary hypertension.

Topics: Animals; Aorta, Thoracic; Azabicyclo Compounds; Azepines; Blood Pressure; Chronic Disease; Dose-Response Relationship, Drug; Endothelin A Receptor Antagonists; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Lung; Male; Molecular Structure; Oligopeptides; Peptides, Cyclic; Rats; Rats, Wistar; Time Factors; Vasoconstriction

Pulmonary hypertension (PH) is a disease of unknown etiology that ultimately causes right ventricle heart failure with a lethal outcome. An increase in circulating endothelin (ET)-1 levels may contribute to disease progression. This study aimed to examine the possible effects of an orally active ET receptor antagonist, sulfisoxazole (SFX), for the rescue of PH, right ventricular hypertrophy, and eventual right ventricular failure. PH rats (single injection of monocrotaline [MCT]) were treated with an ET antagonist, SFX, an orally active sulfonamide antibody. Effects of SFX on PH rats were assessed in terms of survival rate, pulmonary artery blood pressure (PABP), autonomic nerve activity, and atrial natriuretic peptide (ANP) concentration in right ventricular myocytes and plasma. SFX did not change systemic blood pressure, however, it significantly suppressed the elevation of PABP. SFX maintained the derangement of autonomic nerve control, blunted an increase in ANP in myocytes and plasma, and significantly improved survival in right heart failure and/or related organs dysfunction in PH rats. The ET antagonistic action of the antimicrobial agent, SFX, was experimentally confirmed for treatment of PH in rats.

Topics: Administration, Oral; Animals; Anti-Infective Agents; Atrial Natriuretic Factor; Blood Pressure; Disease Models, Animal; Electrocardiography; Endothelin Receptor Antagonists; Endothelin-1; Heart Rate; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Myocytes, Cardiac; Pulmonary Artery; Rats; Rats, Wistar; Receptors, Endothelin; Sulfisoxazole; Sympathetic Nervous System

Cyclooxygenase-2 (COX-2) is upregulated in pulmonary artery smooth muscle cells (PASMCs) during hypoxia and may play a protective role in the response of the lung to hypoxia. Selective COX-2 inhibition may have detrimental pulmonary vascular consequences during hypoxia.. To investigate the role of COX-2 in the pulmonary vascular response to hypoxia, we subjected wild-type and COX-2-deficient mice to a model of chronic normobaric hypoxia. COX-2-null mice developed severe pulmonary hypertension with exaggerated elevation of right ventricular systolic pressure, significant right ventricular hypertrophy, and striking vascular remodeling after hypoxia. Pulmonary vascular remodeling in COX-2-deficient mice was characterized by PASMC hypertrophy but not increased proliferation. Furthermore, COX-2-deficient mice had significant upregulation of the endothelin-1 receptor (ET(A)) in the lung after hypoxia. Similarly, selective pharmacological inhibition of COX-2 in wild-type mice exacerbated hypoxia-induced pulmonary hypertension and resulted in PASMC hypertrophy and increased ET(A) receptor expression in pulmonary arterioles. The absence of COX-2 in vascular smooth muscle cells during hypoxia in vitro augmented traction forces and enhanced contractility of an extracellular matrix. Treatment of COX-2-deficient PASMCs with iloprost, a prostaglandin I(2) analog, and prostaglandin E(2) abrogated the potent contractile response to hypoxia and restored the wild-type phenotype.. Our findings reveal that hypoxia-induced pulmonary hypertension and vascular remodeling are exacerbated in the absence of COX-2 with enhanced ET(A) receptor expression and increased PASMC hypertrophy. COX-2-deficient PASMCs have a maladaptive response to hypoxia manifested by exaggerated contractility, which may be rescued by either COX-2-derived prostaglandin I(2) or prostaglandin E(2).

Topics: Animals; Blood Pressure; Cells, Cultured; Chronic Disease; Collagen; Cyclooxygenase 2; Dinoprostone; Endothelin-1; Gels; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Iloprost; Mice; Mice, Mutant Strains; Muscle Contraction; Muscle, Smooth, Vascular; Pulmonary Artery; Receptor, Endothelin A; Traction; Vasoconstriction; Vasodilator Agents

Although one of the common characteristics of pulmonary hypertension is abnormal sustained vasoconstriction, the signaling pathways that mediate this heightened pulmonary vascular response are still not well defined. Protein kinase C (PKC) and Rho-kinase are regulators of smooth muscle contraction induced by G protein-coupled receptor agonists including endothelin-1 (ET-1), which has been implicated as a signaling pathway in pulmonary hypertension. Toward this end, it was hypothesized that both Rho-kinase and PKC mediate the pulmonary vascular response to ET-1 in hypertensive pulmonary arterial smooth muscle, and therefore, the purpose of this study was to determine the role of PKC and Rho-kinase signaling in ET-1-induced vasoconstriction in both normotensive (Sprague-Dawley) and hypertensive (Fawn-Hooded) rat pulmonary arterial smooth muscle. Results indicate that ET-1 caused greater vasoconstriction in hypertensive pulmonary arteries compared with the normal vessels, and treatment with the PKC antagonists chelerythrine, rottlerin, and Gö 6983 inhibited the vasoconstrictor response to ET-1 in the hypertensive vessels. In addition, the specific Rho-kinase inhibitor Y-27632 significantly attenuated the effect of ET-1 in both normotensive and hypertensive phenotypes, with greater inhibition occurring in the hypertensive arteries. Furthermore, Western blot analysis revealed that ET-1 increased RhoA expression in both normotensive and hypertensive pulmonary arteries, with expression being greater in the hypertensive state. These results suggest that both PKC and Rho/Rho-kinase mediate the heightened pulmonary vascular response to ET-1 in hypertensive pulmonary arterial smooth muscle.

Topics: Amides; Animals; Blotting, Western; Carbazoles; Endothelin-1; Enzyme Inhibitors; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Indoles; Intracellular Signaling Peptides and Proteins; Male; Maleimides; Muscle, Smooth, Vascular; Potassium Chloride; Protein Kinase C; Protein Serine-Threonine Kinases; Pulmonary Artery; Pyridines; Rats; Rats, Sprague-Dawley; rho-Associated Kinases; Species Specificity; Vasoconstriction

Neuronal function and innervation density is regulated by target organ-derived neurotrophic factors. Although cardiac hypertrophy drastically alternates the expression of various growth factors such as endothelin-1, angiotensin II, and leukemia inhibitory factor, little is known about nerve growth factor expression and its effect on the cardiac sympathetic nerves. This study investigated the impact of pressure overload-induced cardiac hypertrophy on the innervation density and cellular function of cardiac sympathetic nerves, including kinetics of norepinephrine synthesis and reuptake, and neuronal gene expression. Right ventricular hypertrophy was induced by monocrotaline treatment in Wistar rats. Newly developed cardiac sympathetic nerves expressing beta(3)-tubulin (axonal marker), GAP43 (growth-associated cone marker), and tyrosine hydroxylase were markedly increased only in the right ventricle, in parallel with nerve growth factor upregulation. However, norepinephrine and dopamine content was paradoxically attenuated, and the protein and kinase activity of tyrosine hydroxylase were markedly downregulated in the right ventricle. The reuptake of [(125)I]-metaiodobenzylguanidine and [(3)H]-norepinephrine were also significantly diminished in the right ventricle, indicating functional downregulation in cardiac sympathetic nerves. Interestingly, we found cardiac sympathetic nerves in hypertrophic right ventricles strongly expressed highly polysialylated neural cell adhesion molecule (PSA-NCAM) (an immature neuron marker) as well as neonatal heart. Taken together, pressure overload induced anatomical sympathetic hyperinnervation but simultaneously caused deterioration of neuronal cellular function. This phenomenon was explained by the rejuvenation of cardiac sympathetic nerves as well as the hypertrophic cardiomyocytes, which also showed the fetal form gene expression.

