Phenanthroline relaxes uterine contractions induced by diverse contractile agents by decreasing cytosolic calcium concentration

Uterine contractions during labor and preterm labor are influenced by a complex interplay of factors, including hormones and inflammatory mediators. This complexity may contribute to the limited efficacy of current tocolytics for preterm labor, a significant challenge in obstetrics with 15 million cases annually and approximately 1 million resulting deaths worldwide. We have previously shown that the myometrium expresses bitter taste receptors (TAS2Rs) and that their activation leads to uterine relaxation. Here, we investigated whether the selective TAS2R5 agonist phenanthroline can induce relaxation across a spectrum of human uterine contractions and whether the underlying mechanism involves changes in intracellular Ca2+ signaling. We performed experiments using samples from pregnant women undergoing scheduled cesarean delivery, assessing responses to various inflammatory mediators and oxytocin with and without phenanthroline. Our results showed that phenanthroline concentration-dependently inhibited contractions induced by PGF2α, U46619, 5-HT, endothelin-1 and oxytocin. Furthermore, in hTERT-infected human myometrial cells exposed to uterotonics, phenanthroline effectively suppressed the increase in intracellular Ca2+ concentration induced by PGF2α, U46619, oxytocin, and endothelin-1. These results suggest that the selective TAS2R5 agonist may not only significantly reduce uterine contractions but also decrease intracellular Ca2+ levels. This study highlights the potential development of TAS2R5 agonists as a new class of uterine relaxants, providing a novel avenue for improving the management of preterm labor.

Co-activation of Mas and pGCA receptors suppresses Endothelin-1-induced endothelial dysfunction via nitric oxide/cGMP system

BACKGROUND

The aortic endothelium is crucial in preserving vascular tone through endothelium-derived vasodilators and vasoconstrictors. Dysfunction in the endothelium is an early indicator of cardiovascular diseases. Our study explores the therapeutic potential of a dual-acting peptide (DAP) to co-activate Mas and pGCA receptors and restore the balance between vasodilators and vasoconstrictors on endothelial dysfunction in DOCA-salt-induced hypertensive rats.

METHODS

DOCA-salt was administered to male wistar rats to induce hypertension, and various parameters, including blood pressure (BP), water intake and body weight were monitored. DAP, Ang1-7, BNP, and losartan were administered to hypertensive rats for three weeks. Histological analysis and isometric tension studies were carried out to assess endothelial function. In addition to this, we used primary aortic endothelial cells for detailed mechanistic investigations.

RESULTS

DOCA-salt administration significantly elevated systolic, diastolic, mean arterial BP, and water intake whereas, downregulated the gene expression of Mas and pGCA receptors. However, DAP co-administration attenuated BP increase, upregulated the gene expression of Mas and pGCA receptors, normalized serum and urinary parameters, and effectively reduced fibrosis, inflammation, and vascular calcification. Notably, DAP outperformed the standard drug, Losartan. Our findings indicate that DAP restores aortic function by balancing the NO and ET1-induced pathways.

CONCLUSION

Co-activating Mas and pGCA receptors with DAP mitigates vascular damage and enhances endothelial function, emphasizing its potential to maintain a delicate balance between vasodilatory NO and vasoconstrictor ET1 in endothelial dysfunction.

Induced pluripotent stem cell derived pericytes respond to mediators of proliferation and contractility

BACKGROUND

Pericytes are multifunctional contractile cells that reside on capillaries. Pericytes are critical regulators of cerebral blood flow and blood-brain barrier function, and pericyte dysfunction may contribute to the pathophysiology of human neurological diseases including Alzheimers disease, multiple sclerosis, and stroke. Induced pluripotent stem cell (iPSC)-derived pericytes (iPericytes) are a promising tool for vascular research. However, it is unclear how iPericytes functionally compare to primary human brain vascular pericytes (HBVPs).

METHODS

We differentiated iPSCs into iPericytes of either the mesoderm or neural crest lineage using established protocols. We compared iPericyte and HBVP morphologies, quantified gene expression by qPCR and bulk RNA sequencing, and visualised pericyte protein markers by immunocytochemistry. To determine whether the gene expression of neural crest iPericytes, mesoderm iPericytes or HBVPs correlated with their functional characteristics in vitro, we quantified EdU incorporation following exposure to the key pericyte mitogen, platelet derived growth factor (PDGF)-BB and, contraction and relaxation in response to the vasoconstrictor endothelin-1 or vasodilator adenosine, respectively.

RESULTS

iPericytes were morphologically similar to HBVPs and expressed canonical pericyte markers. However, iPericytes had 1864 differentially expressed genes compared to HBVPs, while there were 797 genes differentially expressed between neural crest and mesoderm iPericytes. Consistent with the ability of HBVPs to respond to PDGF-BB signalling, PDGF-BB enhanced and a PDGF receptor-beta inhibitor impaired iPericyte proliferation. Administration of endothelin-1 led to iPericyte contraction and adenosine led to iPericyte relaxation, of a magnitude similar to the response evoked in HBVPs. We determined that neural crest iPericytes were less susceptible to PDGFR beta inhibition, but responded most robustly to vasoconstrictive mediators.

CONCLUSIONS

iPericytes express pericyte-associated genes and proteins and, exhibit an appropriate physiological response upon exposure to a key endogenous mitogen or vasoactive mediators. Therefore, the generation of functional iPericytes would be suitable for use in future investigations exploring pericyte function or dysfunction in neurological diseases.

RCOR1 improves neurobehaviors and neuron injury in rat cerebral palsy by Endothelin-1 targeting-induced Akt/GSK-3β pathway upregulation

BACKGROUND

RE1 Silencing Transcription factor (REST) corepressor 1 (RCOR1) has been reported to orchestrate neurogenesis, while its role in cerebral palsy (CP) remains elusive. Besides, RCOR1 can interact with Endothelin-1 (EDN1), and EDN1 expression is related to brain damage. Therefore, this study aimed to explore the effects of RCOR1/EDN1 on brain damage during the progression of CP.

METHODS

CP rats were established via hypoxia-ischemia insult, and injected with lentivirus-RCOR1, followed by examination of brain pathological conditions. The RCOR1 and EDN1 interaction was recognized using hTFtarget. Healthy rat cortical neuron cells received interference of RCOR1/EDN1 expression, and underwent oxygen-glucose deprivation/reoxygenation (OGD/R) treatment, after which phenotypic and molecular assays were conducted through the biochemical method, qRT-PCR and/or western blot.

RESULTS

RCOR1 was low-expressed but EDN1 was high-expressed in CP model rats and OGD/R-treated neurons. RCOR1 overexpression ameliorated rat neurobehaviors, alleviated brain pathological conditions, reduced TUNEL-positive cells, decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), increased superoxide dismutase (SOD) level and repressed EDN1 expression in the brains of CP model rats. In neurons, RCOR1 overexpression counteracted OGD/R-induced viability decrease, reduction of the levels of RCOR1, SOD, Bcl-2, caspase-3, p-Akt/Akt and p-GSK-3β/GSK-3β, and elevation of the levels of EDN1, ROS, Bax, and cleaved caspase-3, while EDN1 overexpression did contrarily on these events. Moreover, there was a negative interplay between RCOR1 overexpression and EDN1 overexpression in OGD/R-induced neurons.

CONCLUSION

RCOR1 ameliorates neurobehaviors and suppresses neuronal apoptosis and oxidative stress in CP through EDN1 targeting-mediated upregulation of Akt/GSK-3β.

Gestational intermittent hypoxia induces endothelial dysfunction and hypertension in pregnant rats: role of endothelin type B receptor†

Obstructive sleep apnea is a recognized risk factor for gestational hypertension, yet the exact mechanism behind this association remains unclear. Here, we tested the hypothesis that intermittent hypoxia, a hallmark of obstructive sleep apnea, induces gestational hypertension through perturbed endothelin-1 signaling. Pregnant Sprague-Dawley rats were subjected to normoxia (control), mild intermittent hypoxia (10.5% O2), or severe intermittent hypoxia (6.5% O2) from gestational days 10-21. Blood pressure was monitored. Plasma was collected and mesenteric arteries were isolated for myograph and protein analyses. The mild and severe intermittent hypoxia groups demonstrated elevated blood pressure, reduced plasma nitrate/nitrite, and unchanged endothelin-1 levels compared to the control group. Western blot analysis revealed decreased expression of endothelin type B receptor and phosphorylated endothelial nitric oxide synthase, while the levels of endothelin type A receptor and total endothelial nitric oxide synthase remained unchanged following intermittent hypoxia exposure. The contractile responses to potassium chloride, phenylephrine, and endothelin-1 were unaffected in endothelium-denuded arteries from mild and severe intermittent hypoxia rats. However, mild and severe intermittent hypoxia rats exhibited impaired endothelium-dependent vasorelaxation responses to endothelin type B receptor agonist IRL-1620 and acetylcholine compared to controls. Endothelium denudation abolished IRL-1620-induced vasorelaxation, supporting the involvement of endothelium in endothelin type B receptor-mediated relaxation. Treatment with IRL-1620 during intermittent hypoxia exposure significantly attenuated intermittent hypoxia-induced hypertension in pregnant rats. This was associated with elevated circulating nitrate/nitrite levels, enhanced endothelin type B receptor expression, increased endothelial nitric oxide synthase activation, and improved vasodilation responses. Our data suggested that intermittent hypoxia exposure during gestation increases blood pressure in pregnant rats by suppressing endothelin type B receptor-mediated signaling, providing a molecular mechanism linking intermittent hypoxia and gestational hypertension.

A ginger extract improves ocular blood flow in rats with endothelin-induced retinal blood flow dysfunction

The aim of this study was to investigate the effect of a ginger extract on optic nerve head blood flow (ONH BF) under endothelin-1 (ET-1) stimulation. Using laser speckle flowgraphy, we measured ONH BF in brown Norway rats. To establish the ONH BF impairment profile under ET-1 stimulation, we administered an intravitreal injection of ET-1 under anesthesia. We then gave the ginger extract sublingually to assess its effect on ONH BF in both normal and ET-1-induced ischemic conditions. Post ET-1 injection, there were no significant changes in parameters including intraocular pressure or systemic factors. ONH BF showed a dose-dependent decline after ET-1 injection, with a significant reduction after a 2.50 pmol ET-1 dose. Sublingual administration of the ginger extract significantly improved ONH BF in both normal and ET-1-stimulated rats. This suggests that our newly developed supplement for improving ONH BF has a potential role in retinal ischemic diseases, including glaucoma.

