The Impact of Highly Selective Thoracic Sympathectomy on the Progression of Monocrotaline-induced Pulmonary Arterial Hypertension in Rats.

ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by persistently elevated pulmonary artery pressure and vascular resistance. Sympathetic overactivity in hypertension participates in pulmonary vascular remodeling and heart failure. The present study aims to explore the efficacy of highly selective thoracic sympathectomy (HSTS) on lowering pulmonary artery pressure, reversing pulmonary vascular remodeling, and improving right ventricular function in rats. A total of 24 Sprague-Dawley rats were randomly assigned into the control group ( n = 8) and experimental group ( n = 16). Rats in the control group were intraperitoneally injected with 0.9% normal saline, and those in the experimental group were similarly administered with received monocrotaline (MCT) injections at 60 mg/kg. Two weeks later, rats in the experimental group were further subdivided randomly into the MCT-HSTS group ( n = 8) and MCT-sham group ( n = 8), and they were surgically treated with HSTS and sham operation, respectively. Two weeks later, significantly lowered mean pulmonary artery pressure (mPAP), pulmonary artery systolic pressure (sPAP), and the ratio of sPAP to femoral artery systolic pressure (sFAP) were detected in the MCT-HSTS group than those of the MCT-sham group. In addition, rats in the MCT-HSTS group presented a significantly lower ratio of vascular wall area to the total vascular area (WT%), right ventricular hypertrophy index, and degrees of right ventricular fibrosis and lung fibrosis in comparison to those of the MCT-sham group. HSTS significantly downregulated protein levels of inflammasomes in pulmonary artery smooth muscle cells (PASMCs). Collectively, HSTS effectively reduces pulmonary artery pressure, pulmonary arteriolar media hypertrophy, and right ventricular hypertrophy in MCT-induced PAH rats. It also exerts an anti-inflammatory effect on PASMCs in PAH rats by suppressing inflammasomes and the subsequent release of inflammatory cytokines.

Sildenafil-induced priapism in a dog : an unusual case report.

BACKGROUND: Priapism is defined as erection that lasts for more than 4 h without sexual stimulation. There are various causes of priapism, but there are no reports of sildenafil-induced priapism in dogs. In human medicine, there were no pre-marketing reports of priapism caused by sildenafil, but post-marketing surveillance has shown that it is rare. In cases of pulmonary hypertension in dogs, sildenafil is the first-line drug of choice for symptomatic relief. CASE PRESENTATION: An 11-year-old neutered male Maltese dog that presented with tachypnea and cough was diagnosed with myxomatous mitral valve disease, American College of Veterinary Internal Medicine (ACVIM) stage C, and was treated medically. Eighteen months after the diagnosis, severe pulmonary hypertension occurred due to left heart disease. At 20 months postdiagnosis, pleural effusion occurred, and sildenafil (2 mg/kg twice daily) was added to the existing treatment. Two weeks later, the dyspnea recurred, confirming pleural fluid recurrence, and sildenafil was increased to 2 mg/kg thrice daily. One day later, the patient developed persistent erections and penile pain. Penile amputation and urethrostomy were recommended but were refused; therefore, analgesia and palliative care were provided. The patient died of acute dyspnea 22 months after the first presentation, with no specific priapism recurrence at the time of death. CONCLUSION: To the best of our knowledge, this is the first report of sildenafil-induced priapism in a dog with pulmonary hypertension.

MFN2-dependent mitochondrial dysfunction contributes to Relm-ß-induced pulmonary arterial hypertension via USP18/Twist1/miR-214 pathway.