Topics: Adrenergic Fibers; Animals; Dopamine; Endothelin-1; GAP-43 Protein; Gene Expression Regulation; Heart Failure; Heart Ventricles; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Kinetics; Male; Monocrotaline; Myocytes, Cardiac; Nerve Growth Factor; Neural Cell Adhesion Molecule L1; Norepinephrine; Rats; Rats, Wistar; Sialic Acids; Tubulin; Tyrosine 3-Monooxygenase; Up-Regulation

Topics: Adrenergic Fibers; Angiotensin II; Animals; Calcium; Endothelin-1; Heart Failure; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Mice; Nerve Growth Factor; Rats; Tyrosine 3-Monooxygenase; Vasoconstriction; Ventricular Dysfunction, Right

The endothelin system plays an important role in the development of pulmonary hypertension. Several studies have suggested that interfering with the function of the endothelin system will be helpful in pulmonary hypertension treatment. In the present study, we investigated the preventive and therapeutic effects of sildenafil on pulmonary hypertension in monocrotaline-treated rats. In the preventive study, the level of mean pulmonary arterial pressure, right ventricular divide, left ventricular and septum, small pulmonary arterial morphologic and elastic fiber changes were highly improved in the treated group (P<0.05). The expressions of endothelin-1 A type receptors on small pulmonary arterial hypertension were significantly reduced in the sildenafil-treated group (P<0.05). The ET-1 level in plasma was increased in the sildenafil-treated group, but did not reach significance. Emphysema, interstitial pneumonia were significantly improved in the sildenafil-treated group. The same findings were also observed in the therapeutic study. The present results suggest that sildenafil can prevent and reverse the development of pulmonary hypertension in monocrotaline-treated rats by improving the function of endothelin system in pulmonary arteries.

Topics: Administration, Oral; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Lung Diseases, Interstitial; Male; Monocrotaline; Piperazines; Pulmonary Artery; Pulmonary Emphysema; Purines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Sildenafil Citrate; Sulfones; Time Factors; Vasodilator Agents

Pulmonary hypertension is characterized by high pulmonary blood pressure, vascular remodeling, and right ventricular hypertrophy. Although recent studies suggest that an imbalance between endothelial mediators on pulmonary vasculature may contribute to the development of pulmonary hypertension, the pathogenesis is not fully understood and the treatment of pulmonary hypertension is still unresolved.. The purpose of this study was to investigate whether genistein, a phytoestrogen derived from soybean, would prevent the development of monocrotaline (MCT)-induced pulmonary hypertension in rats. Hemodynamic parameters of catheterized rats and morphological feature of lungs were evaluated among MCT-treated rats receiving or not receiving genistein. Furthermore, examination of expression in endothelial nitric oxide synthase and endothelin-1 peptide level was performed.. Daily supplementation with either genistein (0.2 mg/kg) or vehicle was started 2 days prior to a single-dose injection of MCT (60 mg/kg). On day 28, rats underwent catheterization, and right ventricular hypertrophy and morphological features were assessed. Furthermore, endothelial nitric oxide synthase and endothelin-1 were examined by Western blot analysis and radioimmunoassay, respectively, in homogenated lungs.. In rats that received daily supplementation of genistein, mean pulmonary arterial pressure was significantly reduced, whereas mean systemic arterial pressure and heart rate were unaltered compared with MCT control rats on day 28 after MCT injection. Right ventricular hypertrophy, medial wall thickness of pulmonary arteries corresponding to the terminal bronchioles, and the degree of neo-muscularization of more distal arteries were less severe in genistein-treated rats. Genistein supplementation improved MCT-induced downregulation of expression of endothelial nitric oxide synthase in the lungs. However, endothelin-1 peptide levels did not differ among all groups of lungs.. We conclude that daily supplementation of genistein potently attenuates MCT-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular remodeling in rats. The underlying mechanism responsible for this effect may be partly related to the restoration of a decreased expression of endothelial nitric oxide synthase.

Topics: Animals; Blotting, Western; Down-Regulation; Endothelin-1; Endothelium, Vascular; Enzyme Inhibitors; Genistein; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Lung; Male; Monocrotaline; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Vascular Resistance

Induction of hypercapnia by breathing high concentrations of carbon dioxide (CO(2)) may have beneficial effects on the pulmonary circulation. We tested the hypothesis that exposure to CO(2) would protect against chronic pulmonary hypertension in newborn rats. Atmospheric CO(2) was maintained at <0.5% (normocapnia), 5.5%, or 10% during exposure from birth for 14 days to normoxia (21% O(2)) or moderate hypoxia (13% O(2)). Pulmonary vascular and hemodynamic abnormalities in animals exposed to chronic hypoxia included increased pulmonary arterial resistance, right ventricular hypertrophy and dysfunction, medial thickening of pulmonary resistance arteries, and distal arterial muscularization. Exposure to 10% CO(2) (but not to 5.5% CO(2)) significantly attenuated pulmonary vascular remodeling and increased pulmonary arterial resistance in hypoxia-exposed animals (P < 0.05), whereas both concentrations of CO(2) normalized right ventricular performance. Exposure to 10% CO(2) attenuated increased oxidant stress induced by hypoxia, as quantified by 8-isoprostane content in the lung, and prevented upregulation of endothelin-1, a critical mediator of pulmonary vascular remodeling. We conclude that hypercapnic acidosis has beneficial effects on pulmonary hypertension and vascular remodeling induced by chronic hypoxia, which we speculate derives from antioxidant properties of CO(2) on the lung and consequent modulating effects on the endothelin pathway.

Topics: Animals; Animals, Newborn; Body Weight; Carbon Dioxide; Carboxylic Acids; Chronic Disease; Endothelin Receptor Antagonists; Endothelin-1; Female; Hematocrit; Hypercapnia; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indans; Oxidative Stress; Oxygen; Pregnancy; Pulmonary Artery; Pulmonary Circulation; Rats; Up-Regulation

Endothelin-1 (ET-1) plays a key role in the pathogenesis of pulmonary hypertension. The present study was conducted to examine the effects of a novel compound p-chlorobenzyltetrahydroberberine (CPU 86017) on endothelin-1 system of hypoxia-induced pulmonary hypertension in rats. SD male rats were divided into control, untreated pulmonary hypertension, nifedipine (10 mg/kg p.o.), and CPU 86017 (80, 40, and 20 mg/kg p.o.) groups. The pulmonary hypertension was established by housing the rats in a hypoxic (10 +/- 0.5% oxygen) chamber 8 hours per day for 4 weeks. Hemodynamic and morphologic assessment exhibited a significant increase in the central vein pressure (CVP), right ventricular systolic pressure (RVSP), and pulmonary arteriole remodeling in the pulmonary hypertensive rats, which were improved by CPU 86017 80 and 40 mg/kg administration (P < 0.01). The elevated pulmonary endothelin-1 level and the over-active preproET-1 and iNOS mRNA expression were also decreased significantly (P < 0.01) in CPU 86017 groups. The maladjustment of redox enzyme system in pulmonary hypertension rats was corrected after treatment. We concluded that CPU 86017 improves pulmonary hypertension mainly to suppress the endothelin-1 pathway at the upstream and downstream via calcium antagonism and antioxidative action, then, resulting in a relief in pathogenesis of the disease.

Topics: Animals; Antioxidants; Berberine; Calcium Channel Blockers; Calcium Channels, L-Type; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Male; Malondialdehyde; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Pulmonary Artery; Rats; Rats, Sprague-Dawley

Mechanical factors play a key role in activation of cardiac growth factor response in hemodynamic overload, and both cooperate in myocardial remodeling. The present study was performed to investigate whether a different growth factor response is activated in the right and left ventricles in aortocaval fistula and its effects on regional myocardial adaptation. Relations between regional growth factor expression (angiotensin II, insulin-like growth factor-I, and endothelin-1), myocyte shape changes, and collagen deposition were investigated at mRNA and peptide levels in adult pigs after the creation of an aortocaval fistula distal to the renal arteries (n=15) and in sham-operated animals (n=15). The role of angiotensin II was investigated by the administration of angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonist. In the left ventricle, pure volume overload was accompanied by persistent increase of insulin-like growth factor-I mRNA expression, peptide concentration (2.2-fold versus sham at 3 months, P<0.05), and significant increase of myocyte length (+29% at 3 months, P<0.05). Conversely, the mixed pressure-volume overload faced by the right ventricle resulted in significant regional overexpression of all growth factors investigated (angiotensin II, insulin-like growth factor-I, and endothelin-1), with corresponding increase of myocyte diameter and length and collagen deposition (+117% at 3 months). Collagen accumulation in the right ventricle as well as the increase in right ventricular end-diastolic pressure at the 3-month observation were inhibited by angiotensin II antagonism. The left and right ventricles respond differently to aortocaval fistula, and local growth factor expression is closely related to the regional myocardial adaptation.

