bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coordinated regulation of ENaC activity in the distal nephron by aldosterone and Ang II (1088.14)
Authors: Mamenko Mykola , Zaika Oleg , Prieto Minolfa , Jensen Behrana , Doris Peter , Navar Gabriel , Pochynyuk Oleh 
Published: June 2021

Recent studies point to direct actions of Ang II on ENaC‐mediated Na+ reabsorption in the distal nephron via stimulation of AT1R that occurs independently of aldosterone‐MR signaling. We used split‐opened distal nephrons from mice to probe the interaction between aldosterone and Ang II cascades in controlling ENaC activity during variations in dietary salt intake and in Ang II‐induced hypertension. Systemic MR inhibition abolished increases in the numbers of functionally active ENaC in response to low Na+ diet. Simultaneous inhibition of MR and AT1R at low dietary salt intake not only reduced the amount of active channels, but also decreased ENaC open probability and produced significantly greater natriuresis than either treatment alone. Chronic Ang II infusion stimulated ENaC activity greatly above levels observed during dietary sodium restriction. Importantly, maximal MR inhibition failed to suppress ENaC activity to control values. In contrast, blocking of de novo Ang II synthesis with captopril abolished stimulation of ENaC activity in Ang II infused animals. We conclude that during variations in dietary salt intake both aldosterone and Ang II contribute complementarily to the regulation of ENaC activity. In contrast, aldosterone‐independent stimulation of ENaC activity mediated by ACE dependent endogenous intratubular Ang II formation predominates in the setting of Ang II‐induced hypertension.Grant Funding Source: DK095029
Relationship between renal Ang (1‐7) induced sodium and water excretion and AT2 receptors (1088.7)
Authors: O’Neill Julie , Johns Edward 
Published: June 2021

Ang (1‐7) causes a natriuresis, which is mediated by intrarenal (IR) Mas receptors but is also dependent upon functional IR AT1 receptors. This study investigated the role played by IR AT2 receptors in mediating the renal excretory actions of Ang (1‐7) normally and when the RAS was stimulated by a low sodium diet. Male Wistar rats (n= 5‐6) were placed on normal (NNa+, 0.2%) or low (LNa+, 0.03%) sodium diets for 2 weeks. Rats were anaesthetized (chloralose/urethane) and prepared for mean arterial pressure (MAP) and left renal function measurement and IR infusion of saline and drugs. Data ±SEM were subjected to a Students t‐test. Basal MAP was 93±4 and 91±2mmHg and basal fractional sodium excretion (FENa) was 1.4±0.3 and 0.7±0.2 % in NNa+ and in LNa+ rats, respectively. IR infusion of Ang1‐7 had no effect on MAP but increased FENa by 227% and 427% in NNa+ and LNa+ rats respectively (both P<0.05). In the presence of PD123319, Ang (1‐7) induced increases in FENa excretion were blunted at 75% and 34% in NNa+ and LNa+ rats respectively (both P<0.05). These data imply that functional IR AT2 receptors may have a permissive effect upon the natriuretic actions of Ang (1‐7) at a tubular level.Grant Funding Source: IRCSET
Newly identified caveolin‐1 mutation associated with heritable human pulmonary arterial hypertension mediates hyperproliferation via augmented calcium signaling (1089.10)
Authors: Marsboom Glenn , Theriault Kraig , Debroy Auditi , Mao Mao , Baig Saqib , Tiruppathi Chinnaswamy , Bonini Marcelo , Rehman Jalees , Austin Eric , Malik Asrar 
Published: June 2021