Endothelin-1 acutely increases nitric oxide production via the calcineurin mediated dephosphorylation of Caveolin-1

Endothelin (ET)-1 is an endothelial-derived peptide that exerts biphasic effects on nitric oxide (NO) levels in endothelial cells such that acute exposure stimulates-while sustained exposure attenuates-NO production. Although the mechanism involved in the decrease in NO generation has been identified but the signaling involved in the acute increase in NO is still unresolved. This was the focus of this study. Our data indicate that exposing pulmonary arterial endothelial cells (PAEC) to ET-1 led to an increase in NO for up to 30min after which levels declined. These effects were attenuated by ET receptor antagonists. The increase in NO correlated with significant increases in pp60Src activity and increases in eNOS phosphorylation at Tyr83 and Ser1177. The ET-1 mediated increase in phosphorylation and NO generation were attenuated by the over-expression of a pp60Src dominant negative mutant. The increase in pp60Src activity correlated with a reduction in the interaction of Caveolin-1 with pp60Src and the calcineurin-mediated dephosphorylation of caveolin-1 at three previously unidentified sites: Thr91, Thr93, and Thr95. The calcineurin inhibitor, Tacrolimus, attenuated the acute increase in pp60Src activity induced by ET-1 and a calcineurin siRNA attenuated the ET-1 mediated increase in eNOS phosphorylation at Tyr83 and Ser1177 as well as the increase in NO. By using a Caveolin-1 celluSpot peptide array, we identified a peptide targeting a sequence located between aa 41-56 as the pp60Src binding region. This peptide fused to the TAT sequence was found to decrease caveolin-pp60Src interaction, increased pp60Src activity, increased eNOS pSer1177 and NO levels in PAEC and induce vasodilation in isolated aortic rings in wildtype but not eNOS knockout mice. Together, our data identify a novel mechanism by which ET-1 acutely increases NO via a calcineurin-mediated dephosphorylation of caveolin-1 and the subsequent stimulation of pp60Src activity, leading to increases in phosphorylation of eNOS at Tyr83 and Ser1177.

Calcium handling coupled to the endothelin ETA and ETB receptor-mediated vasoconstriction in resistance arteries: Differential regulation by PI3K, PKC and RhoK

Abnormal endothelin-1 (ET-1) activity is involved in the pathogenesis of vascular diseases such as essential and pulmonary arterial hypertension, coronary artery disease, and cerebrovascular disease, blockade of ET receptors having shown efficacy in clinical assays and experimental models of hypertension. Augmented Ca2+ influx and changes in Ca2+ sensitization associated with arterial vasoconstriction underlie increased systemic vascular resistance in hypertension. Since peripheral resistance arteries play a key role in blood pressure regulation, we aimed to determine here the specific Ca2+ signaling mechanisms linked to the ET receptor-mediated vasoconstriction in resistance arteries and their selective regulation by protein kinase C (PKC), Rho kinase (RhoK), the phosphatidylinositol 3-kinase (PI3K) and the mitogen-activated protein kinase (MAPK). ET-1-induced contraction was mediated by the endothelin ETA receptor with a minor contribution of vascular smooth muscle (VSM) endothelin ETB receptors. ET receptor activation elicited Ca2+ mobilization from intracellular stores, extracellular Ca2+ influx and Ca2+ sensitization associated with contraction in resistance arteries. Vasoconstriction induced by ET-1 was largely dependent on activation of canonical transient receptor potential channel 3 (TRPC3) and extracellular Ca2+ influx through nifedipine-sensitive voltage-dependent Ca2+ channels. PI3K inhibition reduced intracellular Ca2+ mobilization and Ca2+ entry without altering vasoconstriction elicited by ET-1, while PKC has dual opposite actions by enhancing Ca2+ influx associated with contraction, and by inhibiting Ca2+ release from intracellular stores. RhoK was a major determinant of the enhanced sensitivity of the contractile filaments underlying ET-1 vasoconstriction, with also a modulatory positive action on Ca2+ influx and intracellular Ca2+ release. Augmented RhoK and PKC activities are involved in vascular dysfunction in hypertension and vascular complications of insulin-resistant states, and these kinases are thus potential pharmacological targets in vascular diseases in which the ET pathway is impaired.

Long-Term Effects on Retinal Structure and Function in a Mouse Endothelin-1 Model of Retinal Ganglion Cell Degeneration

Purpose

To study the long-term effects of endothelin-1 (ET-1)-induced retinal pathologies in mouse, using clinically relevant tools.

Methods

Adult C57BL/6 mice (7-9 weeks old) were intravitreally injected with PBS (n = 10) or 0.25 (n = 8), 0.5 (n = 8), or 1 nmol ET-1 (n = 9) and examined using electroretinogram, optical coherence tomography (OCT), and Doppler OCT at baseline and postinjection days 10, 28, and 56. Retinal ganglion cell (RGC) survival in retinal whole mount was quantified at days 28 and 56.

Results

ET-1 induced immediate retinal arterial constriction. The significantly reduced total blood flow and positive scotopic threshold response in the 0.5- and 1-nmol ET-1 groups at day 10 were recovered at day 28. A-wave magnitude was also significantly reduced at days 10 and 28. While a comparable and significant reduction in retinal nerve fiber layer thickness was detected in all ET-1 groups at day 56, the 1-nmol group was the earliest to develop such change at day 28. All ET-1 groups showed a transient inner retinal layer thinning at days 10 and 28 and a plateaued outer layer thickness at days 10 to 56. The 1-nmol group showed a significant RGC loss over all retinal locations examined at day 28 as compared with PBS control. As for the lower-dosage groups, significant RGC density loss at central and midperipheral retina was detected at day 56 when compared with day 28.

Conclusions

ET-1 injection in mice resulted in a transient vascular constriction and reduction in retinal functions, as well as a gradual loss of retinal nerve fiber layer and RGC in a dose-dependent manner.

Role of Brain Endothelin Receptor Type B (ETB) in the Regulation of Tyrosine Hydroxylase in the Olfactory Bulb of DOCA-Salt Hypertensive Rats

BACKGROUND

We previously reported that endothelins (ETs) regulate tyrosine hydroxylase (TH) activity and expression in the olfactory bulb (OB) of normotensive and hypertensive animals. Applying an ET receptor type A (ETA) antagonist to the brain suggested that endogenous ETs bind to ET receptor type B (ETB) to elicit effects.

OBJECTIVE

The aim of the present work was to evaluate the role of central ETB stimulation on the regulation of blood pressure (BP) and the catecholaminergic system in the OB of deoxycorticosterone acetate (DOCA)-salt hypertensive rats.

METHODS

DOCA-salt hypertensive rats were infused for 7 days with cerebrospinal fluid or IRL-1620 (ETB receptor agonist) through a cannula placed in the lateral brain ventricle. Systolic BP (SBP) and heart rate were recorded by plethysmography. The expression of TH and its phosphorylated forms in the OB were determined by immunoblotting, TH activity by a radioenzymatic assay, and TH mRNA by quantitative real-time polymerase chain reaction.

RESULTS

Chronic administration of IRL-1620 decreased SBP in hypertensive rats but not in normotensive animals. Furthermore, the blockade of ETB receptors also decreased TH-mRNA in DOCA-salt rats, but it did not modify TH activity or protein expression.

CONCLUSION

These findings suggest that brain ETs through the activation of ETB receptors contribute to SBP regulation in DOCA-salt hypertension. However, the catecholaminergic system in the OB does not appear to be conclusively involved although mRNA TH was reduced. Present and previous findings suggest that in this salt-sensitive animal model of hypertension, the OB contributes to chronic BP elevation.

Release of 6-nitrodopamine modulates vascular reactivity of Pantherophis guttatus aortic rings

6-Nitrodopamine (6-ND) is a novel catecholamine that is released from human umbilical cord vessels and Chelonoidis carbonaria aortic rings. The synthesis/release of 6-ND is inhibited by either pre-incubation of the vessels with the nitric oxide (NO) synthase inhibitor L-NAME or by mechanical removal of the endothelium. 6-ND causes powerful vasorelaxation, acting as a potent and selective dopamine D₂-like receptor antagonist. Basal release of 6-ND from Panterophis guttatus endothelium intact and denuded aortic rings was quantified by LC-MS/MS. In order to evaluate the interaction of 6-ND with other catecholamines, aortic rings were suspended vertically between two metal hooks in 10-mL organ baths containing Krebs-Henseleit's solution and attached to isometric transducers. Endothelium intact aortic rings presented basal release of 6-ND, which was significantly reduced by previous incubation with L-NAME (100 μM). In endothelin-1 (3 nM) pre-contracted endothelium intact aortic rings, 6-ND (10pM-1 μM) and the dopamine D₂-receptor antagonist L-761,626 (10 pM-1 μM) induced concentration-dependent relaxations, which were not affected by incubation with L-NAME but greatly reduced in endothelium-removed aortic rings. 6-ND (0.1-1 μM) produced significant rightward shifts of the concentration-response curves to dopamine in L-NAME pre-treated endothelium-intact (pA₂ 7.01) rings. Contractions induced by noradrenaline and adrenaline were not affected by pre-incubation with 6-ND (1 μM). The EFS-induced contractions of L-NAME pre-treated endothelium-intact aortic rings were significantly inhibited by incubation with 6-ND (1 μM). The results indicate that 6-ND released from Pantherophis guttatus aortic rings is coupled to NO release and represents a new mechanism by which NO can modulate vascular reactivity independently of cGMP production.

Role of endothelin in the pathophysiology of migraine: A new view on an old player

There is cumulating evidence that endothelin-1 (ET-1) may play a role in migraine, however controversial findings still impede a conclusion to be drawn. Herein we tested the hypothesis that endothelin ETB receptors are major contributors to migraine-like responses. ET-1, IRL-1620 (selective ETB receptor agonist) or CGRP were injected into the trigeminal ganglion (TG) of female Wistar rats, and the development of periorbital mechanical allodynia was assessed hourly with von Frey hairs. Twenty-four hours later, rats were exposed to an aversive light for 1 h, after which the reactivation of periorbital mechanical allodynia (indicating photic sensitivity) was assessed up to 4 h. Moreover, the effect of systemic Bosentan (ETA/ETB receptors antagonist) or the selective antagonists of ETA (BQ-123) and ETB (BQ-788) receptors injected into the TG were evaluated against CGRP-induced responses. ET-1 and IRL-1620 injection into the TG induced periorbital mechanical allodynia and photic sensitivity. Bosentan attenuated periorbital mechanical allodynia but failed to affect photic sensitivity induced by CGRP. Selective blockade of ETB receptors in the TG fully prevented the development of periorbital mechanical allodynia and photic sensitivity induced by CGRP, but ETA receptor blockade caused only a slight reduction of periorbital mechanical allodynia without affecting photic sensitivity. ETB receptor-operated mechanisms in the TG may contribute to migraine-like responses in female rats.