Topics: Adaptation, Physiological; Angiotensin II; Animals; Cardiac Volume; Collagen; Endothelin-1; Female; Growth Substances; Heart Ventricles; Hemodynamics; Hypertrophy, Left Ventricular; Hypertrophy, Right Ventricular; Insulin-Like Growth Factor I; Male; RNA, Messenger; Swine

1. The purpose of this study was to investigate whether a membrane-permeable superoxide dismutase mimetic, tempol, added either alone or in combination with the nitric oxide (NO) donor molsidomine, prevents the development of pulmonary hypertension (PH) in chronic hypoxic rats. 2. Chronic hypobaric hypoxia (10% oxygen) for 2 weeks increased the right ventricular systolic pressure (RVSP), right ventricle and lung wet weight. Relaxations evoked by acetylcholine (ACh) and the molsidomine metabolite SIN-1 were impaired in isolated proximal, but not distal pulmonary arteries, from chronic hypoxic rats. 3. Treatment with tempol (86 mg x kg(-1) day(-1) in drinking water) normalized RVSP and reduced right ventricular hypertrophy, while systemic blood pressure, lung and liver weights, and blunted ACh relaxation of pulmonary arteries were unchanged. 4. Treatment with molsidomine (15 mg x kg(-1) day(-1) in drinking water) had the same effects as tempol, except that liver weight was reduced, and potassium and U46619-evoked vasoconstrictions in pulmonary arteries were increased. Combining tempol and molsidomine did not have additional effects compared to tempol alone. ACh relaxation in pulmonary arteries was not normalized by these treatments. 5. The media to lumen diameter ratio of the pulmonary arteries was greater for the hypoxic rats compared to the normoxic rats, and was not reversed by treatment with tempol, molsidomine, or the combination of tempol and molsidomine. 6. We conclude that tempol, like molsidomine, is able to correct RVSP and reduce right ventricular weight in the rat hypoxic model. Functional and structural properties of pulmonary small arteries were little affected. The results support the possibility that superoxide dismutase mimetics may be a useful means for the treatment of PH.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Administration, Oral; Animals; Body Weight; Chronic Disease; Cyclic N-Oxides; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Drug Therapy, Combination; Endothelin-1; Free Radical Scavengers; Heart Rate; Hypertrophy, Right Ventricular; Hypoxia; Male; Molsidomine; Muscle, Smooth, Vascular; Organ Size; Pulmonary Artery; Rats; Rats, Wistar; Spin Labels; Superoxide Dismutase; Vasoconstriction; Vasodilation; Ventricular Pressure

Although activation of the endothelin (ET) system contributes to pulmonary hypertension, modifications of the cardiopulmonary ET system and its responses to chronic ET receptor blockade are not well known. To investigate this, rats were injected with monocrotaline (60 mg/kg intraperitoneal) or saline, followed with treatment with the selective ETA receptor antagonist LU135252 (LU; 50 mg.kg(-1).day(-1)) or with saline. After 3 weeks, haemodynamics, cardiac hypertrophy, ET-1 levels and cardiopulmonary ET-receptor-binding profile were evaluated. Monocrotaline (n =7) elicited marked pulmonary hypertension and right ventricular hypertrophy compared with controls (n =8). Both variables were substantially attenuated by LU therapy (n =8; P <0.05 for both). After monocrotaline, right ventricular ET-1 levels were more significantly increased than in the left ventricle (+198% compared with +127%; P <0.05). ETB receptor density was augmented (3-fold) in the right ventricle, whereas that of ETA receptors was not affected. LU treatment also significantly attenuated these alterations (P <0.05). In the lungs, ET-1 levels were not increased after monocrotaline, whereas the balance of ETB to ETA receptors was altered, with a trend toward a lower percentage of ETB than in the control rats. LU treatment did not affect these variables in the lungs. Therefore monocrotaline-induced pulmonary hypertension and right ventricular hypertrophy are associated with the up-regulation of ET-1 and ETB receptors in the right ventricle. These alterations are attenuated with the reduction of pulmonary hypertension and right ventricular hypertrophy after chronic blockade of the ETA receptors, supporting the role of the ET system in right ventricular hypertrophy.

Topics: Animals; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Endothelins; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Phenylpropionates; Pyrimidines; Radioligand Assay; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A

The present study evaluated the importance of ovarian functions and the renin-angiotensin system in the progression of the right ventricular (RV) hypertrophy. Female Sprague-Dawley rats were bilaterally ovariectomized (Ovx) and injected with monocrotaline (MCT, 60 mg/kg, sc). Four weeks after MCT-treatment, only the male and Ovx female rats showed marked RV hypertrophy. The hypertrophied RV of the male-MCT and Ovx-MCT rats exhibited remarkably elevated renin mRNA levels. Gene expression levels of angiotensinogen, TGF-beta1, and endothelin-1 in the hypertrophied RV also increased, but to the less degree than did the renin mRNA. To investigate beneficial effects of estrogen or enalapril on progression of the pulmonary hypertension and RV hypertrophy, histological changes of the lung and heart were examined. Sham-MCT female rats showed histological changes indicating pulmonary hypertension without RV hypertrophy. In contrast, Ovx-MCT rats showed marked RV hypertrophy with pathological changes, denoting severe pulmonary and myocardial injuries. Estrogen-or enalapril-treated Ovx-MCT rats did not show RV hypertrophy, and showed remarkably ameliorated ultrastructural changes in the lung and RV. These results from this rat model suggest that both estrogen and inhibition of the renin-angiotensin system have protective functions against the development of the pulmonary hypertension and cardiac remodeling.

Topics: Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Body Weight; Densitometry; Disease Progression; Enalapril; Endothelin-1; Estrogens; Female; Hypertrophy, Right Ventricular; Male; Microscopy, Electron; Monocrotaline; Ovariectomy; Rats; Rats, Sprague-Dawley; Renin; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger; Sex Factors; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ventricular Remodeling

Endothelin-1 (ET-1) mediates the development of pulmonary hypertension (PHT) in newborn rats exposed to 60% O(2) for 14 days, a model for human chronic neonatal lung injury. ET-1 production by d-14 rat pulmonary artery smooth muscle cells in vitro was markedly increased by thromboxane (TX) A(2) receptor agonists and inhibited by a competitive antagonist. We hypothesized that stimulation of the TX A(2) receptor contributed to O(2)-mediated PHT in vivo. Newborn rat pups received daily intraperitoneal injections of L670596, a competitive TX A(2) receptor antagonist, or 5,5-dimethyl-3-(3-fluorophenyl)4-(4-methylsulfonyl)phenyl-2(5H)-furanone (DFU), a cyclooxygenase-2 inhibitor, during 14 days of 60% O(2) or air exposure. L670596, but not DFU, prevented 60% O(2)-mediated right ventricular and small pulmonary vessel smooth muscle hypertrophy. Lung ET-1 content was significantly reduced by L670596 in 60% O(2)-exposed animals. We conclude that TX A(2) receptor activation, though not by TX A(2), caused upregulation of ET-1 and PHT in this model. A likely mediator is the stable lipid peroxidation product, 8-iso-prostane, which acts as an incidental ligand of the TX A(2) receptor and is a potent inducer of ET-1 production by cultured d-14 rat pulmonary artery smooth muscle cells in vitro.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Animals, Newborn; Blotting, Western; Carbazoles; Cells, Cultured; Cyclooxygenase Inhibitors; Dinoprost; Endothelin-1; F2-Isoprostanes; Furans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Immunohistochemistry; Lung; Muscle, Smooth, Vascular; Oxygen; Prostaglandin Antagonists; Prostaglandin-Endoperoxide Synthases; Pulmonary Artery; Rats; Receptors, Thromboxane; Thromboxane B2; Up-Regulation; Vasoconstrictor Agents