Objective: Recently, a new mutation in Caveolin‐1 (Cav‐1) was identified in a family with heritable pulmonary arterial hypertension (hPAH), but the underlying molecular mechanisms by which the Cav‐1 mutation leads to hPAH are poorly understood.Methods: Human dermal fibroblasts were obtained from 3 healthy control subjects and 3 hPAH patients with the Caveolin‐1 mutation.Results: Patient fibroblasts had a markedly higher proliferative rate than those of control subjects (34±5 vs. 19±4%, P<0.05). Since calcium is an important regulator of cell proliferation, we compared maximal cytoplasmic calcium influx in response to the SERCA inhibitor thapsigargin. We found that calcium influx was higher in fibroblasts with a Cav‐1 mutation (2.38‐fold increase, P<0.005). Also, fibroblasts with a Cav‐1 mutation exhibited higher oxidative stress (2.5‐fold increase in H2O2 P<0.01, 4‐fold increase in peroxynitrite P<0.001).Conclusions: The newly identified Caveolin‐1 in hPAH patients as associated higher fibroblast proliferation, aberrant calcium signaling, and high levels of oxidative stress. These signaling pathways may be promising targets for novel therapies in hPAH and validate the role of Cav‐1 in clinical PAH. Since Cav‐1 is a disease modifier in experimental PAH, our findings may also prove valuable for understanding the pathophysiology of non‐heritable PAH.
Rosiglitazone attenuated endothelin‐1‐induced vasoconstriction of pulmonary arteries in the rat model of pulmonary arterial hypertension (1089.13)
Authors: Liu Yahan , Tian XiaoYu , Huang Yu , Wang Nanping 
Published: June 2021

Pulmonary arterial hypertension (PAH) can lead to right ventricular failure and death. Endothelin (ET)‐1 activation has been demonstrated in plasma and lung tissue of PAH patients and animal models. Peroxisome proliferator‐activated receptor γ (PPARγ) agonists have been shown to ameliorate PAH. To investigate the mechanism for anti‐vasoconstrictive effects of rosiglitazone in PAH, Sprague‐Dawley rats were exposed to chronic hypoxia (10% oxygen) for 3 weeks. ET‐1 caused enhanced constriction of pulmonary arteries from such PAH rats. Oral gavage with PPARγ agonist rosiglitazone (20 mg/kg per day) for 3 days in vivo reversed the vasocontractive effect of ET‐1. This effect was abolished by L‐NAME, indicating a NO‐dependent mechanism. The attenuated ET‐1‐induced contraction of rosiglitazone was restored by an ETBR antagonist A192621, whereas this antagonist did not modulate the evoked pulmonary arterial contractions from normoxia and PAH rats. Rosiglitazone increased protein level of ETBR in pulmonary arteries from PAH rats. These results demonstrated that rosiglitazone attenuated ET‐1‐induced vasoconstriction in PAH through the upregulation of endothelial ETBR and suggested the therapeutic use of PPARγ agonists in PAH.Grant Funding Source: Supported by Grants from the National Science Foundation of China (81220108005, 81300189)
Actin polymerization contributes to enhanced pulmonary arterial vasoconstrictor reactivity following chronic hypoxia (1089.15)
Authors: Sheak Joshua , Sands Michelle , Snow Jessica , Gonzalez Bosc Laura , Jernigan Nikki , Walker Benjimen , Resta Thomas 
Published: June 2021

Chronic hypoxia (CH) induces basal pulmonary arterial tone and augments vasoconstrictor reactivity to endothelin‐1 (ET‐1) through Rho kinase‐dependent Ca2+ sensitization. Considering that dynamic actin cytoskeletal reorganization is integral to tension generation in smooth muscle, and that Rho kinase is important in mediating actin polymerization, we hypothesized that actin polymerization is required for both basal pulmonary arterial tone and enhanced ET‐1‐dependent vasoconstriction following CH. To test this hypothesis, we assessed effects of the actin polymerization inhibitors, cytochalasin B (10‐5 M) and latrunculin A (10‐5 M), on the development of tone in response to increasing intraluminal pressure steps (5‐45 mmHg) in isolated, endothelium‐disrupted pulmonary arteries (~150 μm diameter) from control and CH (4 wk at 0.5 atm) rats. Further experiments examined effects of cytochalasin B on constrictor responses to ET‐1 (10‐10 ‐ 10‐7 M) under Ca2+‐clamp conditions in arteries from each group. Consistent with our hypothesis, inhibitors of actin polymerization prevented basal tone (p<0.05 vs. vehicle) and attenuated ET‐1‐mediated constriction (p<0.05 vs. vehicle) in arteries from CH rats, while having no effect on control arteries. We conclude that actin polymerization is necessary for generation of basal pulmonary arterial tone and enhanced vasoconstrictor reactivity to ET‐1 following CH.Grant Funding Source: Supported by NIH R01 HL88192 and NIH T32 HL07736
The role of mitochondrial reactive oxygen species in hypoxia‐induced pulmonary hypertension (1089.16)
Authors: Adesina Sherry , Hart C. , Sutliff Roy 
Published: June 2021