UV-B filter octylmethoxycinnamate-induced vascular endothelial disruption on rat aorta: In silico and in vitro approach

Throughout human life, an extensive and varied range of emerging environmental contaminants, called endocrine disruptors (EDCs), cause adverse health effects, including in the cardiovascular (CV) system. Cardiovascular diseases (CVD) are worryingly one of the leading causes of all mortality and mobility worldwide. The UV-B filter octylmethoxycinnamate (also designated octinoxate, or ethylhexyl methoxycinnamate (CAS number: 5466-77-3)) is an EDC widely present in all personal care products. However, to date, there are no studies evaluating the OMC-induced effects on vasculature using animal models to improve human cardiovascular health. This work analysed the effects of OMC on rat aorta vasculature and explored the modes of action implicated in these effects. Our results indicated that OMC relaxes the rat aorta by endothelium-dependent mechanisms through the signaling pathways of cyclic nucleotides and by endothelium-independent mechanisms involving inhibition of L-Type voltage-operated Ca²⁺ channels (L-Type VOCC). Overall, OMC toxicity on rat aorta may produce hypotension via vasodilation due to excessive NO release and blockade of L-Type VOCC. Moreover, the OMC-induced endothelial dysfunction may also occur by promoting the endothelial release of endothelin-1. Therefore, our findings demonstrate that exposure to OMC alters the reactivity of the rat aorta and highlight that long-term OMC exposure may increase the risk of human CV diseases.

Salt, Not Always a Cardiovascular Enemy? A Mini-Review and Modern Perspective

Dietary salt intake is a long-debated issue. Increased sodium intake is associated with high blood pressure, leading to salt-sensitive hypertension. Excessive salt intake leads to arterial stiffness in susceptible individuals via impaired nitric oxide action and increased endothelin-1 expression, overactivity of the renal sympathetic nervous system and also via aldosterone-independent activation of the mineralocorticoid receptor. Salt restriction in such individuals reduces blood pressure (BP) values. The optimal level of salt restriction that leads to improved cardiovascular outcomes is still under debate. Current BP and dietary guidelines recommend low sodium intake for the general population. However, a specific category of patients does not develop arterial hypertension in response to sodium loading. In addition, recent research demonstrates the deleterious effects of aggressive sodium restriction, even in heart failure patients. This mini review discusses current literature data regarding the advantages and disadvantages of salt restriction and how it impacts the overall health status.

Histone Deacetylase 6 Inhibitor JS28 Prevents Pathological Gene Expression in Cardiac Myocytes

Background Epigenetic modulators have been proposed as promising new drug targets to treat adverse remodeling in heart failure. Here, we evaluated the potential of 4 epigenetic drugs, including the recently developed histone deacetylase 6 (HDAC6) inhibitor JS28, to prevent endothelin-1 induced pathological gene expression in cardiac myocytes and analyzed the chromatin binding profile of the respective inhibitor targets. Methods and Results Cardiac myocytes were differentiated and puromycin-selected from mouse embryonic stem cells and treated with endothelin-1 to induce pathological gene expression (938 differentially expressed genes, q<0.05). Dysregulation of gene expression was at least in part prevented by epigenetic inhibitors, including the pan-BRD (bromodomain-containing protein) inhibitor bromosporine (290/938 genes), the BET (bromodomain and extraterminal) inhibitor JQ1 (288/938), the broad-spectrum HDAC inhibitor suberoylanilide hydroxamic acid (227/938), and the HDAC6 inhibitor JS28 (210/938). Although the 4 compounds were similarly effective toward pathological gene expression, JS28 demonstrated the least adverse effects on physiological gene expression. Genome-wide chromatin binding profiles revealed that HDAC6 binding sites were preferentially associated with promoters of genes involved in RNA processing. In contrast, BRD4 binding was associated with genes involved in core cardiac myocyte functions, for example, myocyte contractility, and showed enrichment at enhancers and intronic regions. These distinct chromatin binding profiles of HDAC6 and BRD4 might explain the different effects of their inhibitors on pathological versus physiological gene expression. Conclusions In summary, we demonstrated, that the HDAC6 inhibitor JS28 effectively prevented the adverse effects of endothelin-1 on gene expression with minor impact on physiological gene expression in cardiac myocytes. Selective HDAC6 inhibition by JS28 appears to be a promising strategy for future evaluation in vivo and potential translation into clinical application.

Acute cardiovascular effects of inhaled ambient particulate matter: Chemical composition-related oxidative stress, endothelin-1, blood pressure, and ST-segment changes in Wistar rats

Short-term increases in particulate matter (PM) are associated with heightened morbidity and mortality from cardiovascular causes. Inhalation of PM is known to increase endothelin (ET)-1 levels. Yet, less is known about particle composition-related changes at the molecular level including the endothelinergic system and relationship with cardiovascular function changes. In this work, adult Wistar male rats were exposed for 4 h by nose-only inhalation to clean air, Ottawa urban particles (EHC-93, 48 mg/m³) and water-leached (EHC-93L, 49 mg/m³) particles, to examine the effect of particle compositional changes on oxidative stress, circulating ETs, blood pressure, and heart electrophysiology. Particle deposition in the respiratory compartment was estimated at 85 μg (25 ng/cm²). Lung cell proliferation was low in both treatment groups, indicating absence of acute injury. Inhalation of EHC-93 caused statistically significant elevations (p < 0.05) of oxidative stress markers, ET-1, ET-3, blood pressure, and a decrease of ST-segment duration in the ECG at 1.5 days post-exposure. Leached particles (EHC-93L) caused rapid but transient elevation (p < 0.05) of oxidative stress, ET-1, ET-2, and ET-3 at earlier time points, with no changes in blood pressure or ST-segment. These results demonstrate that inhalation of urban particles at an internal dose inadequate to cause acute lung injury can induce oxidative stress, enhance vasoactive endothelins, leading to vasopressor response, affecting cardiac electrophysiology in Wistar rats, consistent with the cardiovascular impacts of ambient particles in human populations. Change in particle potency after removal of soluble species, notably cadmium, zinc and polar organics suggests that the toxicodynamics of cardiovascular effects can be modified by physicochemical properties of particles.

Effects of systemic and renal intramedullary endothelin-1 receptor blockade on tissue NO and intrarenal hemodynamics in normotensive and hypertensive rats

Endothelin 1 (ET-1) seems essential in salt-dependent hypertension, and activation of ETA receptors causes renal vasoconstriction. However, the response in the renal medulla and the role of tissue NO availability has never been adequately explored in vivo. We examined effects of ETA and ETB receptor blockade (atrasentan and BQ788) on blood pressure (MAP), medullary blood flow (MBF) and medullary tissue NO. Effects of systemic and intramedullary blocker application were compared in anesthetized normotensive ET-1-pretreated Sprague-Dawley rats (S-D), in salt-dependent hypertension (HS/UNX) and in spontaneously hypertensive rats (SHR). Total renal blood flow (RBF) was measured using a Transonic renal artery probe, MBF as laser-Doppler flux, and tissue NO signal using selective electrodes. In normotensive rats ET-1 significantly increased MAP, decreased RBF (-20%) and renal medullary NO. In HS/UNX rats atrasentan decreased MAP and increased medullary NO, earlier and more profoundly with intravenous infusion. In SHR atrasentan decreased MAP, more effectively with intravenous infusion; the increase in tissue NO (∼10%) was similar with both routes; however, only intramedullary atrasentan increased MBF. No consistent responses to BQ788 were seen. We confirmed dominant role of ETA receptors in regulation of blood pressure and renal hemodynamics in normotensive and hypertensive rats and provided novel evidence for the role of ETA in control of intrarenal NO bioavailability in salt-dependent and spontaneous hypertension. Under conditions of activation of the endothelin system ETB stimulation preserved medullary perfusion.

Contributions of Sodium-Hydrogen Exchanger 1 and Mitogen-Activated Protein Kinases to Enhanced Retinal Venular Constriction to Endothelin-1 in Diabetes

Diabetes elevates endothelin-1 (ET-1) in the vitreous and enhances constriction of retinal venules to this peptide. However, mechanisms contributing to ET-1-induced constriction of retinal venules are incompletely understood. We examined roles of sodium-hydrogen exchanger 1 (NHE1), protein kinase C (PKC), mitogen-activated protein kinases (MAPKs), and extracellular calcium (Ca²⁺) in retinal venular constriction to ET-1 and the impact of diabetes on these signaling molecules. Retinal venules were isolated from control pigs and pigs with streptozocin-induced diabetes for in vitro studies. ET-1-induced vasoconstriction was abolished in the absence of extracellular Ca²⁺ and sensitive to c-Jun N-terminal kinase (JNK) inhibitor SP600125 but unaffected by extracellular signal-regulated kinase (ERK) inhibitor PD98059, p38 kinase inhibitor SB203580, or broad-spectrum PKC inhibitor Gö 6983. Diabetes (after 2 weeks) enhanced venular constriction to ET-1, which was insensitive to PD98059 and Gö 6983 but was prevented by NHE1 inhibitor cariporide, SB203580, and SP600125. In conclusion, extracellular Ca²⁺ entry and activation of JNK, independent of ERK and PKC, mediate constriction of retinal venules to ET-1. Diabetes activates p38 MAPK and NHE1, which cause enhanced venular constriction to ET-1. Treatments targeting these vascular molecules may lessen retinal complications in early diabetes.

Modulation of vascular contraction via soluble guanylate cyclase signaling in a novel ex vivo method using rat precision-cut liver slices

Fibrotic processes in the liver of non-alcoholic steatohepatitis (NASH) patients cause microcirculatory dysfunction in the organ which increases blood vessel resistance and causes portal hypertension. Assessing blood vessel function in the liver is challenging, necessitating the development of novel methods in normal and fibrotic tissue that allow for drug screening and translation toward pre-clinical settings. Cultures of precision cut liver slices (PCLS) from normal and fibrotic rat livers were used for blood vessel function analysis. Live recording of vessel diameter was used to assess the response to endothelin-1, serotonin and soluble guanylate cyclase (sGC) activation. A cascade of contraction and relaxation events in response to serotonin, endothelin-1, Ketanserin and sGC activity could be established using vessel diameter analysis of rat PCLS. Both the sGC activator BI 703704 and the sGC stimulator Riociguat prevented serotonin-induced contraction in PCLS from naive rats. By contrast, PCLS cultures from the rat CCl4 NASH model were only responsive to the sGC activator, thus establishing that the sGC enzyme is rendered non-responsive to nitric oxide under oxidative stress found in fibrotic livers. The role of the sGC pathway for vessel relaxation of fibrotic liver tissue was identified in our model. The obtained data shows that the inhibitory capacities on vessel contraction of sGC compounds can be translated to published preclinical data. Altogether, this novel ex vivo PCLS method allows for the differentiation of drug candidates and the translation of therapeutic approaches towards the clinical use.