We studied the effect of long-term treatment with the oral endothelin (ET) ET(A) antagonist 2-benzo[1,3]dioxol-5-yl-3-benzyl-4-(4-methoxy-phenyl-)-4-oxobut-2-enoate-sodium (PD 155080; PD) on right ventricular intracellular calcium (Ca(2+)(i)) handling and cardiac and pulmonary artery function in control rats and rats with monocrotaline (MCT)-induced right-heart hypertrophy. Rats were given an intraperitoneal injection of either saline (controls; n = 9) or MCT (50 mg/kg; n = 12), resulting in pulmonary hypertension-induced myocardial hypertrophy, or MCT followed by the daily administration of PD (50 mg/kg) for 9 weeks (n = 9). After 9 weeks, right ventricular pressure was measured, and the hearts were removed and perfused in vitro. Right ventricular function and Ca(2+)(i) transients were recorded simultaneously on a beat-to-beat basis using aequorin. Surviving animals in the MCT group (58%) developed significant hypertrophy and had 2-fold higher right ventricular pressure and a prolonged duration of isovolumic contraction that correlated with a similar prolongation of the Ca(2+)(i) transient, indicating a reduced rate of Ca(2+) sequestration in hypertrophy (P < 0.05 versus control). In the PD group, all animals survived, and right ventricular pressure, diastolic relaxation, Ca(2+) transport kinetics, and peak systolic and end-diastolic wall stress were all normalized (P > 0.05 versus control); and pulmonary artery endothelial function was partly restored (P < 0.05 versus MCT and control groups). These results demonstrate for the first time that long-term ET(A) receptor antagonism normalizes myocardial cytosolic Ca(2+) modulation, which may contribute to the antihypertrophic and cardioprotective effect of ET(A) receptor therapy in this model.

Topics: Aequorin; Animals; Calcium; Calcium Signaling; Dioxoles; Endothelin Receptor Antagonists; Endothelin-1; Female; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; In Vitro Techniques; Luminescent Measurements; Monocrotaline; Myocardial Contraction; Perfusion; Poisons; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Ventricular Function, Right

Increased serine elastase activity has been implicated in the vascular remodeling associated with chronic hypoxia-related pulmonary hypertension in rats.. In this study we determined the time course of hypoxia-induced serine elastase activity in the murine lung and related this to initiation of a proteolytic cascade characterized by an increase in matrix metalloproteinases (MMPs). We then used transgenic mice in which overexpression of the selective serine elastase inhibitor elafin was targeted to the cardiovascular system to determine whether upregulation of a naturally occurring serine elastase inhibitor suppresses MMPs and the hemodynamic and structural response to chronic hypoxia (air at 380 mm Hg). In nontransgenic but not in elafin-transgenic mice, we documented a transient increase in serine elastase activity after 12 hours of hypoxic exposure attributed to a 30-kDa protein as determined by elastin zymography and fluorophosphonate/fluorophosphate-biotin labeling. Two days after hypoxia, the pro-forms of MMP-2 and MMP-9 were induced in the nontransgenic mice, but MMP-9 was suppressed in elafin-transgenic mice. Acute hypoxic vasoconstriction was similar in nontransgenic and elafin-transgenic littermates. Chronic hypoxia for 26 days resulted in >1-fold increase in right ventricular pressure (P<0.004) in nontransgenic compared with control or elafin-transgenic littermates. In the latter mice, normalization of the right ventricular pressure was associated with reduced muscularization and preservation of the number of distal vessels (P<0.04 for both comparisons).. Modulation of the severity of chronic hypoxia-induced pulmonary vascular disease could be a function of endogenously expressed serine elastase inhibitors.

Topics: Actins; Animals; Elastin; Endothelin-1; Hematocrit; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Kinetics; Matrix Metalloproteinases; Mice; Mice, Transgenic; Pressure; Proteinase Inhibitory Proteins, Secretory; Proteins; Pulmonary Artery; RNA, Messenger; Serine Proteinase Inhibitors; Up-Regulation; Ventricular Pressure

We examined whether overproduction of endogenous nitric oxide (NO) can prevent hypoxia-induced pulmonary hypertension and vascular remodeling by using endothelial NO-overexpressing (eNOS-Tg) mice. Male eNOS-Tg mice and their littermates (wild-type, WT) were maintained in normoxic or 10% hypoxic condition for 3 weeks. In normoxia, eNOS protein levels, Ca(2+)-dependent NOS activity, and cGMP levels in the lung of eNOS-Tg mice were higher than those of WT mice. Activity of eNOS and cGMP production in the lung did not change significantly by hypoxic exposure in either genotype. Chronic hypoxia did not induce iNOS expression nor increase its activity in either genotype. Plasma and lung endothelin-1 levels were increased by chronic hypoxia, but these levels were not significantly different between the 2 genotypes. In hemodynamic analysis, right ventricular systolic pressure (RVSP) in eNOS-Tg mice was similar to that in WT mice in normoxia. Chronic hypoxia increased RVSP and induced right ventricular hypertrophy in both genotypes; however, the degrees of these increases were significantly smaller in eNOS-Tg mice. Histological examination revealed that hypoxic mice showed medial wall thickening in pulmonary arteries. However, the increase of the wall thickening in small arteries (diameter <80 microm) by chronic hypoxia was inhibited in eNOS-Tg mice. Furthermore, muscularization of small arterioles was significantly attenuated in eNOS-Tg mice. Thus, we demonstrated directly that overproduction of eNOS-derived NO can inhibit not only the increase in RVSP associated with pulmonary hypertension but also remodeling of the pulmonary vasculature and right ventricular hypertrophy induced by chronic hypoxia.

Topics: Animals; Blood Pressure; Blood Vessels; Cyclic GMP; Endothelin-1; Female; Genotype; Heart Rate; Hematocrit; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Immunoblotting; Lung; Male; Mice; Mice, Transgenic; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Ventricular Function, Right; Ventricular Pressure

Endothelin (ET)-1 contributes to the regulation of pulmonary vascular tone by stimulation of the ET(A) and ET(B) receptors. Although activation of the ET(A) receptor causes vasoconstriction, stimulation of the ET(B) receptors can elicit either vasodilation or vasoconstriction. To examine the physiological role of the ET(B) receptor in the pulmonary circulation, we studied a genetic rat model of ET(B) receptor deficiency [transgenic(sl/sl)]. We hypothesized that deficiency of the ET(B) receptor would predispose the transgenic(sl/sl) rat lung circulation to enhanced pulmonary vasoconstriction. We found that the lungs of transgenic(sl/sl) rats are ET(B) deficient because they lack ET(B) mRNA in the pulmonary vasculature, have minimal ET(B) receptors as determined with an ET-1 radioligand binding assay, and lack ET-1-mediated pulmonary vasodilation. The transgenic(sl/sl) rats have higher basal pulmonary arterial pressure and vasopressor responses to brief hypoxia or ET-1 infusion. Plasma ET-1 levels are elevated and endothelial nitric oxide synthase protein content and nitric oxide production are diminished in the transgenic(sl/sl) rat lung. These findings suggest that the ET(B) receptor plays a major physiological role in modulating resting pulmonary vascular tone and reactivity to acute hypoxia. We speculate that impaired ET(B) receptor activity can contribute to the pathogenesis of pulmonary hypertension.