Induction of resistin-like molecule ß (Relm-ß) and mitofusin 2 (MFN2) mediated aberrant mitochondrial fission have been found to be involved in the pathogenesis of pulmonary arterial hypertension (PAH). However, the molecular mechanisms underlying Relm-ß regulation of MFN2 therefore mitochondrial fission remain unclear. This study aims to address these issues. Primary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. The results showed that Relm-ß promoted cells proliferation in PASMCs, this was accompanied with the upregulation of USP18, Twist1 and miR-214, and downregulation of MFN2. We found that Relm-ß increased USP18 expression which in turn raised Twist1 by suppressing its proteasome degradation. Elevation of Twist1 increased miR-214 expression and then reduced MFN2 expression and mitochondrial fragmentation leading to PASMCs proliferation. In vivo study, we confirmed that Relm-ß was elevated in MCT-induced PAH rat model, and USP18/Twist1/miR-214/MFN2 axis was altered similar as in vitro. Targeting this cascade by Relm-ß receptor inhibitor Calhex231, proteasome inhibitor MG-132, Twist1 inhibitor Harmine or miR-214 antagomiR prevented the development of pulmonary vascular remodeling and therefore PAH in MCT-treated rats. In conclusion, we demonstrate that Relm-ß promotes PASMCs proliferation and vascular remodeling by activating USP18/Twist1/miR-214 dependent MFN2 reduction and mitochondrial fission, suggesting that this signaling pathway might be a promising target for management of PAH.

The Correlation between Lung Ultrasound and Pathology in Rat Model of Monocrotaline-Induced Pulmonary Hypertension.

Pulmonary hypertension (PH) is a progressive and complex pulmonary vascular disease with poor prognosis. The aim of this study was to provide a new understanding of the lung pathology of disease and a noninvasive method in monitoring the establishment of animal models for basic and clinical studies of PH, indeed to explore clinical application value of lung ultrasound for patients with PH. Totally 32 male SD rats were randomly divided into control group, MCT (monocrotaline) group, PDTC (pyrrolidine dithiocarbamate) group, and NS (normal saline) group. Rats in the MCT group, PDTC group, and NS group received single intraperitoneal injection of MCT, while the control group received the same dose of NS. Then, PDTC group and NS group received PDTC and NS daily for treatment at the end of the model. Each group received lung ultrasound examination and measurement of pulmonary arterial pressure (PAP). Then, the rats were sacrificed to take the lung specimens to being observed. The ultrasound and pathological results were analyzed with a semiquantitative score. With the pulmonary artery pressure increases, the MCT group had a higher pulmonary ultrasound score and pathological score compared with the control group (p < 0.05). After PDTC treatment, the pulmonary ultrasound score and the pathological score decline (p < 0.05). We investigated both lung ultrasound scores, and the pathological scores were positively correlated with mean pulmonary artery pressure (mPAP) (both r > 0.8, p < 0.0001). Moreover, lung ultrasound scores were positively correlated with pathological scores (r > 0.8, p < 0.0001). We elucidated lung ultrasound evaluation providing more evidence for the management of PH in the rat model. Moreover, lung ultrasound provided a noninvasive method in monitoring the establishment of animal models for basic and clinical studies of PH.

Indigo Leaves-Induced Pulmonary Arterial Remodeling without Right Ventricular Hypertrophy in Rats.

Indigo naturalis (IN), derived from the leaves of the indigo plant, is a traditional Chinese medicine that has historically been used for its anti-inflammatory properties in the treatment of various diseases, including ulcerative colitis (UC). However, long-term use of IN in UC patients is incontrovertibly associated with the onset of pulmonary arterial hypertension (PAH). To investigate the mechanisms by which IN induces PAH, we focused on the raw material of IN, indigo leaves (IL). Only the condition of long-term chronic (6 months) and high-dose (containing 5% IL in the control diet) administration of IL induced medial thickening in the pulmonary arteries without right ventricular hypertrophy in our rat model. IL administration for a month did not induce pulmonary arterial remodeling but increased endothelin-1 (ET-1) expression levels within endothelial cell (EC) layers in the lungs. Gene Expression Omnibus analysis showed that ET-1 is a key regulator of PAH and that the IL component indican and its metabolite IS induced ET-1 mRNA expression via reactive oxygen species-dependent mechanism. We identified the roles of indican and IS in ET-1 expression in ECs, which were linked to pulmonary arterial remodeling in an animal model.