Oxidative stress plays a critical role in pulmonary hypertension (PH) pathogenesis. The specific reactive oxygen species (ROS) responsible have not been defined, though mitochondrial ROS likely contribute. We hypothesize that mitochondrial O2•− and H2O2 promote PH pathogenesis.Hypoxia effects on mitochondrial O2•− and H2O2 were measured using mitoPY1 and mitoSOX in human pulmonary arterial endothelial cells (HPAECs) exposed to normoxia (21% O2) or hypoxia (1% O2) for 72 hours. Mouse models with mitochondria‐targeted SOD2 (TghSOD2) or catalase (mCAT) expression were used to modulate mitochondrial ROS. Control and transgenic mice were exposed to normoxia (21% O2) or hypoxia (10% O2) for 3 weeks. ROS levels (confocal microscopy and Amplex red assay), Nox mRNA levels (qRT‐PCR), and proliferation and remodeling (α‐smooth muscle actin, α‐SMA, staining) were measured at the conclusion of the study.Hypoxia exposed HPAECs had increased mitochondria‐derived O2•− and H2O2 (p 蠄 0.5). Compared to control, mCAT expression prevented hypoxia‐induced increases in lung H2O2, Nox2, Nox4, and PCNA mRNA, and α‐SMA staining (p 蠄 0.5). Hypoxia‐induced alterations in these markers were exacerbated in TghSOD2 lungs (p 蠄 0.5). These studies suggest that targeted attenuation of mitochondria‐derived H2O2 attenuates pulmonary vascular derangements involved in PH pathogenesis.Grant Funding Source: VA Merit Review 1I01BX001910. NIH grants DK074519/ HL102167 (CMH/RLS). NRSA 1F31HL114386 ‐ 01A1 SEA
Implication of miR‐204/RUNX2‐dependent calcification pathway in pulmonary arterial hypertension (1089.23)
Authors: Pflieger Aude , Meloche Jolyane , Tremblay Eve , Breuils‐Bonnet Sandra , Provencher Steeve , Bonnet Sebastien 
Published: June 2021

Introduction: Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by occurrence of several vascular lesions. Interestingly, some biological pathways implicated in these lesions are also implicated in calcification processes. Nonetheless, the role for calcification lesions in PAH has never been explored. miR‐204, which is downregulated in PAH, is implicated in calcification processes by directly regulating the pro‐calcification transcription factor RUNX2. RUNX2 also regulates cell proliferation by activating HIF‐1. Thus, we hypothesized that miR‐204 downregulation in PAH triggers RUNX2 expression promoting calcification and vascular lesions in PAH. Methods and results: Using human explanted lungs, fresh distal pulmonary arteries (PAs) and freshly isolated pulmonary artery smooth muscle cells (PASMC) from both control and PAH patients, we demonstrated a significant downregulation of miR‐204 and an upregulation of RUNX2 in PAH compared to controls. The increase in RUNX2 in PAH patients was associated with an increase in distal PA calcification. Gain‐ and loss‐of‐function approaches in human PASMC showed that downregulation of miR‐204 in control PASMC increases RUNX2 expression, while increased miR‐204 in PAH‐PASMC decrease it. More importantly, restoring miR‐204 or decreasing RUNX2 expression in PAH‐PASMC decreases proliferation, resistance to apoptosis and alkaline phosphatase activity. Finally, in Sugen/hypoxia PAH rat model, nebulization of either miR‐204 mimic or RUNX2 siRNA significantly improves PAH.Conclusion: Taken together, our study uncovers a new miR‐204/RUNX2 axis contributing to both calcified lesions and vascular remodeling in distal PA of PAH patients. More experiments are required to further explore the role of RUNX2 in PAH pulmonary artery calcification. This study might lead to the discovery of new potential therapeutic strategies for patients suffering of PAH.
Augmented pulmonary artery pressure response during exercise in adults born extremely preterm, but not in those with bronchopulmonary dysplasia (1089.4)
Authors: Laurie Steven , Elliott Jonathan , Beasley Kara , Mangum Tyler , Goodman Randall , Gladstone Igor , Lovering Andrew 
Published: June 2021