Down-regulation of astrocytic sonic hedgehog by activation of endothelin ETB receptors: Involvement in traumatic brain injury-induced disruption of blood brain barrier in a mouse model

In the adult brain, sonic hedgehog acts on cerebral microvascular endothelial cells to stabilize the blood-brain barrier. The expression of sonic hedgehog by astrocytes is altered during brain injury, and this change has been shown to affect permeability of blood-brain barrier. However, much remains unknown about the regulation of astrocytic sonic hedgehog production. Our results showed that endothelin-1 reduced sonic hedgehog mRNA expression and extracellular protein release in mouse cerebral cultured astrocytes, but had no effect in bEnd.3, a mouse brain microvascular endothelial-derived cell line. The effect of endothelin-1 on astrocyte sonic hedgehog expression was suppressed by an ET_B antagonist BQ788, but was unchanged by the ET_A antagonist FR139317. In cultured astrocytes and bEnd.3, endothelin-1 did not affect the expression of the sonic hedgehog receptor-related molecules, patched-1 and smoothened. In an animal model of traumatic brain injury, fluid percussion injury on the mouse cerebrum increased the expression of sonic hedgehog, patched-1, and smoothened. Repeated administration of BQ788 enhanced sonic hedgehog expression at 5 days after fluid percussion injury. Histochemical examination revealed sonic hedgehog expression in glial fibrillary acidic protein-positive astrocytes in the cerebrum after fluid percussion injury. Administration of exogenous sonic hedgehog and BQ788 suppressed Evans blue extravasation, an indicator of blood vessel permeability, induced by fluid percussion injury. The effects of BQ788 on fluid percussion injury-induced Evans blue extravasation were reduced by the administration of jervine, a sonic hedgehog inhibitor. Altogether, these results suggest that endothelin-1 down-regulates astrocytic sonic hedgehog to promote disruption of the blood-brain barrier during traumatic brain injury.

Endothelin-1 drives invadopodia and interaction with mesothelial cells through ILK

Cancer cells use actin-based membrane protrusions, invadopodia, to degrade stroma and invade. In serous ovarian cancer (SOC), the endothelin A receptor (ETAR) drives invadopodia by a not fully explored coordinated function of β-arrestin1 (β-arr1). Here, we report that β-arr1 links the integrin-linked kinase (ILK)/βPIX complex to activate Rac3 GTPase, acting as a central node in the adhesion-based extracellular matrix (ECM) sensing and degradation. Downstream, Rac3 phosphorylates PAK1 and cofilin and promotes invadopodium-dependent ECM proteolysis and invasion. Furthermore, ETAR/ILK/Rac3 signaling supports the communication between cancer and mesothelial cells, favoring SOC cell adhesion and transmigration. In vivo, ambrisentan, an ETAR antagonist, inhibits the adhesion and spreading of tumor cells to intraperitoneal organs, and invadopodium marker expression. As prognostic factors, high EDNRA/ILK expression correlates with poor SOC clinical outcome. These findings provide a framework for the ET-1R/β-arr1 pathway as an integrator of ILK/Rac3-dependent adhesive and proteolytic signaling to invadopodia, favoring cancer/stroma interactions and metastatic behavior.

Coupling of store-operated calcium entry to vasoconstriction is acid-sensing ion channel 1a dependent in pulmonary but not mesenteric arteries

Although voltage-gated Ca²⁺ channels (VGCC) are a major Ca²⁺ entry pathway in vascular smooth muscle cells (VSMCs), several other Ca²⁺-influx mechanisms exist and play important roles in vasoreactivity. One of these is store-operated Ca²⁺ entry (SOCE), mediated by an interaction between STIM1 and Orai1. Although SOCE is an important mechanism of Ca²⁺ influx in non-excitable cells (cells that lack VGCC); there is debate regarding the contribution of SOCE to regulate VSMC contractility and the molecular components involved. Our previous data suggest acid-sensing ion channel 1a (ASIC1a) is a necessary component of SOCE and vasoconstriction in small pulmonary arteries. However, it is unclear if ASIC1a similarly contributes to SOCE and vascular reactivity in systemic arteries. Considering the established role of Orai1 in mediating SOCE in the systemic circulation, we hypothesize the involvement of ASIC1a in SOCE and resultant vasoconstriction is unique to the pulmonary circulation. To test this hypothesis, we examined the roles of Orai1 and ASIC1a in SOCE- and endothelin-1 (ET-1)-induced vasoconstriction in small pulmonary and mesenteric arteries. We found SOCE is coupled to vasoconstriction in pulmonary arteries but not mesenteric arteries. In pulmonary arteries, inhibition of ASIC1a but not Orai1 attenuated SOCE- and ET-1-induced vasoconstriction. However, neither inhibition of ASIC1a nor Orai1 altered ET-1-induced vasoconstriction in mesenteric arteries. We conclude that SOCE plays an important role in pulmonary, but not mesenteric, vascular reactivity. Furthermore, in contrast to the established role of Orai1 in SOCE in non-excitable cells, the SOCE response in pulmonary VSMCs is largely mediated by ASIC1a.

Store-operated Ca2+ entry in primary murine lung fibroblasts is independent of classical transient receptor potential (TRPC) channels and contributes to cell migration

Stromal interaction molecules (STIM1, 2) are acting as sensors for Ca2+ in intracellular stores and activate Orai channels at the plasma membrane for store-operated Ca2+ entry (SOCE), while classical transient receptor potential (TRPC) channel mediate receptor-operated Ca2+ entry (ROCE). Several reports, however, indicate a role for TRPC in SOCE in certain cell types. Here, we analyzed Ca2+ influx and cell function in TRPC1/6-deficient (TRPC1/6-/-) and STIM1/2- deficient (STIM1/2ΔpmLF) primary murine lung fibroblasts (pmLF). As expected, SOCE was decreased in STIM1/2- deficient pmLF and ROCE was decreased in TRPC1/6-/- pmLF compared to control cells. By contrast, SOCE was not significantly different in TRPC1/6-/- pmLF and ROCE was similar in STIM1/2-deficient pmLF compared to Wt cells. Most interestingly, cell proliferation, migration and nuclear localization of nuclear factor of activated T-cells (NFATc1 and c3) were decreased after ablation of STIM1/2 proteins in pmLF. In conclusion, TRPC1/6 channels are not involved in SOCE and STIM1/2 deficiency resulted in decreased cell proliferation and migration in pmLF.

Sex differences in vascular reactivity of coronary artery bypass graft conduits

Females have increase in-hospital mortality and poorer outcomes following coronary artery bypass grafting (CABG). Biological differences in the reactivity of the graft conduits to circulating catecholamine may contribute to this sex difference. This study examined sex differences in the vasoconstrictor responses of internal mammary artery (IMA) and saphenous vein (SV) conduits to phenylephrine (PE) and endothelin-1 (ET-1). Functional IMA and SV were obtained from 78 male and 50 female patients undergoing CABG (67.7 ± 11 and 69 ± 10 years, respectively) and subjected to the following experimental conditions. (1) Concentration response curves for PE and ET-1 were generated in an intact IMA and SV and endothelium denuded IMA segments, (2) in the presence of the nitric oxide synthase inhibitor (L-NAME) or the cyclooxygenase inhibitor (indomethacin) in an endothelium-intact IMA and (3) the activity state (abundance and phosphorylation) of the α1-adrenergic receptor was investigated using Phos-tag™ western blot analysis. (1) Compared to male, female IMA and SV were hypersensitive to PE but not ET-1 (p < 0.05). The female IMA hypersensitivity response to PE was abolished following endothelial denudation, (2) persisted in the presence of L-NAME but was abolished in the presence of indomethacin and (3) there was no sex differences in the abundance and phosphorylation of the α1-adrenergic receptor in IMA. Female IMA and SV graft conduits are hypersensitive to α1-adrenergic stimuli. This endothelial cyclooxygenase pathway-mediated hypersensitivity may produce excessive IMA and SV graft constriction in females administered catecholamines and could contribute to their poorer CABG outcomes.

Efficacy of a Novel ACE-Inhibitory Peptide from Sargassum Maclurei in Hypertension and Reduction of Intracellular Endothelin-1

Sargassum maclurei is a potential protein resource because of its high protein content and relatively balanced amino acid composition. To promote its usage in food, medical, or other industries, S. maclurei protein was hydrolyzed by pepsin and papain to obtain bioactive peptides. The S. maclurei protein hydrolysates (SMPHs) were purified using gel chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), and 12 major fractions were obtained. The fraction D11 with the highest angiotensin I-converting enzyme (ACE) inhibition (61.59%, at 1 mg/ mL) was subjected to liquid chromatography-mass spectrometry (LC-MS/MS) analysis, and about 17 peptides were identified, of which the RWDISQPY (1063.5 Da) was chosen to be synthesized based on in silico analysis. The RWDISQPY demonstrated high ACE inhibition ability (IC50: 72.24 μM) with competitive inhibition mode, and could effectively (p < 0.05) lower the systolic blood pressure and diastolic pressure of spontaneously hypertensive rats at the concentration of 150 mg/kg body weight. The results of the molecular docking simulation demonstrated that RWDISQPY could bind with the active sites S1 and S2 of ACE via short hydrogen bonds. Moreover, RWDISQPY showed acceptable endothelin-1 suppressing capacity (26.21% at 1.5 mg/mL). These results indicate that S. maclurei could be developed into functional foods such as antihypertensive products.

Endothelin B Receptor is Involved in Endothelin-1 Induced Cell Response in Vascular Smooth Muscle Cells

Cardiovascular disease is an important problem in developed countries and the effective target of treatment should be further developed. ET_B receptor is one of receptor of ET system, which may affect the function of vascular smooth muscle cell via NO released. In order to clarify the theory, we had cell culture with or without ET-1 treatment. Flow cytometry had been used to prove cell apoptosis and transwell assay had been used to detect the ability of cell migration. The expression of ET-1, ICAM-1, VCAM-1, MMP-9 and CRP were detected by using qRT-PCR and Western blot assay. After we had found that RES-701-1 one of ET_B receptor antagonists can induced VSMC apoptosis and migration. Also RES-701-1 can down regulated ICAM-1, VCAM-1, MMP-9 and CRP while ET-1 was the opposite. In a conclusion ET_B receptor is one of the role target to mediate vascular smooth muscle cell through the ET system and it may be a significant treating target in cardiovascular disease in the future.