Nephrectomy and high-salt diet inducing pulmonary hypertension and kidney damage by increasing Ang II concentration in rats.

BACKGROUND: Chronic kidney disease (CKD) is a significant risk factor for pulmonary hypertension (PH), a complication that adversely affects patient prognosis. However, the mechanisms underlying this association remain poorly understood. A major obstacle to progress in this field is the lack of a reliable animal model replicating CKD-PH. METHODS: This study aimed to establish a stable rat model of CKD-PH. We employed a combined approach, inducing CKD through a 5/6 nephrectomy and concurrently exposing the rats to a high-salt diet. The model's hemodynamics were evaluated dynamically, alongside a comprehensive assessment of pathological changes in multiple organs. Lung tissues and serum samples were collected from the CKD-PH rats to analyze the expression of angiotensin-converting enzyme 2 (ACE2), evaluate the activity of key vascular components within the renin-angiotensin-aldosterone system (RAAS), and characterize alterations in the serum metabolic profile. RESULTS: At 14 weeks post-surgery, the CKD-PH rats displayed significant changes in hemodynamic parameters indicative of pulmonary arterial hypertension. Additionally, right ventricular hypertrophy was observed. Notably, no evidence of pulmonary vascular remodeling was found. Further analysis revealed RAAS dysregulation and downregulated ACE2 expression within the pulmonary vascular endothelium of CKD-PH rats. Moreover, the serum metabolic profile of these animals differed markedly from the sham surgery group. CONCLUSIONS: Our findings suggest that the development of pulmonary arterial hypertension in CKD-PH rats is likely a consequence of a combined effect: RAAS dysregulation, decreased ACE2 expression in pulmonary vascular endothelial cells, and metabolic disturbances.

ß-catenin mediates monocrotaline-induced pulmonary hypertension via glycolysis in rats.

BACKGROUND: Metabolic abnormalities and immune inflammation are deeply involved in pulmonary vascular remodelling and the development of pulmonary hypertension (PH). However, the regulatory mechanisms of glycolysis in macrophages are still elusive. Cumulative evidence indicates that ß-catenin plays a crucial role in metabolic reprogramming. This study aimed to investigate the effect of ß-catenin on macrophage glycolysis in PH. METHODS: LPS-induced BMDMs were generated via in vitro experiments. A monocrotaline (MCT)-induced PH rat model was established, and the ß-catenin inhibitor XAV939 was administered in vivo. The role of ß-catenin in glycolysis was analysed. The degree of pulmonary vascular remodelling was measured. RESULTS: ß-catenin was significantly increased in both in vitro and in vivo models. In LPS-induced BMDMs, ß-catenin increased the levels of hexokinase 2 (HK2), phosphofructokinase (PFK), M2-pyruvate kinase (PKM2), lactate dehydrogenase (LDH), and lactate (LA) and the expression of inflammatory cytokines and promoted PASMC proliferation and migration in vitro. XAV939 decreased the level of glycolysis and downregulated the expression of inflammatory cytokines in vivo. MCT promoted pulmonary arterial structural remodelling and right ventricular hypertrophy, and XAV939 alleviated these changes. CONCLUSIONS: Our findings suggest that ß-catenin is involved in the development of PH by promoting glycolysis and the inflammatory response in macrophages. Inhibition of ß-catenin could improve the progression of PH.

A novel PDGFR inhibitor WQ-C-401 prevents pulmonary vascular remodeling in rats with monocrotaline-induced pulmonary arterial hypertension.