Topics: Animals; Animals, Genetically Modified; Blood Pressure; Dopamine beta-Hydroxylase; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; In Situ Hybridization; In Vitro Techniques; Lung; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Promoter Regions, Genetic; Pulmonary Artery; Pulmonary Circulation; Radioligand Assay; Rats; Rats, Inbred Strains; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Vascular Resistance; Vasoconstriction

It has been suggested that various vasoactive substances and growth factors are involved in left-ventricular myocardial hypertrophy and failure. However, limited data are available on the role of humoral factors involved in right-ventricular (RV) hypertrophy. To examine implications of humoral factors involved in the development of RV hypertrophy, altered mRNA expressions of the renin-angiotensin system (RAS), transforming growth factor (TGF)- beta1, endothelin-1 and nitric oxide synthase (NOS) were investigated in monocrotaline (MCT)-induced pulmonary hypertensive rats. Male Sprague-Dawley rats were treated with MCT (60 mg x kg(-1), s.c.) to induce a selective RV hypertrophy. Three or 6 weeks later, the heart was removed to determine the tissue gene expressions in the right and left ventricles (LV) by reverse transcription-polymerase chain reaction due to the relatively low mRNA expression levels of the RAS components in the ventricle (n= 6 in each group). MCT-treated rats showed a selective RV hypertrophy at weeks 3 and 6 of MCT treatment (the ratios of RV/body weight were 1.5- and 2.2-fold higher than the controls, respectively). Levels of renin and angiotensinogen mRNAs in the hypertrophied RV were significantly increased at both weeks 3 and 6 of MCT treatment. The angiotensin-converting enzyme mRNA level also increased approximately 2-fold at week 3. In contrast, RAS component mRNAs in the LV were not significantly altered by MCT treatment, except for a 1.8-fold increase of angiotensinogen mRNA at week 3. The expression of Ang II receptors, either AT1A or AT1B, was not significantly altered by MCT treatment. Furthermore, MCT treatment significantly increased TGF- beta1 mRNA levels in the RV at weeks 3 and 6, while it did not significantly affect them in the LV. Endothelin-1 mRNA expression was significantly higher in the RV at week 3, but was normalized at week 6 of MCT treatment. The gene expression of the endothelial constitutive isoform of NOS was increased in the RV at weeks 3 and 6, but not in the LV. Elevated gene expression of local RAS, along with TGF- beta1 and endothelin-1 in the present study may contribute to the development of RV hypertrophy. On the contrary, an enhanced ecNOS expression may be a mechanism counteracting the hypertrophy.

Topics: Animals; Disease Models, Animal; Endothelin-1; Gene Expression; Hypertrophy, Right Ventricular; Male; Monocrotaline; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Renin-Angiotensin System; Transforming Growth Factor beta; Transforming Growth Factor beta1

The effect of chronic hypoxia (CH) for 14 days on Ca2+ signaling and contraction induced by agonists in the rat main pulmonary artery (MPA) was investigated. In MPA myocytes obtained from control (normoxic) rats, endothelin (ET)-1, angiotensin II (ANG II), and ATP induced oscillations in intracellular Ca2+ concentration ([Ca2+]i) in 85-90% of cells, whereas they disappeared in myocytes from chronically hypoxic rats together with a decrease in the percentage of responding cells. However, both the amount of mobilized Ca2+ and the sources of Ca2+ implicated in the agonist-induced response were not changed. Analysis of the transient caffeine-induced [Ca2+]i response revealed that recovery of the resting [Ca2+]i value was delayed in myocytes from chronically hypoxic rats. The maximal contraction induced by ET-1 or ANG II in MPA rings from chronically hypoxic rats was decreased by 30% compared with control values. Moreover, the D-600- and thapsigargin-resistant component of contraction was decreased by 40% in chronically hypoxic rats. These data indicate that CH alters pulmonary arterial reactivity as a consequence of an effect on both Ca2+ signaling and Ca2+ sensitivity of the contractile apparatus. A Ca2+ reuptake mechanism appears as a CH-sensitive phenomenon that may account for the main effect of CH on Ca2+ signaling.

Topics: Adenosine Triphosphate; Angiotensin II; Animals; Caffeine; Calcium; Calcium Signaling; Chronic Disease; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Indoles; Intracellular Membranes; Male; Muscle, Smooth, Vascular; Pulmonary Artery; Rats; Rats, Wistar; Reference Values; Vasoconstriction; Vasodilator Agents; Vasomotor System

The purpose of this study was to test whether the Tester Moriyama rat (TMR), a strain that has a serotonin platelet storage-pool deficiency similar to that of the fawn-hooded rat (FHR), develops severe pulmonary hypertension (PH) upon exposure to mild hypoxia. We compared hemodynamic parameters in catheterized 10-week-old FHR, TMR, and control Wistar rats that had been raised from birth to 10 weeks of age under normoxia (PI(O(2)) approximately 150 mmHg) or mild hypobaric hypoxia (PI(O(2)) approximately 120 mmHg). Mean pulmonary artery pressure and right ventricle to left ventricle plus septum weight ratio were much higher in the mildly hypoxic FHR compared with the normoxic FHR. These parameters were only increased slightly by exposure to mild hypoxia in the TMR and Wistar rats. Mild hypoxia did not affect mean systemic artery pressure in any of the rat strains. Exposure of FHR to mild hypoxia from 4 to 10 weeks of age did not lead to development of PH. Endothelin-1 (ET-1) mRNA and peptide levels were increased in the hypertensive lungs of mildly hypoxic FHR compared with the normotensive lungs of normoxic FHR, and of normoxic and mildly hypoxic TMR and Wistar rats. These results suggest that mild hypoxia causes severe PH and upregulation of lung ET-1 expression in neonatal FHR but not in neonatal TMR, and that the period from birth to 4 weeks of age is critical for the development of the severe PH in the FHR. A serotonin PSPD does not predispose rats to hypoxia-induced PH.

Topics: Animals; Blood Pressure; Blotting, Northern; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Lung; Male; Platelet Storage Pool Deficiency; Radioimmunoassay; Rats; Rats, Mutant Strains; Rats, Wistar; RNA, Messenger; Serotonin; Species Specificity

Newborn rats exposed to 60% O(2) for 14 d demonstrated a bronchopulmonary dysplasia-like lung morphology and pulmonary hypertension. A 21-aminosteroid antioxidant, U74389G, attenuated both pulmonary hypertension and macrophage accumulation in the O(2)-exposed lungs. To determine whether macrophage accumulation played an essential role in the development of pulmonary hypertension in this model, pups were treated with gadolinium chloride (GdCl(3)) to reduce lung macrophage content. Treatment of 60% O(2)-exposed animals with GdCl(3) prevented right ventricular hypertrophy (p < 0.05) and smooth muscle hyperplasia around pulmonary vessels, but had no effect on morphologic changes in the lung parenchyma. In addition, GdCl(3) inhibited 60% O(2)-mediated increases in endothelin-1, 8-isoprostane, and nitrotyrosine residues. Organotypic cultures of fetal rat distal lung cells were subjected to cyclical mechanical strain to assess the potential role of GdCl(3)-induced blockade of stretch-mediated cation channels in these effects. Mechanical strain caused a moderate increase of endothelin-1 (p < 0.05), which was unaffected by GdCl(3), but had no effect on 8-isoprostane or nitric oxide synthesis. A critical role for endothelin-1 in O(2)-mediated pulmonary hypertension was confirmed using the combined endothelin receptor antagonist SB217242. We concluded that pulmonary macrophage accumulation, in response to 60% O(2), mediated pulmonary hypertension through up-regulation of endothelin-1.