Endothelin-1 induces a strong pressor effect in ball pythons (Python regius)

Endothelin-1 (ET-1) is a very potent vasoactive peptide released from endothelial cells, and ET-1 plays an important role in the maintenance and regulation of blood pressure in mammals. ET-1 signaling is mediated by two receptors: ET_A and ET_B. In mammals, ET_A receptors are located on vascular smooth muscle where they mediate vasoconstriction. ET_B receptors located on the endothelium mediate vasodilatation through the release of nitric oxide, whereas stimulation of ET_B receptors placed on vascular smooth muscle leads to vasoconstriction. Less is known about ET-1 signaling in reptiles. In anaesthetized alligators, ET-1 elicits a biphasic blood pressure with a long-lasting initial decrease followed by a smaller increase in systemic blood pressure. In anaesthetized freshwater turtles, ET-1 causes a dose-dependent systemic vasodilatation mediated through ET_B receptors. In the present study, we investigated the cardiovascular effects of ET-1 on the systemic and pulmonary vasculature of pythons. The presence of ET_A and ET_B receptors in the vasculature of pythons was verified by means of immunoblotting. Myography on isolated vessels revealed a dose-dependent vasoconstrictory response to ET-1 in both mesenteric and pulmonary arteries. Pressure measurements in recovered specimens revealed an ET-1-induced rise in systemic blood pressure supporting our in vitro findings. In conclusion, our study shows that ET-1 induces a strong pressor effect in the systemic circulation.

The effects of extended nitric oxide release on responses of the human non-pregnant myometrium to endothelin-1 or vasopressin

BACKGROUND

Uterotonic mediators: endothelin-1 (ET-1), arginine vasopressin (AVP), and nitric oxide (NO) play important roles in the regulation of uterine contractility. We hypothesize that NO affects both ET-1 or AVP. Therefore, this study investigated the involvement of extended exogenous NO release in the regulation of responses of the human non-pregnant myometrium to ET-1 and AVP.

METHODS

Specimens were obtained from 10 premenopausal women, undergoing hysterectomy for benign gynecological disorders. Responses of the myometrial strips to ET-1 or AVP in the absence and presence of an exogenous NO donor (diethylenetriamine; DETA/NO; 10-4 mol/L) were recorded under isometric conditions. To inhibit endogenous NO, a competitive inhibitor of NO synthase, L-NG-nitroarginine (L-NNA) was added to the organ bath.

RESULTS

ET-1 enhanced the spontaneous contractile activity of the myometrium more powerfully (p < 0.01) than AVP. Preincubation with exogenous NO weakened ET-1- or AVP-induced increases in this contractile activity (p < 0.05). However, unexpected results were obtained after preincubation with L-NNA and with DETA/NO then added. Both ET-1 and AVP induced augmented contractile effects in almost all concentrations compared with the responses to these peptides alone or after NOS synthase inhibition (both p < 0.01).

CONCLUSIONS

This study demonstrated for the first time that extended incubation with a NO donor influences the uterine muscle response evoked by ET-1 and AVP. Both endogenous and exogenous NO is involved in the control of the uterine responses to ET-1 or AVP of non-pregnant myometrium. Furthermore, both peptides stimulate increased uterine contractility when the local imbalance between the constrictive and relaxing mediators takes place.

Hypertrophy of human embryonic stem cell-derived cardiomyocytes supported by positive feedback between Ca2+ and diacylglycerol signals

Human embryonic stem cell-derived cardiomyocytes develop pronounced hypertrophy in response to angiotensin-2, endothelin-1, and a selected mix of three fatty acids. All three of these responses are accompanied by increases in both basal cytoplasmic Ca2+ and diacylglycerol, quantified with the Ca2+ sensor Fluo-4 and a FRET-based diacylglycerol sensor expressed in these cardiomyocytes. The heart glycoside, ouabain (30 nM), and a recently developed inhibitor of diacylglycerol lipases, DO34 (1 μM), cause similar hypertrophy responses, and both responses are accompanied by equivalent increases of basal Ca2+ and diacylglycerol. These results together suggest that basal Ca2+ and diacylglycerol form a positive feedback signaling loop that promotes execution of cardiac growth programs in these human myocytes. Given that basal Ca2+ in myocytes depends strongly on the Na+ gradient, we also tested whether nanomolar ouabain concentrations might stimulate Na+/K+ pumps, as described by others, and thereby prevent hypertrophy. However, stimulatory effects of nanomolar ouabain (1.5 nM) were not verified on Na+/K+ pump currents in stem cell-derived myocytes, nor did nanomolar ouabain block hypertrophy induced by endothelin-1. Thus, low-dose ouabain is not a "protective" intervention under the conditions of these experiments in this human myocyte model. To summarize, the major aim of this study has been to characterize the progression of hypertrophy in human embryonic stem cell-derived cardiac myocytes in dependence on diacylglycerol and Na+ gradient changes, developing a case that positive feedback coupling between these mechanisms plays an important role in the initiation of hypertrophy programs.

A model of guided cell self-organization for rapid and spontaneous formation of functional vessels

Most achievements to engineer blood vessels are based on multiple-step manipulations such as manual sheet rolling or sequential cell seeding followed by scaffold degradation. Here, we propose a one-step strategy using a microfluidic coextrusion device to produce mature functional blood vessels. A hollow alginate hydrogel tube is internally coated with extracellular matrix to direct the self-assembly of a mixture of endothelial cells (ECs) and smooth muscle cells (SMCs). The resulting vascular structure has the correct configuration of lumen, an inner lining of ECs, and outer sheath of SMCs. These "vesseloids" reach homeostasis within a day and exhibit the following properties expected for functional vessels (i) quiescence, (ii) perfusability, and (iii) contractility in response to vasoconstrictor agents. Together, these findings provide an original and simple strategy to generate functional artificial vessels and pave the way for further developments in vascular graft and tissue engineering and for deciphering the angiogenesis process.

Effects of ethanol and ethanol metabolites on intrinsic function of mesenteric resistance arteries

Evidence suggests that ethanol-induced hypertension is associated with increased cardiovascular responsiveness to vasopressors in vivo and enhanced reactivity of isolated arteries to vasopressors ex vivo. The underlying mechanisms are not well understood and the contribution of ethanol metabolites to vascular effects induced by ethanol consumption are unclear. Mesenteric resistance arteries were harvested from Sprague-Dawley rats. Pressure myography was utilized to test effects of ethanol, acetaldehyde and phosphatidylethanol on myogenic tone and on vasoconstriction induced by phenylephrine, arginine vasopressin (aVP), endothelin-1 and KCl. Ethanol, acetaldehyde and phosphatidylethanol concentrations were monitored during the experiments. Ethanol concentrations in the vessel bath decreased with a half-life of 25min; acetaldehyde and phosphatidylethanol concentrations remained constant. Pretreatment with ethanol dose-dependently increased the potency of phenylephrine to induce vasoconstriction 4-fold (p<0.01). These effects were comparable when arteries were pre-treated with a single dose of ethanol for 30min and when ethanol concentrations were kept constant during 30min and 60min of pretreatment. While ethanol also dose-dependently increased the potency of aVP to induce vasoconstriction 1.7-fold (p<0.05), it did not affect vasoconstriction induced by endothelin-1 or KCl. Acetaldehyde pre-treatment (30 min) dose-dependently increased the potency of phenylephrine to induce vasoconstriction 2.7-fold (p<0.01) but did not affect other vasoconstrictor responses. Phosphatidylethanol did not affect any vasoconstrictor responses. Ethanol and its metabolites did not affect myogenic tone. These data suggest that ethanol and acetaldehyde selectively sensitize intrinsic constrictor responses upon activation of vascular α₁-adrenergic and/or vasopressin receptors at clinically relevant concentrations. Our findings support the concept that enhanced vasoreactivity to vasoactive hormones contributes to the development of hypertension induced by ethanol consumption. Ex vivo exposure of resistance arteries to ethanol and acetaldehyde resembles effects of chronic ethanol consumption on intrinsic vascular function, and thus could serve as test platform to evaluate interventions aimed to mitigate vascular effects associated with ethanol consumption.

Vascular pathology of large cerebral arteries in experimental subarachnoid hemorrhage: Vasoconstriction, functional CGRP depletion and maintained CGRP sensitivity

Subarachnoid hemorrhage (SAH) is associated with increased cerebral artery sensitivity to vasoconstrictors and release of the perivascular sensory vasodilator CGRP. In the current study the constrictive phenotype and the vasodilatory effects of exogenous and endogenous perivascular CGRP were characterized in detail applying myograph technology to cerebral artery segments isolated from experimental SAH and sham-operated rats. Following experimental SAH, cerebral arteries exhibited increased vasoconstriction to endothelin-1, 5-hydroxytryptamine and U46419. In addition, depolarization-induced vasoconstriction (60 mM potassium) was significantly increased, supporting a general SAH-associated vasoconstrictive phenotype. Using exogenous CGRP, we demonstrated that sensitivity of the arteries to CGRP-induced vasodilation was unchanged after SAH. However, vasodilation in response to capsaicin (100 nM), a sensory nerve activator used to release perivascular CGRP, was significantly reduced by SAH (P = 0.0079). Because CGRP-mediated dilation is an important counterbalance to increased arterial contractility, a reduction in CGRP release after SAH would exacerbate the vasospasms that occur after SAH. A similar finding was obtained with artery culture (24 h), an in vitro model of SAH-induced vascular dysfunction. The arterial segments maintained sensitivity to exogenous CGRP but showed reduced capsaicin-induced vasodilation. To test whether a metabolically stable CGRP analogue could be used to supplement the loss of perivascular CGRP release in SAH, SAX was systemically administered in our in vivo SAH model. SAX treatment, however, induced CGRP-desensitization and did not prevent the development of vasoconstriction in cerebral arteries after SAH.

ETAR and protein kinase A pathway mediate ET-1 sensitization of TRPA1 channel: A molecular mechanism of ET-1-induced mechanical hyperalgesia

Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor that has been widely known as a pain mediator involved in various pain states. Evidence indicates that ET-1 sensitizes transient receptor potential cation channel, subfamily A, member 1 (TRPA1) in vivo. But the molecular mechanisms still remain unknown. We aim to explore whether ET-1 sensitizes TRPA1 in primary sensory neurons and the molecular mechanisms. Ca2+ imaging, immunostaining, electrophysiology, animal behavioral assay combined with pharmacological experiments were performed. ET-1 sensitized TRPA1-mediated Ca2+ responses in human embryonic kidney (HEK)293 cells as well as in cultured native mouse dorsal root ganglion (DRG) neurons. ET-1 also sensitized TRPA1 channel currents. ET-1 sensitized TRPA1 activated by endogenous agonist H2O2. ETA receptor (ETAR) colocalized with TRPA1 in DRG neurons. ET-1-induced TRPA1 sensitization in vivo was mediated via ETAR and protein kinase A (PKA) pathway in HEK293 cells and DRG neurons. Pharmacological blocking of ETAR, PKA, and TRPA1 significantly attenuated ET-1-induced mechanical hyperalgesia in mice. Our results suggest that TRPA1 acts as a molecular target for ET-1, and sensitization of TRPA1 through ETAR-PKA pathway contributes to ET-1-induced mechanical hyperalgesia. Pharmacological targeting of TRPA1 and ETAR-PKA pathway may provide effective strategies to alleviate pain conditions associated with ET-1.