Platelet-derived growth factor (PDGF) is one of the most important cytokines associated with pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). PDGF receptor (PDGFR) inhibition exerted therapeutic effects on PAH in clinical trials, but serious side effects warrant the withdrawal of existing drugs. In this study, a novel highly selective PDGFR inhibitor WQ-C-401 was developed, and its effects on PDGFR signaling pathway and pulmonary vascular remodeling in PAH were investigated. Cell proliferation assays and Western blot analysis of PDGFRα/ß phosphorylation showed that WQ-C-401 inhibited PDGFR-mediated cell proliferation assay and suppressed PDGFR phosphorylation in a concentration-dependent manner. DiscoverX's KinomeScanTM technology confirmed the good kinome selectivity of WQ-C-401 (S score (1) of PDGFR = (0.01)). In monocrotaline (MCT)-induced PAH rats, intragastric administration of WQ-C-401 (25, 50, 100 mg/kg/d) or imatinib (50 mg/kg/d, positive control) significantly decreased right ventricular systolic pressure (RVSP). Histological analysis demonstrated that WQ-C-401 inhibited pulmonary vascular remodeling by reducing muscularization and fibrosis, as well as alleviated right ventricular hypertrophy in MCT-treated rats. In addition, WQ-C-401 suppressed MCT-induced cell hyperproliferation and CD68+ macrophage infiltration around the pulmonary artery. In vitro, WQ-C-401 inhibited PDGF-BB-induced proliferation and migration of human pulmonary arterial smooth muscle cells (PASMCs). Moreover, Western blot analysis showed that WQ-C-401 concertration-dependently inhibited PDGF-BB-induced phosphorylation of ERK1/2 and PDGFRß Y751, decreased collagen Ⅰ synthesis and increased alpha smooth muscle actin (α-SMA) expression in PASMCs. Collectively, our results suggest that WQ-C-401 is a selective and potent PDGFR inhibitor which could be a promising drug for the therapeutics of PAH by preventing pulmonary vascular remodeling.

Transcriptomic profiling highlights cell proliferation in the progression of experimental pulmonary hypertension in rats.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by pulmonary vascular remolding and occlusion, leading to the elevated pulmonary arterial pressures, right ventricular hypertrophy, and eventual heart failure if left untreated. Understanding the molecular mechanisms underlying the development and progression of pulmonary hypertension (PH) is crucial for devising efficient therapeutic approaches for the disease. Lung homogenates were collected weekly and underwent RNA-sequencing in the monocrotaline (MCT)-induced PH rat model to explore genes associated with PH progression. Statistical analyses revealed 1038, 1244, and 3125 significantly altered genes (P < 0.05, abs (log2fold change) > log21.5) between control and MCT-exposed rats during the first, second, and third week, respectively. Pathway enrichment analyses revealed involvement of cell cycle and innate immune system for the upregulated genes, GPCR and VEGF signaling for the downregulated genes. Furthermore, qRT-PCR validated upregulation of representative genes associated with cell cycle including Cdc25c (cell division cycle 25C), Cdc45, Top2a (topoisomerase IIα), Ccna2 (cyclin A2) and Ccnb1 (cyclin B1). Western blot and immunofluorescence analysis confirmed increases in PCNA, Ccna2, Top2a, along with other proliferation markers in the lung tissue of MCT-treated rats. In summary, RNA sequencing data highlights the significance of cell proliferation in progression of rodent PH.

Sodium Houttuyfonate Alleviates Monocrotaline-induced Pulmonary Hypertension by Regulating Orai1 and Orai2.

An increased intracellular Ca2+ concentration ([Ca2+]i) is a key trigger for pulmonary arterial smooth muscle cell (PASMC) proliferation and contributes greatly to pulmonary hypertension (PH). Extracellular Ca2+ influx via a store-operated Ca2+ channel, termed store-operated Ca2+ entry (SOCE), is a crucial mechanism for [Ca2+]i increase in PASMCs. Calcium release-activated calcium modulator (Orai) proteins, consisting of three members (Orai1-3), are the main components of the store-operated Ca2+ channel. Sodium houttuyfonate (SH) is a product of the addition reaction of sodium bisulfite and houttuynin and has antibacterial, antiinflammatory, and other properties. In this study, we assessed the contributions of Orai proteins to monocrotaline (MCT)-enhanced SOCE, [Ca2+]i, and cell proliferation in PASMCs and determined the effect of SH on MCT-PH and the underlying mechanism, focusing on Orai proteins, SOCE, and [Ca2+]i in PASMCs. Our results showed that: 1) Orai1 and Orai2 were selectively upregulated in the distal pulmonary arteries and the PASMCs of MCT-PH rats; 2) knockdown of Orai1 or Orai2 reduced SOCE, [Ca2+]i, and cell proliferation without affecting their expression in PASMCs in MCT-PH rats; 3) SH significantly normalized the characteristic parameters in a dose-dependent manner in the MCT-PH rat model; and 4) SH decreased MCT-enhanced SOCE, [Ca2+]i, and PASMC proliferation via Orai1 or Orai2. These results indicate that SH likely exerts its protective role in MCT-PH by inhibiting the Orai1,2-SOCE-[Ca2+]i signaling pathway.