Advances in perinatal care in the post surfactant era have increased survivability of infants born extremely preterm (<32 weeks gestation), yet long‐term cardiopulmonary consequences of prematurity in adulthood remain largely unexplored. We studied adults who developed new bronchopulmonary dysplasia (BPD, 22.7 yrs), preterm subjects who did not develop BPD (PRE, 21.1 yrs), and fullterm controls (CONT, 22.7 yrs) at rest and during cycle ergometer exercise in the forward leaning aerobar position. Subjects exercised for 3 min at 25%, 50% and 75% of their maximum workload attained at VO2max from a separate visit. We measured metabolic rate, and pulmonary artery systolic pressure (PASP) with ultrasonography, at rest and during exercise. There were no differences in PASP between the groups at rest. At 50% and 75% VO2max, PASP was higher in PRE subjects than in BPD and CONT subjects, which were not significantly different from each other at any exercise intensity. The slope of the PASP to VO2 relationship was significantly greater in PRE subjects compared to BPD and CONT. These data suggest PRE subjects have a reduced ability for the pulmonary vasculature to accommodate increases in cardiac output during exercise compared to CONT and BPD subjects. Further research is needed to determine if this augmented pressure response during exercise may predispose PRE subjects to developing pulmonary arterial hypertension.Grant Funding Source: Supported by: AHA Scientist Development Grant
TRPV4‐associated alterations of Ca2+ pulsars in a murine model of pulmonary hypertension secondary to heart failure (1090.11)
Authors: Dayeh Nour , Safar Steven , Gillis Marc‐Antoine , Blanchette Alexandre , Dupuis Jocelyn , Ledoux Jonathan 
Published: June 2021

Heart failure is the most frequent cause of pulmonary hypertension (PH) (group 2). Pathophysiological mechanisms modulating pulmonary vascular tone and leading to group 2‐PH are poorly defined. Since Ca2+ homeostasis is crucial to endothelial control of vascular tone, mechanisms involved, including TRPV4 channels, may be altered. This study aimed to characterize intracellular Ca2+ dynamics in pulmonary endothelium and their alterations in group 2 PH. A mouse model of group 2 PH was developed and 3rd order resistance arteries were isolated to investigate endothelial intracellular Ca2+. TRPV4 involvement was studied using a high‐speed confocal microscope. Characterization of endothelial localized calcium transients, similar to Ca2+ pulsars, was carried out in pulmonary arteries from control mice. Exposure of Sham arteries to GSK1016790A (100 nM), a TRPV4‐agonist, increased the frequency (1.5 fold) of Ca2+ pulsars. However, exposure to GSK1016790A had little if any effect on Ca2+ dynamics in PH arteries. TRPV4 channel expression at both mRNA and protein levels within pulmonary endothelium was confirmed by qPCR, IHC and WB approaches. Our data suggest a potential role for endothelial TRPV4 in vasoregulatory alterations involving local Ca2+ dynamics. This study strengthens our understanding of endothelial Ca2+ dyshomeostasis occurring in a clinically relevant model of PH.Grant Funding Source: FRQS, HSFC, FICM, CIHR
Shear stress enhance intracellular Ca2+ in PASMC from patients with idiopathic pulmonary arterial hypertension (1090.13)
Authors: Song shanshan , Tang Haiyang , Smith Kimberly , Makino Ayako , Yuan Jason 
Published: June 2021