Microarray analysis of long non-coding RNA and mRNA expression profiles in diabetic cardiomyopathy using human induced pluripotent stem cell-derived cardiomyocytes

AIM

This study aims to investigate the altered expression signature of long non-coding RNAs, mRNAs and deregulated pathways related to diabetic cardiomyopathy disease pathogenesis.

METHOD

We utilize the previously established in vitro diabetic cardiomyopathy model of human induced pluripotent stem cell-derived human cardiomyocytes to perform long non-coding RNA and mRNA expression analysis on glucose (11 mM), endothelin-1 (10 nM) and cortisol (1 µM) stimulated human induced pluripotent stem cell-derived human cardiomyocytes to interrogate diabetic cardiomyopathy associated RNA expression profile.

RESULT

Out of 20,730 mRNAs and 40,173 long non-coding RNAs being screened, 2046 long non-coding RNAs and 1582 mRNAs were differentially regulated (fold change > 2, p < 0.05) between diabetic cardiomyopathy and control group, of which more than half were intergenic and antisense long non-coding RNAs. Most of the coding transcripts were associated with processes like inflammation, structural reorganization, metabolism, smooth muscle contraction, focal adhesion and repair contributing towards the development of diabetic cardiomyopathy. The subgroup analysis further revealed 411 long non-coding RNAs being co-expressed with neighbouring genes. However, our coding-non-coding co-expression analysis showed an overall 48,155 co-expression network connections. In addition to that, the long non-coding RNAs with highest network connections were profoundly enriched for focal adhesion, cell-matrix adhesion and muscle contraction.

CONCLUSION

These results provide comprehensive data about the pathways and regulatory mechanisms associated with diabetic cardiomyopathy and indicate that long non-coding RNAs may play a crucial role in diabetic cardiomyopathy.

The effects of proton pump inhibitor on hepatic vascular responsiveness and hemodynamics in cirrhotic rats

BACKGROUND

Liver cirrhosis is associated with increased intrahepatic resistance due to hepatic fibrosis and exaggerated vasoconstriction. Recent studies have indicated that proton pump inhibitors (PPIs), in addition to acid suppression, modulate vasoactive substances and vasoresponsiveness. PPIs are frequently prescribed in patients with cirrhosis due to a higher prevalence of peptic ulcers, however other impacts are unknown.

METHODS

Liver cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (BDL). On the 29th day after BDL and after hemodynamic measurements, the intrahepatic vascular responsiveness to high concentrations of endothelin-1 (ET-1) was evaluated after preincubation with (1) Krebs solution (vehicle), (2) esomeprazole (30 μM), or (3) esomeprazole plus N^ω-nitro l-arginine (NNA, a non-selective NO synthase (NOS) inhibitor, 10^-4 M). After perfusion, the hepatic protein expressions of endothelial NOS (eNOS), inducible NOS (iNOS), cyclooxygenase (COX)-1, COX-2, endothelin-1, DDAH-1 (dimethylarginine dimethylaminohydrolase-1, ADMA inhibitor), DDAH-2, ADMA (asymmetrical dimethyl arginine, NOS inhibitor) were evaluated. In the chronic model, the BDL rats received (1) vehicle; or (2) esomeprazole (3.6 mg/kg/day, oral gavage) from the 1st to 28th day after BDL. On the 29th day and after hemodynamic measurements, plasma liver biochemistry and liver fibrosis were evaluated.

RESULTS

Esomeprazole did not affect hepatic ET-1 vasoresponsiveness. The hepatic protein expressions of the aforementioned factors were not significantly different among the groups. There were no significant differences in hemodynamics, liver biochemistry and hepatic fibrosis after chronic esomeprazole administration.

CONCLUSION

PPIs did not affect hepatic vasoresponsiveness or the release of vasoactive substances. Furthermore, they did not influence hemodynamics, liver biochemistry or severity of hepatic fibrosis in the cirrhotic rats.

Effects Of Endothelin-1 On Intracellular Tetrahydrobiopterin Levels In Vascular Tissue

OBJECTIVE

Tetrahydrobiopterin (BH4) is the essential cofactor of endothelial nitric oxide synthase (eNOS) and intracellular levels of BH4 is regulated by oxidative stress. The aim of this paper was to describe the influence of exogenous endothelin-1 on intracellular BH4 and its oxidation products dihydrobiopterin (BH2) and biopterin (B) in a wide range of vascular tissue.

DESIGN

Segments of internal mammary artery (IMA) and human saphenous vein (SV) from 41 patients undergoing elective surgery were incubated in ET-1 (0.1 μM). Aorta and lung from transgenic mice overexpressing ET-1 in the endothelium (ET-TG) were analysed with regards to intracellular biopterin levels. Human umbilical vein endothelial cells (HUVEC) were incubated in ET-1 (0.1 μM) and intracellular biopterin levels were analysed. From 6 healthy women undergoing caesarean section, subcutaneous fat was harvested and the resistance arteries in these biopsies were tested for ET-mediated endothelial dysfunction.

RESULTS

In HUVEC, exogenous ET-1 (0.1 μM) did not significantly change intracellular BH4, 1.54 ± 1.7 vs 1.68 ± 1.8 pmol/mg protein; p = .8. In IMA and SV, exogenous ET-1(0.1 μM) did not change intracellular BH4 n = 10, p = .4. In aorta from wild type vs ET-TG mice there was no significant difference in intracellular BH4 between the groups: 1.3 ± 0.49 vs 1.23 ± 0.3 pmol/mg protein; p = .6. In resistance arteries (n = 6) BH4 together with DTE (an antioxidant) was not able to prevent ET-mediated endothelial dysfunction.

CONCLUSION

ET-1 did not significantly alter intracellular tetrahydrobiopterin levels in IMA, SV, HUVEC or aorta from ET-TG mice. These findings are important for future research in ET-1 mediated superoxide production and endothelial dysfunction.

Enhanced Renal Afferent Arteriolar Reactive Oxygen Species and Contractility to Endothelin-1 Are Associated with Canonical Wnt Signaling in Diabetic Mice

BACKGROUND/AIMS

Canonical Wnt signaling is involved in oxidative stress, vasculopathy and diabetes mellitus but its role in diabetic renal microvascular dysfunction is unclear. We tested the hypothesis that enhanced canonical Wnt signaling in renal afferent arterioles from diabetic mice increases reactive oxygen species (ROS) and contractions to endothelin-1 (ET-1).

METHODS

Streptozotocin-induced diabetes or control C57Bl/6 mice received vehicle or sulindac (40 mg·kg-1·day-1) to block Wnt signaling for 4 weeks. ET-1 contractions were measured by changes of afferent arteriolar diameter. Arteriolar H2O2, O2 -, protein expression and enzymatic activity were assessed using sensitive fluorescence probes, immunoblotting and colorimetric assay separately.

RESULTS

Compared to control, diabetic mouse afferent arteriole had increased O2- (+ 84%) and H2O2 (+ 91%) and enhanced responses to ET-1 at 10-8 mol·l-1 (-72±4% of versus -43±4%, P< 0.05) accompanied by reduced protein expressions and activities for catalase and superoxide dismutase 2 (SOD2). Arteriolar O2 - was increased further by ET-1 and contractions to ET-1 reduced by PEG-SOD in both groups whereas H2O2 unchanged by ET-1 and contractions were reduced by PEG-catalase selectively in diabetic mice. The Wnt signaling protein β-catenin was upregulated (3.3-fold decrease in p-β-catenin/β-catenin) while the glycogen synthase kinase-3β (GSK-3β) was downregulated (2.6-fold increase in p-GSK-3β/ GSK-3β) in preglomerular vessels of diabetic mice. Sulindac normalized the Wnt signaling proteins, arteriolar O2 -, H2O2 and ET-1 contractions while doubling microvascular catalase and SOD2 expression in diabetic mice.

CONCLUSION

Increased ROS, notably H2O2 contributes to enhanced afferent arteriolar responses to ET-1 in diabetes, which is closely associated with Wnt signaling. Antioxidant pharmacological strategies targeting Wnt signaling may improve vascular function in diabetic nephropathy.

The role of Rho-kinase and calcium ions in constriction triggered by ET-1

Endothelin-1 (ET-1) is one of the key factors regulating tension of smooth muscles in blood vessels. It is believed that ET-1 plays an important role in pathogenesis of hypertension, and cardiovascular diseases; therefore, research in order to limit ET-1-mediated action is still in progress. The main objective of this paper was to evaluate the role of Rho-kinase in the ET-1-induced constriction of arteries. The analysis also included significance of intra- and extracellular pool of calcium ions in constriction triggered by ET-1. The studies were performed on perfused Wistar rat tail arteries. Concentration response curve (CRC) was determined for ET-1 in the presence of increased concentrations of Rho-kinase inhibitor (Y-27632) and IP3-receptor antagonist (2APB), both in reference to constriction triggered by solely ET-1. Afterwards, the influence of calcium ions present in the perfusion fluid was evaluated in terms of the effect triggered by 2APB and occurring in arteries constricted by ET-1. ET-1, in concentration dependent manner, leads to increase in perfusion pressure. Y-27632 and 2APB lead to shift of the concentration response curve for ET-1 to the right with simultaneously lowered maximum effect. There was no difference in reaction of the artery constricted by ET-1 and treated with 2APB in solution containing calcium and in calcium-free solution. Vasoconstrictive action of endothelin is not significantly dependent on the inflow of extracellular calcium, but it is proportional to inflow of Ca²⁺ related to activation of IP3 receptors and to Rho-kinase activity.

Vasorelaxant effect of quercetin on cerebral basilar artery in vitro and the underlying mechanisms study

The aim of this study is to investigate the vasorelaxant effect of quercetin on cerebral basilar artery in vitro and provide a preliminary discussion concerning the underlying mechanisms. Using a DMT-isolated micro vessel system, quercetin was found to exhibit a vasodilatory effect on basilar arteries contracted by potassium chloride (KCl), endothelin-1 (ET-1), and 5-hydroxytryptamine (5-HT). The vasorelaxant effect of quercetin was partially attenuated when endothelium cells were removed. L-NAME, indomethacin, and ODQ treatment also decreased the potency of quercetin. In endothelium-denuded rings, the vasorelaxant effect of quercetin was not influenced by K⁺ channel inhibitors. However, quercetin inhibited KCl induced extracellular calcium influx and ET-1 induced transient intracellular calcium release in a Ca²⁺-free solution. In conclusion, quercetin induced relaxation of the basilar artery in vitro is partially dependent on endothelium, which is mainly related to NO and COX pathways. It also induces relaxation through blockage of calcium channels.