Pneumonectomy combined with SU5416 or monocrotaline pyrrole does not cause severe pulmonary hypertension in mice.

In the field of pulmonary hypertension (PH), a well-established protocol to induce severe angioproliferation in rats (SuHx) involves combining the VEGF-R inhibitor Sugen 5416 (SU5416) with 3 wk of hypoxia (Hx). In addition, injecting monocrotaline (MCT) into rats can induce inflammation and shear stress in the pulmonary vasculature, leading to neointima-like remodeling. However, the SuHx protocol in mice is still controversial, with some studies suggesting it yields higher and reversible PH than Hx alone, possibly due to species-dependent hypoxic responses. To establish an alternative rodent model of PH, we hypothesized mice would be more sensitive to hemodynamic changes secondary to shear stress compared with Hx. We attempted to induce severe and irreversible PH in mice by combining SU5416 or monocrotaline pyrrole (MCTP) injection with pneumonectomy (PNx). However, our experiments showed SU5416 administered to mice at various time points after PNx did not result in severe PH. Similarly, mice injected with MCTP after PNx (MPNx) showed no difference in right ventricular systolic pressure or exacerbated pulmonary vascular remodeling compared with PNx alone. These findings collectively demonstrate that C57/B6 mice do not develop severe and persistent PH when PNx is combined with either SU5416 or MCTP.NEW & NOTEWORTHY We attempted to establish a mouse model of severe and irreversible pulmonary hypertension by substituting hypoxia with pulmonary overcirculation. To do so, we treated mice with either SU5416 or monocrotaline pyrrole after pneumonectomy and performed hemodynamic evaluations for PH. Despite this "two-hit" protocol, mice did not exhibit signs of severe pulmonary hypertension or exacerbated pulmonary vascular remodeling compared with PNx alone.

Pulmo-protection of long-term swimming exercise via improving insulin sensitivity in monocrotaline-induced pulmonary hypertensive rats.

Exercise has been recognized as an effective intervention in the treatment of pulmonary arterial hypertension (PAH), supported by numerous studies. However, the precise effects of exercise on pulmonary function remain to be fully elucidated. In this study, using a rat model of swimming exercise training and monocrotaline-induced PAH, we aimed to explore its impact on pulmonary morphology and function. Our investigations revealed that MCT-treated rats exhibited augmented mean pulmonary arterial pressure (MPAP) and pulmonary vascular remodeling, which can be attenuated by 4 weeks of swimming exercise training (60 min/day, 5 days/week). Notably, MCT-treated rats showed impaired pulmonary function, as manifested by decreased tidal volume and dynamic compliance, which were reversed by exercise training. Assessment of pulmonary substrate in PAH rats indicated a prominent pro-inflammatory substrate, evidenced by macrophage accumulation through quantitative immunohistological analysis of macrophage-like cell expression (CD68), and extracellular matrix remodeling, evaluated by Masson staining. Importantly, both the pro-inflammatory substrate and extracellular matrix remodeling were ameliorated by swimming exercise training. Additionally, serum biochemical analysis demonstrated elevated levels of low-density lipoprotein cholesterol and Apolipoprotein B following MCT treatment, which were reduced with exercise intervention. Moreover, exercise enhanced systemic insulin sensitivity in both MCT-treated and untreated rats. Notably, MCT and exercise treatment both decreased fasting blood glucose (FBG) levels in rats, whereas exercise training reinstated FBG levels to normal in MCT-treated rats. In summary, our study suggests that swimming exercise confers a pulmonary protective effect in MCT-induced PAH rats, highlighting the potential importance of exercise-based rehabilitation in the management of PAH.