Idiopathic pulmonary arterial hypertension (IPAH) is a fatal and progressive disease which is attributed to elevated pulmonary arterial pressure and pulmonary vascular resistance due in part to sustained pulmonary vasoconstriction and vascular remodeling. Pulmonary arterial smooth muscle cells (PASMC) are normally shielded from exposure to shear stress and sense small flow shear through transmural interstitial flow driven by transvascular pressure differential. However, in the context of endothelial injury or enhanced vascular permeability caused by increased pulmonary arterial pressure, PASMC are exposed to shear stress or to enhanced transmural interstitial flow. Shear stress can increase cytosolic Ca2+ concentration ([Ca2+]cyt). An increase in [Ca2+]cyt in PASMC is a major trigger for vasoconstriction and a key stimulus for cell proliferation, which contribute to vascular remodeling. We show here that shear stress induced increased [Ca2+]cyt in PASMC from patients with IPAH compared with control. Fluid flow shear stress induced enhanced transient and plateau [Ca2+]cyt and larger Ca2+ oscillation amplitude in IPAH PASMC than in control. Expression of TRPM7 and TRPV4 channels, two Ca2+ channels implicated in response to shear stress, both were increased in IPAH PASMC. TRPM7 and TRPV4 blockers 2‐APB and Ruthenium red inhibited flow shear‐induced enhanced [Ca2+]cyt in IPAH PASMC respectively, and the TRPM7 agonist bradykinin induced higher [Ca2+]cyt and [Mg2+]cyto increase in IPAH PASMC than in control, so did TRPV4 agonist 4α□PDD. Knocking down TRPM7 and TRPV4 by siRNA decreased [Ca2+]cyt increase induced by fluid flow. These results demonstrate that fluid flow shear stress induce enhancement of [Ca2+]cyt in IPAH PASMC through the Ca2+ channels TRPM7 and TRPV4, and that mechanical sensitive channels TRPM7 and TRPV4 play a critical role in PAH by modulating [Ca2+]cyt homeostasis.Grant Funding Source: Supported by NIH R01(HL 066012, HL 115014))
CD4+ T cells contribute to chronic hypoxia‐induced pulmonary hypertension (1090.5)
Authors: Maston Levi , Cannon Judy , Resta Thomas , González Bosc Laura 
Published: June 2021

We have previously demonstrated that adaptive immune cells contribute to chronic hypoxia (CH)‐induced pulmonary hypertension (PH). Within the adaptive immune system, CD4+ T cells are required for initiating and maintaining inflammation, suggesting these cells could play an important role in the pathology of hypoxic PH. Therefore, we hypothesized that CD4+ T cells contribute to CH‐induced PH. To test this hypothesis, we isolated CD4+ T cells from lymph nodes of male C57BL/6 wild‐type (WT) mice by negative selection or B cells from spleens of T cell receptor knockout (KO) mice lacking T cells. We then adoptively transferred B cells and CD4+ T cells separately into RAG1 KO mice, which lack mature T and B cells. WT mice and adoptively transferred and sham‐treated RAG1 KO mice were exposed to normoxia or CH (PB=380 mmHg) for 3 weeks, at which point peak right ventricular systolic pressure (RVSP) was measured. As previously observed, sham‐treated RAG1 KO mice were protected from the development of CH‐induced PH as indicated by significantly lower RVSP compared to CH WT mice (p<0.05). In support of our hypothesis, adoptive transfer of CD4+ T cells, but not B cells, to CH RAG1 KO mice restored the PH phenotype to the level of CH WT mice. We conclude that CD4+ T cells are sufficient to drive CH‐induced PH.Grant Funding Source: Supported by T32 HL07736, R01HL088151, R01 HL088192, R01 AI097202
Selective knockout of acid α‐glucosidase GAA gene expression in the medulla alters breathing (1091.3)
Authors: Fuller David , Elmallah Mai Kamal , Ross Heather , Cerreta Anthony , Corti Manuela , Smith Barb , Poirier Amy , Mandel Ronald , Byrne Barry 
Published: June 2021