Unraveling endothelin-1 induced hypercontractility of human pulmonary artery smooth muscle cells from patients with pulmonary arterial hypertension

Contraction of human pulmonary artery smooth muscle cells (HPASMC) isolated from pulmonary arterial hypertensive (PAH) and normal (non-PAH) subject lungs was determined and measured with real-time electrical impedance. Treatment of HPASMC with vasoactive peptides, endothelin-1 (ET-1) and bradykinin (BK) but not angiotensin II, induced a temporal decrease in the electrical impedance profile mirroring constrictive morphological change of the cells which typically was more robust in PAH as opposed to non-PAH cells. Inhibition with LIMKi3 and a cofilin targeted motif mimicking cell permeable peptide (MMCPP) had no effect on ET-1 induced HPASMC contraction indicating a negligible role for these actin regulatory proteins. On the other hand, a MMCPP blocking the activity of caldesmon reduced ET-1 promoted contraction pointing to a regulatory role of this protein and its activation pathway in HPASMC contraction. Inhibition of this MEK/ERK/p90RSK pathway, which is an upstream regulator of caldesmon phosphorylation, reduced ET-1 induced cell contraction. While the regulation of ET-1 induced cell contraction was found to be similar in PAH and non-PAH cells, a key difference was the response to pharmacological inhibitors and to siRNA knockdown of Rho kinases (ROCK1/ROCK2). The PAH cells required much higher concentrations of inhibitors to abrogate ET-1 induced contractions and their contraction was not affected by siRNA against either ROCK1 or ROCK2. Lastly, blocking of L-type and T-type Ca2+ channels had no effect on ET-1 or BK induced contraction. However, inhibiting the activity of the sarcoplasmic reticulum Ca2+ ATPase blunted ET-1 and BK induced HPASMC contraction in both PAH and non-PAH derived HPASMC. In summary, our findings here together with previous communications illustrate similarities and differences in the regulation PAH and non-PAH smooth muscle cell contraction relating to calcium translocation, RhoA/ROCK signaling and the activity of caldesmon. These findings may provide useful tools in achieving the regulation of the vascular hypercontractility taking place in PAH.

NMDA-Type Glutamate Receptor Activation Promotes Vascular Remodeling and Pulmonary Arterial Hypertension

BACKGROUND

Excessive proliferation and apoptosis resistance in pulmonary vascular cells underlie vascular remodeling in pulmonary arterial hypertension (PAH). Specific treatments for PAH exist, mostly targeting endothelial dysfunction, but high pulmonary arterial pressure still causes heart failure and death. Pulmonary vascular remodeling may be driven by metabolic reprogramming of vascular cells to increase glutaminolysis and glutamate production. The N-methyl-d-aspartate receptor (NMDAR), a major neuronal glutamate receptor, is also expressed on vascular cells, but its role in PAH is unknown.

METHODS

We assessed the status of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and controls through mass spectrometry imaging, Western blotting, and immunohistochemistry. We measured the glutamate release from cultured pulmonary vascular cells using enzymatic assays and analyzed NMDAR regulation/phosphorylation through Western blot experiments. The effect of NMDAR blockade on human pulmonary arterial smooth muscle cell proliferation was determined using a BrdU incorporation assay. We assessed the role of NMDARs in vascular remodeling associated to pulmonary hypertension, in both smooth muscle-specific NMDAR knockout mice exposed to chronic hypoxia and the monocrotaline rat model of pulmonary hypertension using NMDAR blockers.

RESULTS

We report glutamate accumulation, upregulation of the NMDAR, and NMDAR engagement reflected by increases in GluN1-subunit phosphorylation in the pulmonary arteries of human patients with PAH. K_v channel inhibition and type A-selective endothelin receptor activation amplified calcium-dependent glutamate release from human pulmonary arterial smooth muscle cell, and type A-selective endothelin receptor and platelet-derived growth factor receptor activation led to NMDAR engagement, highlighting crosstalk between the glutamate-NMDAR axis and major PAH-associated pathways. The platelet-derived growth factor-BB-induced proliferation of human pulmonary arterial smooth muscle cells involved NMDAR activation and phosphorylated GluN1 subunit localization to cell-cell contacts, consistent with glutamatergic communication between proliferating human pulmonary arterial smooth muscle cells via NMDARs. Smooth-muscle NMDAR deficiency in mice attenuated the vascular remodeling triggered by chronic hypoxia, highlighting the role of vascular NMDARs in pulmonary hypertension. Pharmacological NMDAR blockade in the monocrotaline rat model of pulmonary hypertension had beneficial effects on cardiac and vascular remodeling, decreasing endothelial dysfunction, cell proliferation, and apoptosis resistance while disrupting the glutamate-NMDAR pathway in pulmonary arteries.

CONCLUSIONS

These results reveal a dysregulation of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and identify vascular NMDARs as targets for antiremodeling treatments in PAH.

Sustained Activation of Rho GTPases Promotes a Synthetic Pulmonary Artery Smooth Muscle Cell Phenotype in Neprilysin Null Mice

OBJECTIVE

Pulmonary artery smooth muscle cells (PASMCs) from neprilysin (NEP) null mice exhibit a synthetic phenotype and increased activation of Rho GTPases compared with their wild-type counterparts. Although Rho GTPases are known to promote a contractile SMC phenotype, we hypothesize that their sustained activity decreases SM-protein expression in these cells.

APPROACH AND RESULTS

PASMCs isolated from wild-type and NEP-/- mice were used to assess levels of SM-proteins (SM-actin, SM-myosin, SM22, and calponin) by Western blotting, and were lower in NEP-/- PASMCs compared with wild-type. Rac and Rho (ras homology family member) levels and activity were higher in NEP-/- PASMCs, and ShRNA to Rac and Rho restored SM-protein, and attenuated the enhanced migration and proliferation of NEP-/- PASMCs. SM-gene repressors, p-Elk-1, and Klf4 (Kruppel lung factor 4), were higher in NEP-/- PASMCs and decreased by shRNA to Rac and Rho. Costimulation of wild-type PASMCs with PDGF (platelet-derived growth factor) and the NEP substrate, ET-1 (endothelin-1), increased Rac and Rho activity, and decreased SM-protein levels mimicking the NEP knock-out phenotype. Activation of Rac and Rho and downstream effectors was observed in lung tissue from NEP-/- mice and humans with chronic obstructive pulmonary disease.

CONCLUSIONS

Sustained Rho activation in NEP-/- PASMCs is associated with a decrease in SM-protein levels and increased migration and proliferation. Inactivation of RhoGDI (Rho guanine dissociation inhibitor) and RhoGAP (Rho GTPase activating protein) by phosphorylation may contribute to prolonged activation of Rho in NEP-/- PASMCs. Rho GTPases may thus have a role in integration of signals between vasopeptides and growth factor receptors and could influence pathways that suppress SM-proteins to promote a synthetic phenotype.

[Comparison of the synchronous changes of vascular tension and intracellular Ca2+ signal in third-order branches of mesenteric arteries under the different objective amplification of confocal microscope]

This study was aimed to establish an optimized method to observe the synchronous changes of vascular tension and intracellular Ca²⁺ signal in the third-order branches of mesenteric arteries (sMA, diameter: 100-300 μm). The vascular tension and intracellular Ca²⁺ signal changes in response to potassium chloride (KCl), endothelin-1 (ET-1) and Gd³⁺ were detected using confocal wire myograph system and confocal laser scanning microscopy imaging technique, respectively. The experimental results were analyzed to explore the optimal experimental conditions. The results showed that KCl caused contraction in sMA significantly, and the intracellular Ca²⁺ level of vascular smooth muscle cells (VSMCs) was also increased under 20× and 40× objective lens. Compared with those under the 40× objective lens, the Ca²⁺ signal change was larger and the fluorescence value was more stable under the 20× objective lens, whereas the Ca²⁺ signal change was not obvious under the 10× objective lens. ET-1 (1-10 nmol/L) caused concentration dependent contraction in sMA significantly, and the intracellular Ca²⁺ signal of VSMCs was also enhanced in a concentration dependent manner. Additionally, Gd³⁺ significantly reduced the contraction of sMA and the intracellular Ca²⁺ signal of VSMCs caused by ET-1. The results suggest that the intracellular Ca²⁺ signal of VSMCs changes with vascular contraction or relaxation caused by the agonists or antagonists of Ca²⁺ channels. We successfully recorded both changes synchronously using confocal wire myograph system and confocal laser scanning microscopy imaging technique at the same time. Based on the analysis of the experimental results, we concluded that 20× objective lens provides the best experimental condition. Compared to combination of vascular tone detection method and real-time cellular fluorescence imaging technique, the present synchronous method is convenient and helpful to reduce experimental error.

Alterations in endothelin type B receptor contribute to microvascular dysfunction in women who have had preeclampsia

Microvascular dysfunction originating during a preeclamptic pregnancy persists postpartum and probably contributes to increased CVD risk in these women. One putative mechanism contributing to this dysfunction is increased vasoconstrictor sensitivity to endothelin-1 (ET-1), mediated by alterations in ET-1 receptor type-B (ETBR). We evaluated ET-1 sensitivity, ETAR, and ETBR contributions to ET-1-mediated constriction, and the mechanistic role of ETBR in endothelium-dependent dilation in vivo in the microvasculature of postpartum women who had preeclampsia (PrEC, n=12) and control women who had a healthy pregnancy (HC, n=12). We hypothesized that (1) PrEC would have a greater vasoconstrictor response to ET-1, and (2) reduced ETBR-mediated dilation. We further hypothesized that ETBR-blockade would attenuate endothelium-dependent vasodilation in HC, but not PrEC. Microvascular reactivity was assessed by measurement of cutaneous vascular conductance responses to graded infusion of ET-1 (10-20-10-8 mol/l), ET-1 + 500 nmol/l BQ-123 (ETAR-blockade), and ET-1 + 300 nmol/l BQ-788 (ETBR-blockade), and during graded infusion of acetylcholine (ACh, 10-7-102 mmol/l) and a standardized local heating protocol with and without ETBR-inhibition. PrEC had an increased vasoconstriction response to ET-1 (P=0.02). PrEC demonstrated reduced dilation responses to selective ETBR stimulation with ET-1 (P=0.01). ETBR-inhibition augmented ET-1-mediated constriction in HC (P=0.01) but attenuated ET-1-mediated constriction in PrEC (P=0.003). ETBR-inhibition attenuated endothelium-dependent vasodilation responses to 100mmol/l ACh (P=0.04) and local heat (P=0.003) in HC but increased vasodilation (ACh: P=0.01; local heat: P=0.03) in PrEC. Women who have had preeclampsia demonstrate augmented vasoconstrictor sensitivity to ET-1, mediated by altered ETBR signaling. Furthermore, altered ETBR function contributes to diminished endothelium-dependent dilation in previously preeclamptic women.