Effects of nitric oxide inhalation on pulmonary arterial impedance: differences between normal and pulmonary hypertension male rats.

Nitric oxide (NO) inhalation improves pulmonary hemodynamics in participants with pulmonary arterial hypertension (PAH). Although it can reduce pulmonary vascular resistance (PVR) in PAH, its impact on the dynamic mechanics of pulmonary arteries and its potential difference between control and participants with PAH remain unclear. PA impedance provides a comprehensive description of PA mechanics. With an arterial model, PA impedance can be parameterized into peripheral pulmonary resistance (Rp), arterial compliance (Cp), characteristic impedance of the proximal arteries (Zc), and transmission time from the main PA to the reflection site. This study investigated the effects of inhaled NO on PA impedance and its associated parameters in control and monocrotaline-induced pulmonary arterial hypertension (MCT-PAH) male rats (6/group). Measurements were obtained at baseline and during NO inhalation at 40 and 80 ppm. In both groups, NO inhalation decreased PVR and increased the left atrial pressure. Notably, its impact on PA impedance was frequency dependent, as revealed by reduced PA impedance modulus in the low-frequency range below 10 Hz, with little effect on the high-frequency range. Furthermore, NO inhalation attenuated Rp, increased Cp, and prolonged transmission time without affecting Zc. It reduced Rp more pronouncedly in MCT-PAH rats, whereas it increased Cp and delayed transmission time more effectively in control rats. In conclusion, the therapeutic effects of inhaled NO on PA impedance were frequency dependent and may differ between the control and MCT-PAH groups, suggesting that the effect on the mechanics differs depending on the pathological state.NEW & NOTEWORTHY Nitric oxide inhalation decreased pulmonary arterial impedance in the low-frequency range (<10 Hz) with little impact on the high-frequency range. It reduced peripheral pulmonary resistance more pronouncedly in pulmonary hypertension rats, whereas it increased arterial compliance and transmission time in control rats. Its effect on the mechanics of the pulmonary arteries may differ depending on the pathological status.

GPS2 ameliorates cigarette smoking-induced pulmonary vascular remodeling by modulating the ras-Raf-ERK axis.

BACKGROUND: Mitogen-activated protein kinase (MAPK)signaling-mediated smoking-associated pulmonary vascular remodeling (PVR) plays an important role in the pathogenesis of group 3 pulmonary hypertension (PH). And G protein pathway suppressor 2 (GPS2) could suppress G-protein signaling such as Ras and MAPK, but its role in cigarette smoking -induced PVR (CS-PVR) is unclear. METHODS: An in vivo model of smoke-exposed rats was constructed to assess the role of GPS2 in smoking-induced PH and PVR. In vitro, the effects of GPS2 overexpression and silencing on the function of human pulmonary arterial smooth cells (HPASMCs) and the underlying mechanisms were explored. RESULTS: GPS2 expression was downregulated in rat pulmonary arteries (PAs) and HPASMCs after CS exposure. More importantly, CS-exposed rats with GPS2 overexpression had lower right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), and wall thickness (WT%) than those without. And enhanced proliferation and migration of HPASMCs induced by cigarette smoking extract (CSE) can be evidently inhibited by overexpressed GPS2. Besides, GPS2siRNA significantly enhanced the proliferation, and migration of HPASMCs as well as activated Ras and Raf/ERK signaling, while these effects were inhibited by zoledronic acid (ZOL). In addition, GPS2 promoter methylation level in rat PAs and HPASMCs was increased after CS exposure, and 5-aza-2-deoxycytidine (5-aza) inhibited CSE-induced GPS2 hypermethylation and downregulation in vitro. CONCLUSIONS: GPS2 overexpression could improve the CS-PVR, suggesting that GPS2 might serve as a novel therapeutic target for PH-COPD in the future.