Topics: Animals; Animals, Newborn; Bronchopulmonary Dysplasia; Cell Movement; Cells, Cultured; Dinoprost; Endothelin-1; F2-Isoprostanes; Gadolinium; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Infant, Newborn; Macrophages, Alveolar; Oxygen; Rats; Rats, Sprague-Dawley; Tyrosine

The cardiopulmonary profile of three rat strains (Sprague-Dawley, Wistar and High altitude-sensitive) was compared upon exposure to hypoxia (9% O2) for 0, 7 or 14 days. No differences were observed among the in vitro contractile (ET-1) and relaxant (carbachol) responses of pulmonary artery isolated from the three strains during normoxia. Chronic hypoxia decreased ET-1 contractile responses and diminished relaxant responses to carbachol similarly in all strains. In Sprague-Dawley, Wistar and High altitude-sensitive rats, pulmonary arterial pressure rose time-dependently and was elevated by 108%, 116% and 167%, respectively, after 14 days of hypoxia compared to normoxic controls. Right ventricular hypertrophy was increased by 51%, 93% and 55%, respectively, at 14 days. Hypoxia-induced hypertrophy and medial thickening in the pulmonary vasculature were more pronounced in High altitude-sensitive rats. Sprague-Dawley exhibited hypoxia-induced airway hyperresponsiveness to intravenous methacholine, but there were no hypoxia- or strain-related differences in in vitro tracheal contractility. Although each strain exhibited greater sensitivity for a particular hypoxia-induced parameter, pulmonary vascular functional and structural changes suggest that High altitude-sensitive rats represent a choice model of hypoxia-induced pulmonary hypertension.

Topics: Altitude; Animals; Carbachol; Disease Models, Animal; Endothelin-1; Endothelins; Hypertension, Pulmonary; Hypertrophy; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Male; Methacholine Chloride; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Rats, Wistar; Species Specificity; Trachea; Vasoconstriction; Vasodilation

We investigated the role of endothelin-1 (ET-1) in right ventricular function and intracellular Ca(2+)(Ca(2+)(i)) handling of isolated perfused rat hearts with right ventricular hypertrophy induced by monocrotaline (50 mg/kg). Nine weeks after monocrotaline (n=9) or saline (control n=9) treatment, hearts were perfused isovolumically at 37 degrees C and right ventricular function (fluid-filled balloon), right ventricular intracellular Ca(2+) transients (aequorin bioluminescence method) and the effects of ET-1 were determined. Monocrotaline-treated rats developed considerable right ventricular hypertrophy (right ventricular weight:body weight ratio: 1.07+/-0.13 v. 0.60+/-0.03 in controls P<0.05) and these hearts generated higher right ventricular systolic and diastolic pressure, but similar systolic and diastolic wall stress, indicating a compensated functional state. Hypertrophied hearts demonstrated a prolonged duration of isovolumic contraction (time to 90% decline from peak: 105+/-1 v 89+/-4 ms at 3 m M extracellular Ca(2+) P<0.05), but neither the time to peak pressure (71+/-3 ms) nor time to peak light (25+/-3 ms) were different from controls. The increased duration of contraction correlated with a similar prolongation of the Ca(2+)transient (time to 90% decline from peak: 72+/-4 v 50+/-3 ms P<0.05), indicating a reduced rate of Ca(2+)sequestration in hypertrophic right ventricles. Peak systolic intracellular Ca(2+)was similar in control and hypertrophied hearts (1.04+/-0.02 and 0.99+/-0.02 microM, P>0.05, n=6). ET-1 (1-300 p M) affected neither the time course of right ventricular contraction nor that of the Ca(2+)transient or peak systolic Ca(2+)concentrations. These data are the first measurements of right ventricular Ca(2+)transients in beating normal and hypertrophic hearts. We conclude that ET-1 plays no role in compensated hypertrophy because it affected neither right ventricular function nor intracellular Ca(2+)handling in this model.

Topics: Animals; Calcium; Calcium Signaling; Diastole; Endothelin-1; Hypertrophy, Right Ventricular; Ion Transport; Monocrotaline; Myocardial Contraction; Rats; Rats, Sprague-Dawley; Systole; Ventricular Function, Right

These studies document striking pulmonary vasoconstrictor response to nitric oxide synthase (NOS) inhibition in monocrotaline (MCT) pulmonary hypertension in rats. This constriction is caused by elevated endothelin (ET)-1 production acting on ETA receptors. Isolated, red blood cell plus buffer-perfused lungs from rats were studied 3 wk after MCT (60 mg/kg) or saline injection. MCT-injected rats developed pulmonary hypertension, right ventricular hypertrophy, and heightened pulmonary vasoconstriction to ANG II and the NOS inhibitor NG-monomethyl-L-arginine (L-NMMA). In MCT-injected lungs, the magnitude of the pulmonary pressor response to NOS inhibition correlated strongly with the extent of pulmonary hypertension. Pretreatment of isolated MCT-injected lungs with combined ETA (BQ-123) plus ETB (BQ-788) antagonists or ETA antagonist alone prevented the L-NMMA-induced constriction. Addition of ETA antagonist reversed established L-NMMA-induced constriction; ETB antagonist did not. ET-1 concentrations were elevated in MCT-injected lung perfusate compared with sham-injected lung perfusate, but ET-1 levels did not differ before and after NOS inhibition. NOS inhibition enhanced hypoxic pulmonary vasoconstriction in both sham- and MCT-injected lungs, but the enhancement was greater in MCT-injected lungs. Results suggest that in MCT pulmonary hypertension, elevated endogenous ET-1 production acting through ETA receptors causes pulmonary vasoconstriction that is normally masked by endogenous NO production.

Topics: Angiotensin II; Animals; Drug Combinations; Endothelin-1; Endothelins; Enzyme Inhibitors; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Lung; Male; Monocrotaline; Oligopeptides; omega-N-Methylarginine; Peptides, Cyclic; Piperidines; Rats; Rats, Sprague-Dawley; Vasoconstriction

The effects of SB 217242, a non-peptide endothelin (ET) receptor antagonist, were investigated against hypoxia-induced cardiopulmonary changes in high altitude-sensitive rats. In isolated pulmonary artery rings, SB 217242 (30 n m) antagonized ET-1-induced contractions with a p KB of 8.0. There was no difference in the sensitivity to ET-1 or the potency of SB 217242 in pulmonary artery from normoxic rats vs. rats exposed to hypoxia (9% O2) for 14 days. However, there was a marked reduction in the maximum response to ET-1, but not to KCl or phenylephrine, in pulmonary artery from hypoxic rats; this phenomenon was inhibited by treatment of animals with SB 217242 (10.8 mg/day, ip by osmotic pump) for the 14-day hypoxic period. Furthermore, there was a significant reduction in carbachol-induced, endothelium-dependent relaxation of precontracted pulmonary artery from hypoxic animals; SB 217242 treatment during the hypoxic period did not influence this difference. Vehicle-treated rats exposed to 14-day hypoxia had 173% higher pulmonary artery pressures and 75% higher right/left+septum ventricular mass ratios compared to normoxic animals. SB 217242 (3.6 or 10.8 mg/day, ip) markedly reduced (80 and 95%, respectively) hypoxia-induced increases in pulmonary artery pressure. Right ventricular hypertrophy was inhibited by 40% at the 10.8 mg/day dose. Marked medial thickening and luminal stenosis of small and medium-sized pulmonary arteries was observed in hypoxic rats. The SB 217242-treated, hypoxia-exposed rats had comparable small and medium-sized arteries to normoxic rats. Rats treated with SB 217242 (10.8 mg/day) for the last 14 days of a 28-day hypoxic exposure had significantly lower pulmonary artery pressures than those of vehicle-treated rats. In addition, the effects of the selective ETA receptor antagonist, SB 247083, and the selective ETB receptor antagonist, A-192621 (3.6 or 10.8 mg/day, ip), were compared against hypoxia-induced increases in pulmonary artery pressure and plasma ET concentrations. SB 247083, but not A-192621, inhibited hypoxia-induced pulmonary hypertension, whereas A-192621, but not SB 247083, significantly exacerbated hypoxia-induced increases in ET concentrations, suggesting that hypoxia-induced pulmonary pressor responses are mediated via ETA receptor activation, while ETB receptor blockade may alter clearance of hypoxia-induced elevated plasma ET. The inhibitory effects of SB 217242 on the functional and remodeling changes induced by

Topics: Altitude; Animals; Benzofurans; Carboxylic Acids; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Indans; Male; Propionates; Pulmonary Artery; Pyrrolidines; Random Allocation; Rats; Receptors, Endothelin