An impedance-based cell contraction assay using human primary smooth muscle cells and fibroblasts

INTRODUCTION

Many cell types (including muscle cells and fibroblasts) can contract at physiological conditions and their contractility may change during tissue injury and repair or other diseases such as allergy and asthma. The conventional gel contraction assay is commonly used to monitor the cellular contractility. It is a manual assay and the experiment usually takes hours even days to complete. As its readout is not always accurate and reliable, the gel contraction assay is often used to qualitatively (but not quantitatively) characterize cellular contractility under various conditions.

METHOD

To overcome the limits of the gel contraction assay, we developed an impedance-based contraction assay using the xCELLigence RTCA MP system. This technology utilizes special 96-well E-plates with gold microelectrode arrays printed in individual wells to monitor cellular adhesion by recording the electrical impedance in real time. The impedance change (percentage vs. control) can be used as the readout for cellular contraction.

RESULTS

We demonstrated that the impedance-based contraction assay can be performed within 2h. Using this new method, we quantitatively characterized the effects of several contractile stimulators and inhibitors on human primary bronchial smooth muscle cells and primary lung fibroblasts.

DISCUSSION

The impedance-based contraction assay can be applied to both basic research and drug discovery for characterizing cellular contraction quantitatively. Because it has high throughput capacity and high reproducibility, the impedance-based contraction assay is useful for high throughput functional screening in drug industry.

Functional local crosstalk of inositol 1,4,5-trisphosphate receptor- and ryanodine receptor-dependent Ca2+ release in atrial cardiomyocytes

Aims

Enhanced inositol 1,4,5-trisphosphate receptor (InsP3R2) expression has been associated with a variety of proarrhythmogenic cardiac disorders. The functional interaction between the two major Ca2+ release mechanisms in cardiomyocytes, Ca2+ release mediated by ryanodine receptors (RyR2s) and InsP3-induced intracellular Ca2+ release (IP3ICR) remains enigmatic. We aimed at identifying characterizing local IP3ICR events, and elucidating functional local crosstalk mechanisms between cardiac InsP3R2s and RyR2s under conditions of enhanced cardiac specific InsP3R2 activity.

Methods and results

Using confocal imaging and two-dimensional spark analysis, we demonstrate in atrial myocytes (mouse model cardiac specific overexpressing InsP3R2s) that local Ca2+ release through InsP3Rs (Ca2+ puff) directly activates RyRs and triggers elementary Ca2+ release events (Ca2+ sparks). In the presence of increased intracellular InsP3 concentrations IP3ICR can modulate RyRs openings and Ca2+ spark probability. We show as well that IP3ICR remains under local control of Ca2+ release through RyRs.

Conclusions

Our results support the concept of bidirectional interaction between RyRs and InsP3Rs (i.e. Ca2+ sparks and Ca2+ puffs) in atrial myocytes. We conclude that highly efficient InsP3 dependent SR-Ca2+ flux constitute the main mechanism of functional crosstalk between InsP3Rs and RyRs resulting in more Ca2+ sensitized RyRs to trigger subsequent Ca2+-induced Ca2+ release activation. In this way, bidirectional local interaction of both SR-Ca2+ release channels may contribute to the shaping of global Ca2+ transients and thereby to contractility in cardiac myocytes.

The S1P1 receptor-selective agonist CYM-5442 protects retinal ganglion cells in endothelin-1 induced retinal ganglion cell loss

We investigated the feasibility and efficacy of using a specific sphingosine 1-phosphate (S1P1) receptor agonist, CYM-5442, to slow or block retinal ganglion cell (RGC) loss in endothelin-1 (ET-1) induced RGC loss. A single intravitreal injection of ET-1 (20pmol/ul), a potent vasoactive peptide that produces retinal vessels vasoconstriction, was used to induce and characterize RGC-specific cell death. CYM-5442 (1 mgr/kg) or vehicle was administered intraperitoneally for five consecutive days after ET-1-induced RGC loss. The functional extent of RGC loss injury was evaluated with pattern visual evoked potentials (VEP) and electroretinography. RGCs and retinal nerve fiber layer (RNFL) thickness were assessed in vivo using optical coherence tomography and ex vivo using Brn3a immunohistochemistry in flat-mounted retinas. ET-1 caused significant RGC loss and function loss one week after intravitreal injection. VEP showed preserved visual function after CYM-5442 administration compared to vehicle-treated animals (11.95 ± 0.86 μV vs 3.47 ± 1.20 μV, n = 12) (p < 0.05). RNFL was significantly thicker in the CYM treated-animals compared to the vehicle (93.62 ± 3.22 μm vs 77.72 ± 0.35 μm, n = 12) (p < 0.05). Furthermore, Brn3a immunohistochemistry validated this observation, showing significantly higher RGCs numbers in CYM treated rats than in the vehicle group (76,540 ± 303 vs 52,426 ± 1,932 cells/retina, n = 9) (p = 0.05). CYM-5442 administration was associated with significant retinal cleaved caspase-3 deactivation, indicating reduced apoptotic levels. The results of the present study further demonstrate the important role of S1P1 receptor agonists to lessen intravitreal ET-1 induced RGC loss.

The effects of endothelin-1 on satellite glial cells in peripheral ganglia

Endothelins (ET) are a family of highly active neuropeptides with manifold influences via ET receptors (ETR) in both the peripheral and central nervous systems. We have shown previously that satellite glial cells (SGCs) in mouse trigeminal ganglia (TG) are extremely sensitive to ET-1 in evoking [Ca²⁺]_in increase, apparently via ET_BR activation, but there is no functional information on ETR in SGCs of other peripheral ganglia. Here we tested the effects of ET-1 on SGCs in nodose ganglia (NG), which is sensory, and superior cervical ganglia (Sup-CG), which is part of the sympathetic nervous system, and further investigated the influence of ET-1 on SGCs in TG. Using calcium imaging we found that SGCs in intact, freshly isolated NG and Sup-CG are highly sensitive to ET-1, with threshold concentration at 0.1nM. Our results showed that [Ca²⁺]_in elevation in response to ET-1 was partially due to Ca²⁺ influx from the extracellular space and partially to Ca²⁺ release from intracellular stores. Using receptor selective ETR agonists and antagonists, we found that the responses were mediated by mixed ET_AR/ET_BR in SGCs of NG and predominantly by ET_BR in SGCs of Sup-CG. By employing intracellular dye injection we examined coupling among SGCs around different neurons in the presence of 5nM ET-1 and observed coupling inhibition in all the three ganglion types. In summary, our work showed that SGCs in mouse sensory and sympathetic ganglia are highly sensitive to ET-1 and that this peptide markedly reduces SGCs coupling. We conclude that ET-1, which may participate in neuron-glia communications, has similar functions in wide range of peripheral ganglia.

MicroRNA-27a/b mediates endothelin-1-induced PPARγ reduction and proliferation of pulmonary artery smooth muscle cells

The down-regulation of peroxisome proliferator-activated receptor γ (PPARγ) expression has been found to correlate with the proliferation of pulmonary artery smooth muscle cells (PASMC), pulmonary vascular remodeling and pulmonary hypertension, while the molecular mechanisms underlying PPARγ reduction in PASMC remain largely unclear. The aim of the current study is to address this issue. Endothelin-1 (ET-1) dose- and time-dependently resulted in PPARγ reduction and proliferation of primary cultured rat PASMC, which was accompanied by the activation of nuclear factor-kappaB (NF-κB) and subsequent induction of microRNA-27a/b (miR-27a/b) expression. Chromatin immunoprecipitation assay revealed that NF-κB directly bound to the promoter regions of miR-27a/b. Luciferase reporter assay identified that miR-27a/b directly regulates the expression of PPARγ in PASMC. Further study indicated that the presence of either NF-κB inhibitor pyrrolidinedithiocarbamate or prior silencing miR-27a/b with anti-miRNA oligonucleotides suppressed ET-1-induced PPARγ reduction and proliferation of PASMC, while overexpression of miR-27a/b reduced PPARγ expression and enhanced PASMC proliferation. Taken together, our study demonstrates that ET-1 stimulates miR-27a/b expression by activation of the NF-κB pathway, which in turn results in PPARγ reduction and contributes to ET-1-induced PASMC proliferation.

Dual endothelin receptor antagonists contrast the effects induced by endothelin-1 on cultured human microvascular endothelial cells

OBJECTIVES

To evaluate the ability of dual endothelin (ET) receptor antagonists (ETA/ETB -ETA/BRAs) to contrast the ET-1-induced effects on cultured human microvascular endothelial cells (HMVECs).

METHODS

Some cultured HMVECs were untreated, or treated with ET-1 (100nM) or transforming growth factor β1 (TGFβ1, 10ng/mL) alone for 6 days, in order to induce the endothelial-to-mesenchymal transition (EndoMT). Other cultured HMVECs were pre-treated for 1hr with ETA/BRAs bosentan (10μM) or macitentan (1μM, 10μM) before the stimulation with ET-1 for 6 days. At the end of treatments, a mechanical injury was induced to cultured HMVECs (by scratching the cell monolayer with a sterile tip), and then the cell ability to re-fill the damaged area was determined after 24hrs. EndoMT phenotype markers and monocyte chemoattractant protein-1 (MCP-1) were evaluated by qRT-PCR and Western blotting. Statistical analysis was performed using Mann-Whitney-U non-parametric test.

RESULTS

Both ET-1 and TGFβ1 induced EndoMT and the MCP-1 over-expression in cultured HMVECs, as well as reduced the process of endothelial cell damage repair. Pre-treatment with ETA/BRAs let cultured HMVECs to significantly restore the in vitro damage of the cell monolayer and antagonised the EndoMT process as well as the MCP-1 over-expression (range p<0.05 - p<0.001). Conversely, untreated or TGFβ1-treated HMVECs were found unaffected by the ETA/BRAs treatments.

CONCLUSIONS

The treatment with dual ETA/BRAs seems to partially restore the altered cell function induced by ET-1 in cultured endothelial cells, and might justify their therapeutic efficiency in clinical conditions characterised by increased concentrations of ET-1.