Pulmonary hypertension impairs vasomotor function in rat diaphragm arterioles.

Pulmonary hypertension (PH) is a chronic, progressive condition in which respiratory muscle dysfunction is a primary contributor to exercise intolerance and dyspnea in patients. Contractile function, blood flow distribution, and the hyperemic response are altered in the diaphragm with PH, and we sought to determine whether this may be attributed, in part, to impaired vasoreactivity of the resistance vasculature. We hypothesized that there would be blunted endothelium-dependent vasodilation and impaired myogenic responsiveness in arterioles from the diaphragm of PH rats. Female Sprague-Dawley rats were randomized into healthy control (HC, n = 9) and monocrotaline-induced PH rats (MCT, n = 9). Endothelium-dependent and -independent vasodilation and myogenic responses were assessed in first-order arterioles (1As) from the medial costal diaphragm in vitro. There was a significant reduction in endothelium-dependent (via acetylcholine; HC, 78 ± 15% vs. MCT, 47 ± 17%; P < 0.05) and -independent (via sodium nitroprusside; HC, 89 ± 10% vs. MCT, 66 ± 10%; P < 0.05) vasodilation in 1As from MCT rats. MCT-induced PH also diminished myogenic constriction (P < 0.05) but did not alter passive pressure responses. The diaphragmatic weakness, impaired hyperemia, and blood flow redistribution associated with PH may be due, in part, to diaphragm vascular dysfunction and thus compromised oxygen delivery which occurs through both endothelium-dependent and -independent mechanisms.

Unilateral Lung Removal in Combination with Monocrotaline or SU5416 in Rodents: A Reliable Model to Mimic the Pathology of the Human Pulmonary Hypertension.

Pulmonary hypertension (PH) is a chronic and progressive disorder characterized by elevated mean pulmonary arterial pressure, pulmonary vascular remodeling, and the development of concentric laminar intimal fibrosis with plexiform lesions. While rodent models have been developed to study PH, they have certain deficiencies and do not entirely replicate the human disease due to the heterogeneity of PH pathology. Therefore, combined models are necessary to study PH. Recent studies have shown that altered pulmonary blood flow is a significant trigger in the development of vascular remodeling and neointimal lesions. One of the most promising rodent models for increased pulmonary flow is the combination of unilateral left pneumonectomy with a "second hit" of monocrotaline (MCT) or SU5416. The removal of one lung in this model forces blood to circulate only in the other lung and induces increased and turbulent pulmonary blood flow. This increased vascular flow leads to progressive remodeling and occlusion of small pulmonary arteries. The second hit by MCT or SU5416 leads to endothelial cell dysfunction, resulting in severe PH and the development of plexiform arteriopathy.

Effect of experimental pulmonary arterial hypertension on renal and bone parameters of rats submitted to resistance exercise training.

Pulmonary arterial hypertension (PAH) is characterized by right ventricular failure and diminished cardiac output, potentially leading to renal and bone impairments. In contrast, resistance exercise training (RT) offers cardiovascular and bone health benefits. This study aimed to assess the impacts of stable PAH induced by monocrotaline (MCT) and RT on renal morphometry, as well as bone morphometry and biomechanical properties in male Wistar rats. Four experimental groups, untrained control (UC, n=7), trained control (TC, n=7), untrained hypertensive (UH, n=7), trained hypertensive (TH, n=7), were defined. After the first MCT or saline injection (20 mg/kg), trained rats were submitted to a RT program (i.e., Ladder climbing), 5 times/week. Seven days later the rats received the second MCT or saline dose. After euthanasia, renal and femoral histomorphometry and femoral biomechanical properties were assessed. PAH reduced renal glomerular area and volume, which was prevented by the RT. While PAH did not harm the femoral morphometry, structural and mechanical properties, RT improved the femoral parameters (e.g., length, percentage of trabeculae and bone marrow, ultimte and yield loads). Experimental stable PAH promotes renal but not bone damages, whereas RT prevents renal deteriorations and improves the femoral morphological and biomechanical properties.