The effects of chronic hypoxia on the responses of rat large pulmonary arteries and veins to vasoactive agents have been examined. Endothelin-1-induced contractions of pulmonary arteries and pulmonary veins were reduced by chronic hypoxia. In contrast, chronic hypoxia augmented sarafotoxin 6c-induced contractile responses in pulmonary veins but not in pulmonary arteries. Chronic hypoxia augmented the constrictor effect of phenylephrine in pulmonary arteries, but not in pulmonary veins. The thromboxane receptor agonist, U46619 (9,11-dideoxy-9alpha,11alpha-epoxy-methanoprostaglandin++ + f2alpha) contracted pulmonary arteries and pulmonary veins, and although maximal responses were not altered in chronically hypoxic preparations, the EC50 value in pulmonary arteries was increased following chronic hypoxia. The relaxant effects of acetylcholine and isoprenaline on pulmonary arteries were potentiated by chronic hypoxia. In contrast, ionomycin-mediated relaxations of pulmonary arteries and pulmonary veins were reduced, while sodium nitroprusside-induced relaxation of pulmonary arteries and veins were not altered by chronic hypoxia. Previous studied have looked primarily at the effects of chronic hypoxia on pulmonary arteries. This data provides evidence that chronic hypoxia also causes selective changes in the reactivity of large pulmonary veins.

Topics: Animals; Endothelin-1; Hematocrit; Hypertrophy, Right Ventricular; Hypoxia; In Vitro Techniques; Male; Pulmonary Artery; Pulmonary Veins; Rats; Rats, Wistar; Time Factors; Vasoconstriction; Vasodilation

Experimental pulmonary hypertension induced in a hypobaric hypoxic environment (HHE) is characterized by structural remodeling of the heart and pulmonary arteries. Endothelin-1 (ET-1), a 21-amino acid peptide, is a novel and long-lasting vasoconstrictor that increases pulmonary arterial pressure in both in vivo and in vitro experiments. To study the effects of HHE on ET-1 activity in the lungs, 59 male rats were subjected to the equivalent of an altitude of 5500 m for 1 to 4 weeks. In rats exposed to HHE, the mean pulmonary arterial pressure increased significantly from 15.2+/-0.3 (ground level) to 30.6+/-1.5 mm Hg (5500-m level) at 4 weeks, whereas their mean systemic arterial pressure remained normal. The levels of ET-1 mRNA and protein, measured respectively by Northern blot analysis and enzyme immunoassay, increased rapidly in the lungs on exposure to HHE. By in situ hybridization and immunohistochemistry, respectively, ET-1 mRNA and protein were detected in control rats in nonciliated bronchiolar epithelial cells and alveolar epithelial cells, as well as in the endothelial cells of pulmonary arteries, but minimally in the smooth muscle cells of pulmonary arteries. ET-1 mRNA- and protein-reactive smooth muscle cells in pulmonary arteries and ET-1 mRNA-reactive airway epithelial cells were significantly more abundant in rats exposed to HHE than in ground level controls. These results suggest the possibility that in smooth muscle cells in pulmonary arteries and airway epithelial cells, ET-1 may play an autocrine or paracrine role in the remodeling of blood vessels during the development of the pulmonary hypertension that is induced by HHE.

Topics: Altitude; Animals; Blood Pressure; Endothelin-1; Endothelins; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Immunohistochemistry; In Situ Hybridization; Lung; Male; Osmolar Concentration; Protein Precursors; Pulmonary Artery; Rats; Rats, Wistar; Reference Values; RNA, Messenger; Tunica Media

Recent observations suggest the existence of a myocardial endothelin (ET) system and its possible involvement in left-ventricular myocardial hypertrophy and failure. However, nothing is known about the role of myocardial ET in right-ventricular hypertrophy.. Rats (80-100 g) were given an intraperitoneal injection of saline (controls) or monocrotaline (50 mg/kg) resulting in pulmonary hypertension-induced myocardial hypertrophy (n = 11 in both groups). After 10 weeks, the animals were sacrificed and hearts perfused in vitro to determine levels of big ET-1 and ET-1 in coronary effluent, interstitial fluid and ventricular tissue homogenates; plasma levels were also determined.. In monocrotaline-treated animals, weights of right ventricles were 1.5 and of right atria 1.8-fold higher than in controls (p < 0.05), indicating substantial right-ventricular hypertrophy as also evident from greatly increased myocardial production of atrial natriuretic peptide. Left-ventricular weights were not different. Release of big ET-1 in coronary effluent, and of ET-1 in coronary effluent and interstitial transudate were similar in control and hypertrophic hearts (p > 0.05). Disruption of endothelium with collagenase reduced release of both peptides close to zero, indicating endothelial (not myocardial) origin of the peptides. Levels of big ET-1 and ET-1 were similar in left ventricles of both experimental groups, but lower in right ventricles of hypertrophic than control hearts (p < 0.05), reflecting increased tissue mass rather than reduced peptide production. On the other hand, plasma levels of both peptides and of ANP were twofold and levels of angiotensin II 1.3-fold higher in rats with right-heart hypertrophy than in controls (p < 0.05 in each case).. These data do not support a role for local cardiac ET-1 and/or big ET-1 in right-ventricular hypertrophy, but point to blood-borne endothelins as possible mediators.

Topics: Analysis of Variance; Angiotensin II; Animals; Atrial Natriuretic Factor; Endothelin-1; Endothelins; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Monocrotaline; Myocardium; Perfusion; Poisons; Protein Precursors; Rats; Rats, Sprague-Dawley

Endothelin (ET)-1, a potent vasoconstrictor and smooth muscle mitogen, is produced from its precursor, preproET-1, by endothelin-converting enzyme (ECE)-1 activity. ET-1 may bind to two receptors, ETA and ETB, that mediate vasoconstriction and vasodilation in the ovine fetal lung, respectively. ET-1 contributes to high pulmonary vascular resistance in experimental perinatal pulmonary hypertension induced by ligation of the ductus arteriosus in the fetal lamb. Physiological studies in this model have demonstrated enhanced ETA- and diminished ETB-receptor activities and a threefold increase in lung immunoreactive ET-1 protein content. We hypothesized that increased ET production and an imbalance in receptor expression would favor vasoconstriction and smooth muscle cell hypertrophy in pulmonary hypertension and may be partially due to alterations in gene expression. To test this hypothesis, we studied lung mRNA expression of preproET-1, ECE-1, and the ETA and ETB receptors in normal and hypertensive fetal lambs. Total RNA was isolated from whole lung tissue in normal late-gestation fetuses (135 +/- 3 days; 147 days = term) and from animals with pulmonary hypertension after ductus arteriosus ligation for 8 days (134 +/- 4 days). Ductus arteriosus ligation increased right ventricular hypertrophy [control 0.56 +/- 0.02 vs. hypertension 0.85 +/- 0.05; right ventricle/(left ventricle + septum); P < 0.05]. Northern blot analysis was performed using cDNA probes and was normalized to the signal for 18S rRNA. We found a 71 +/- 24% increase in steady-state preproET-1 mRNA (P < 0.05) and a 62 +/- 5% decrease in ETB mRNA (P < 0.05) expression in ductus arteriosus ligation. ECE-1 and ETA-receptor mRNA expression did not change. We conclude that chronic intrauterine pulmonary hypertension after ductus arteriosus ligation increases steady-state preproET-1 mRNA and decreases ETB-receptor mRNA without changing ECE-1 mRNA or ETA-receptor mRNA expression. These findings suggest that increased ET-1 production and decreased ETB-receptor expression may contribute to increased vasoconstrictor tone in this experimental model of neonatal pulmonary hypertension.