Pompe disease results from gene mutations in GAA ‐ an enzyme necessary to degrade lysosomal glycogen. Hypoventilation is a hallmark feature historically attributed to Pompe‐associated muscle pathology but the contribution of brain to this deficit is unclear. In ongoing experiments, we are using a Cre‐Lox recombination approach to knockout (KO) the GAA gene in medullary respiratory neurons while leaving somatic muscle expression unaltered. AAV vectors driving Cre recombinase were injected into the ventrolateral medulla of C57Bl/6 mice in which exons 4‐8 of the GAA gene were floxed with loxP sites. Whole body plethysmography was used to assess breathing patterns at 1‐2 months post‐injection during baseline (21% O2) and respiratory challenge (7% CO2, 21% O2). During baseline conditions at 2 months, AAV‐Cre injected mice had increased ventilation compared to saline injected mice (P<0.05). However, during respiratory challenge at 2 months, the AAV‐Cre group had a reduced ventilatory response (P<0.05). These preliminary results demonstrate that medullary GAA KO can alter breathing. Our working hypothesis is that neuronal glycogen accumulation leads to dysfunction in medullary networks, and the increased baseline breathing indicates a compensatory response to ongoing neuropathology. The blunted hypercapnic ventilatory response may reflect an inability to fully compensate for the ongoing neuropathology.Grant Funding Source: Funding: Parker B. Francis Fellowship (MKE), 1R21NS081431‐01 (DDF, BJB)
vGluT2 is necessary for rostroventrolateral medullary catecholaminergic neurons to drive respiration and parasympathetic activity (1091.4)
Authors: Holloway Ben , Abbott Steve , Viar Ken , Guyenet Patrice 
Published: June 2021

Catecholaminergic neurons located in the rostroventrolateral medulla (CA‐RVLM) contribute to sympathetic, parasympathetic, and neuroendocrine responses and are activated by hypotension, hypoglycemia, hypoxia, infection, pain, and psychological stress. Most CA‐RVLM express vGluT2, and work on slices suggests they release glutamate but the significance of vGluT2 in these neurons in vivo is unestablished. To investigate the role of vGluT2 in CA‐RVLM in vivo, we crossed floxed vGluT2 mice with dopamine‐β‐hydroxylase (DβH) Cre mice, creating mice with vGluT2 selectively deleted from DβH neurons (cKO mice). We then injected a Cre‐dependent AAV2 that expresses channelrhodopsin fused to mCherry into the RVLM of cKO or control mice. In both experimental and control groups, photostimulation activated the channelrhodopsin+ CA‐RVLM. Photostimulation of CA‐RVLM in control mice increased respiratory rate in conscious mice and efferent vagal nerve activity in anesthetized mice, while in cKO mice, photostimulation had no affect on respiratory rate or efferent vagal nerve activity. Thus, vGluT2 is necessary for CA‐RVLM neurons to activate respiration and increase vagal nerve activity.Grant Funding Source: Supported by NIH HL28785 and HL74011 to PGG, and American Heart Association 11post7170001 to SBGA
Optogenetic stimulation of adrenergic C1 neurons in rat produces arousal from sleep, sighs and increases breathing frequency (1091.5)
Authors: Burke Peter , Abbott Steven , Hodges Walter , Viar Kenneth , Coates Melissa , Stornetta Ruth , Guyenet Patrice 
Published: June 2021

Acute hypoxia causes hyperventilation, sighs and arousal from sleep. The role of C1 neurons in mediating hypoxia counter‐regulation in a behaving animal remains untested. We determined sufficiency by optogenetic methods. Channelrhodopsin‐2 was selectively introduced into C1 neurons of Tyrosine Hydroxylase Cre‐driver rats (Cre/0) with a Cre‐dependant adeno‐associated viral vector (AAV2 DIO‐EF1alpha‐ChR2‐EYFP). Sleep stages were identified from EEG and neck EMG recordings. Breathing was measured using whole body plethysmography and blood pressure by telemetry. During non‐rapid eye movement sleep (nREM), unilateral photostimulation of C1 neurons produced arousal in 84 ± 4% of trials and sighs in 68 ± 7% of trials and increased respiratory frequency by 26 ± 5 bpm (n=5). During quiet awake states, C1 stimulation also caused sighs and increased breathing rate. This increase in breathing by C1 stimulation was occluded by hypoxia (12% O2), but not hypercapnia (6% CO2), despite the significantly higher basal ventilation under hypercapnia. This evidence suggests that the C1 neurons that activate breathing are themselves activated by hypoxia and drive the ventilatory response and arousal from sleep.Grant Funding Source: NIH (HL28785, HL74011)