Corosolic acid attenuates platelet-derived growth factor signaling in macrophages and smooth muscle cells of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease that is characterized by vascular remodeling of the pulmonary artery. Pulmonary vascular remodeling is primarily caused by the excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), which are facilitated by perivascular inflammatory cells including macrophages. Corosolic acid (CRA) is a natural pentacyclic triterpenoid that exerts anti-inflammatory effects. In the present study, the effects of CRA on the viability of macrophages were examined using monocrotaline (MCT)-induced PAH rats and human monocyte-derived macrophages. Although we previously reported that CRA inhibited signal transducer and activator of transcription 3 (STAT3) signaling and ameliorated pulmonary vascular remodeling in PAH, the inhibitory mechanism remains unclear. Therefore, the underlying mechanisms were investigated using PASMCs from idiopathic PAH (IPAH) patients. In MCT-PAH rats, CRA inhibited the accumulation of macrophages around remodeled pulmonary arteries. CRA reduced the viability of human monocyte-derived macrophages. In IPAH-PASMCs, CRA attenuated cell proliferation and migration facilitated by platelet-derived growth factor (PDGF)-BB released from macrophages and PASMCs. CRA also downregulated the expression of PDGF receptor ß and its signaling pathways, STAT3 and nuclear factor-κB (NF-κB). In addition, CRA attenuated the phosphorylation of PDGF receptor ß and STAT3 following the PDGF-BB simulation. The expression and phosphorylation levels of PDGF receptor ß after the PDGF-BB stimulation were reduced by the small interfering RNA knockdown of NF-κB, but not STAT3, in IPAH-PASMCs. In conclusion, CRA attenuated the PDGF-PDGF receptor ß-STAT3 and PDGF-PDGF receptor ß-NF-κB signaling axis in macrophages and PASMCs, and thus, ameliorated pulmonary vascular remodeling in PAH.

Canagliflozin inhibits PASMCs proliferation via regulating SGLT1/AMPK signaling and attenuates artery remodeling in MCT-induced pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) was a devastating disease characterized by artery remodeling, ultimately resulting in right heart failure. The aim of this study was to investigate the effects of canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor (SGLT2i) with mild SGLT1 inhibitory effects, on rats with PAH, as well as its direct impact on pulmonary arterial smooth muscle cells (PASMCs). PAH rats were induced by injection of monocrotaline (MCT) (40 mg/kg), followed by four weeks of treatment with CANA (30 mg/kg/day) or saline alone. Pulmonary artery and right ventricular (RV) remodeling and dysfunction in PAH were alleviated with CANA, as assessed by echocardiography. Hemodynamic parameters and structural of pulmonary arteriole, including vascular wall thickness and wall area, were reduced by CANA. RV hypertrophy index, cardiomyocyte hypertrophy, and fibrosis were decreased with CANA treatment. PASMCs proliferation was inhibited by CANA under stimulation by platelet-derived growth factor (PDGF)-BB or hypoxia. Activation of AMP kinase (AMPK) was induced by CANA treatment in cultured PASMCs in a time- and concentration-dependent manner. These effects of CANA were attenuated when treatment with compound C, an AMPK inhibitor. Abundant expression of SGLT1 was observed in PASMCs and pulmonary arteries, while SGLT2 expression was undetectable. SGLT1 increased in response to PDGF-BB or hypoxia stimulation, while PASMCs proliferation was inhibited and beneficial effects of CANA were counteracted by knockdown of SGLT1. Our research demonstrated for the first time that CANA inhibited the proliferation of PASMCs by regulating SGLT1/AMPK signaling and thus exerted an anti-proliferative effect on MCT-induced PAH.