Topics: Animals; Blotting, Northern; Endothelin-1; Endothelins; Fetal Diseases; Gene Expression; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Protein Precursors; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Sheep

Inhibition of endothelium-derived nitric oxide (NO) synthesis by L-arginine analogs such as nitro-L-arginine (L-NNA) elicits marked precapillary vasoconstriction in lungs from rats with chronic hypoxia-induced pulmonary hypertension. To investigate the role of endogenous endothelin (ET)-1 in L-NNA-induced vasoconstriction, we tested, in salt solution-perfused hypertensive lungs isolated from chronically hypoxic (3-4 wk at barometric pressure = 410 mmHg) adult male rats, if the pressor responses to L-NNA and exogenous ET-1 were inhibited by either separate or combined ETA and ETB receptor blockade. Whereas only combined pretreatment with 5 microM BQ-123 (selective ETA receptor blocker) and 5 microM BQ-788 (selective ETB receptor blocker) inhibited the response to 100 microM L-NNA, the response to 10 nM ET-1 was reduced by both BQ-123 alone and the combined blockers. Because exogenous ET-1 causes postcapillary vasoconstriction in salt solution-but not blood-perfused normotensive rat lungs, we next compared effects of ETA and ETB receptor blockade on L-NNA and ET-1 vasoconstrictions in blood-perfused hypertensive lungs. In this case, the combined but not the separate effects of BQ-123 and BQ-788 inhibited the responses to both L-NNA and ET-1. The last experiment showed that the use of BQ-788 to inhibit ETB receptor-mediated clearance of circulating ET-1 resulted in greater accumulation of endogenous ET-1 in the perfusate of hypertensive than of normotensive lungs. There was no difference between L-NNA-treated and vehicle control hypertensive lungs in accumulation of ET-1. These results suggest that increased endogenous levels of ET-1 acting through stimulation of both ETA and ETB receptors contribute to the vasoconstriction unmasked by inhibition of NO synthesis in hypertensive rat lungs. The increased ET-1 is apparently not due to the inhibition of NO synthesis, but, instead, its underlying stimulation of smooth muscle cell contraction is counteracted by NO activity.

Topics: Animals; Blood; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; In Vitro Techniques; Lung; Male; Nitroarginine; Perfusion; Pulmonary Circulation; Rats; Rats, Sprague-Dawley; Sodium Chloride; Vasoconstriction

Pulmonary hypertension is associated with endothelial dysfunction that may mediate or contribute to the disease process; among those abnormalities is an increase in circulating endothelin-1 levels. We investigated the effect of the orally active endothelin A receptor antagonist LU 135252 (LU) on the development of monocrotaline (MCT)-induced pulmonary hypertension and endothelial metabolic dysfunction. Rats were assigned to four groups by receiving a single dose of MCT or saline, followed by once-daily gavage with LU (50 mg/kg) or saline for 3 weeks. Plasma immunoreactive endothelin-1 levels doubled after MCT and were unaffected by LU therapy. The MCT-induced increase in right ventricular systolic pressure (72.5 +/- 15.9 mmHg) and hypertrophy (right ventricle/[left ventricle plus septum weight]; 0.58 +/- 0.08) were reduced by LU to 42.7 +/- 8.5 mmHg (P < .01) and 0.42 +/- 0.05 (P < .01), respectively. LU, however, did not modify MCT-induced pulmonary artery medial hypertrophy. Pulmonary vascular endothelial metabolic activity was evaluated in isolated lungs by measuring endothelium-bound angiotensin-converting enzyme activity using a synthetic angiotensin-converting enzyme substrate, 3H-benzoyl-phenylalanly-glycyl-proline. MCT reduced fractional 3H-benzoyl-phenylalanly-glycyl-proline hydrolysis (0.488 +/- 0.051, P < .01) which was normalized by LU therapy (0.563 +/- 0.050). LU treatment alone had no significant effect on any of these parameters. We conclude that the endothelin A antagonist LU reduces MCT-induced pulmonary hypertension and right ventricular hypertrophy and restores endothelial metabolic function. These results support the development of endothelin antagonists for the treatment of pulmonary hypertension and associated endothelial metabolic abnormalities.

Topics: Administration, Oral; Animals; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Male; Monocrotaline; Peptidyl-Dipeptidase A; Phenylpropionates; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Ventricular Function, Right

Endothelin-1 (ET-1), a potent vasoactive and mitogenic peptide, has been implicated in the pathogenesis of several forms of pulmonary hypertension. We hypothesized that nonspecific blockade of ET receptors would blunt the development of monocrotaline (MCT)-induced pulmonary hypertension in rats. A single dose of the nonspecific ET blocker bosentan (100 mg/kg) given to intact rats by gavage completely blocked the pulmonary vasoconstrictor actions of Big ET-1 and partially blunted hypoxic pulmonary vasoconstriction. After 3 wk, MCT-injected (105 mg/kg sc) rats gavaged once daily with bosentan (200 mg/kg) had lower right ventricular (RV) systolic pressure (RVSP), RV-to-body weight (RV/BW) and RV-to-left ventricular (LV) plus septal (S) weight [RV/(LV+S)] ratios and less percent medial thickness of small pulmonary arteries than control MCT-injected rats. Lower dose bosentan (100 mg/kg) had no effect on these parameters after MCT or saline injection. Bosentan raised plasma ET-1 levels but had no effect on lung ET-1 levels. Bosentan (200 mg/kg) also had no effect on wet-to-dry lung weight ratios 6 days after MCT injection. When given during the last 10 days, but not the first 11 days of a 3-wk period after MCT injection, bosentan reduced RV/(LV+S) compared with MCT-injected controls. We conclude that ET-1 contributes to the pathogenesis of MCT-induced pulmonary hypertension and acts mainly during the later inflammatory rather than the acute injury phase after injection.

Topics: Animals; Antihypertensive Agents; Bosentan; Cardiac Output; Endothelin Receptor Antagonists; Endothelin-1; Hemodynamics; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Male; Monocrotaline; Neovascularization, Pathologic; Organ Size; Poisons; Pulmonary Circulation; Rats; Rats, Sprague-Dawley; Sulfonamides

Endothelin-1 (ET-1) is known to have potent contractile and proliferative effects on vascular smooth muscle cells and is known to induce myocardial cell hypertrophy. We studied the pathophysiological role of endogenous ET-1 in rats with monocrotaline-induced pulmonary hypertension. Four-week-old rats were given a single subcutaneous injection of 60 mg/kg monocrotaline (MCT rats) or saline (control rats) and were killed after 6, 10, 14, 18, and 25 days. In the MCT rats, right ventricular systolic pressure progressively increased and right ventricular hypertrophy developed in a parallel fashion. The venous plasma ET-1 concentration also progressively increased, and this increase preceded the development of pulmonary hypertension. The isolated pulmonary artery exhibited a significantly weaker response to ET-1 in the MCT rats on day 25 but not on days 6 and 14. In the MCT rats, the expression of prepro ET-1 mRNA as measured by Northern blot analysis significantly increased in the heart on days 18 and 25, whereas it gradually decreased in the lungs. The peptide level of ET-1 in the lungs also significantly decreased in the pulmonary hypertensive stage. The expression of prepro ET-1 mRNA had increased by day 6 only in the kidneys. Continuous infusion of BQ-123, a selective ETA receptor antagonist, by an osmotic minipump (14.3 mg per day per rat for 18 days) significantly inhibited the progression of both pulmonary hypertension (right ventricular systolic pressure, 77.8 +/- 4.2 [mean +/- SEM] mm Hg [n = 10] versus 52.3 +/- 2.4 mm Hg [n = 7]; P < .01) and right ventricular hypertrophy (right ventricle/[left ventricle +/- septum], 0.56 +/- 0.03 [n = 10] versus 0.41 +/- 0.02 [n = 7]; P < .01). Histological examination revealed that BQ-123 also effectively prevented pulmonary arterial medial thickening. The inhibition of right ventricular hypertrophy by BQ-123 may be partly ascribed to the blockade of excessive stimulation of the heart by ET-1, in addition to the prevention of pulmonary hypertension. The present findings suggest that endogenous ET-1 contributes to the progression of cardiopulmonary alterations in rats with MCT-induced pulmonary hypertension.

Topics: Animals; Endothelin-1; Endothelins; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; In Vitro Techniques; Lung; Male; Monocrotaline; Peptides, Cyclic; Protein Precursors; Pulmonary Artery; Rats; Rats, Wistar; RNA, Messenger; Vasoconstriction