Endothelial Nitric Oxide Release Research Articles

Antithrombotic and Antimicrobial Potential of S-Nitroso-1-Adamantanethiol-Impregnated Extracorporeal Circuit.

This study presents the utilization of a novel, highly lipophilic nitric oxide (NO) donor molecule, S-nitroso-1-adamantanethiol (SNAT), for developing an NO-emitting polymer surface aimed at preventing thrombus formation and bacterial infection in extracorporeal circuits (ECCs). S-nitroso-1-adamantanethiol, a tertiary nitrosothiol-bearing adamantane species, was synthesized, characterized, and used to impregnate polyvinyl chloride (PVC) tubing for subsequent in vivo evaluation. The impregnation process with SNAT preserved the original mechanical strength of the PVC. In vitro assessments revealed sustained NO release from the SNAT-impregnated PVC tubing (iSNAT), surpassing or matching endothelial NO release levels for up to 42 days. The initial NO release remained stable even after 1 year of storage at -20°C. The compatibility of iSNAT with various sterilization techniques (OPA Plus, hydrogen peroxide, EtO) was tested. Acute in vivo experiments in a rabbit model demonstrated significantly reduced thrombus formation in iSNAT ECCs compared with controls, indicating the feasibility of iSNAT to mitigate coagulation system activation and potentially eliminate the need for systemic anticoagulation. Moreover, iSNAT showed substantial inhibition of microbial biofilm formation, highlighting its dual functionality. These findings underscore the promising utility of iSNAT for long-term ECC applications, offering a multifaceted approach to enhancing biocompatibility and minimizing complications.

Lipid Emulsions Inhibit Labetalol-Induced Vasodilation in the Isolated Rat Aorta.

Lipid emulsions are used as adjuvant drugs to alleviate intractable cardiovascular collapse induced by drug toxicity. We aimed to examine the effect of lipid emulsions on labetalol-induced vasodilation and the underlying mechanism in the isolated rat aorta. We studied the effects of endothelial denudation, NW-nitro-l-arginine methyl ester (l-NAME), calmidazolium, methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a] quinoxalin-1-one (ODQ), and lipid emulsions on labetalol-induced vasodilation. We also evaluated the effects of lipid emulsions on cyclic guanosine monophosphate (cGMP) formation, endothelial nitric oxide synthase (eNOS) phosphorylation, and endothelial calcium levels induced by labetalol. Labetalol-induced vasodilation was higher in endothelium-intact aortas than that in endothelium-denuded aortas. l-NAME, calmidazolium, methylene blue, and ODQ inhibited labetalol-induced vasodilation in endothelium-intact aortas. Lipid emulsions inhibited labetalol-induced vasodilation in endothelium-intact and endothelium-denuded aortas. l-NAME, ODQ, and lipid emulsions inhibited labetalol-induced cGMP formation in endothelium-intact aortas. Lipid emulsions reversed the stimulatory and inhibitory eNOS (Ser1177 and Thr495) phosphorylation induced by labetalol in human umbilical vein endothelial cells and inhibited the labetalol-induced endothelial calcium increase. Moreover, it decreased labetalol concentration. These results suggest that lipid emulsions inhibit vasodilation induced by toxic doses of labetalol, which is mediated by the inhibition of endothelial nitric oxide release and reduction of labetalol concentration.

Exploring the effects of vasoactive constituents in large cardamom: implications for the anti-hypertensive effect via eNOS coupling pathway – an in-vitro study in rat endothelial cells

Endothelial dysfunction, linked to reduced eNOS expression and nitric oxide (NO) availability, contributes to cardiovascular diseases (CVDs). Large cardamom exhibits antihypertensive effects by augmenting NO levels and antioxidant activity. To decipher its mechanisms, selected constituents were docked with eNOS-associated target genes such as GTP cyclohydrolase I (GTPCH-1) and (dihydrofolate reductase [DHFR]). Endothelial damage induced by L-NAME and fructose was countered by assessing nitric oxide metabolites (NOx), tetrahydrobipterin (BH4 levels), GCH-I expression and super oxide dismutase (SOD) activity after constituent incubation. Cyanidin-3-O-glucoside and petunidin-3-O-glucoside notably restored impaired vascular markers in both models. These phytoconstituents are likely to activate GCH-BH4-eNOS pathways, upregulating SOD and NO expression, maintaining endothelial integrity. Large cardamom’s antihypertensive effects may stem from these components, synergistically enhancing endothelial NO release via the eNOS pathway.

Losartan and metabolite EXP3179 activate endothelial function without lowering blood pressure in AT2 receptor KO mice

BackgroundWe have documented profound release of nitric oxide (NO) and endothelium-derived hyperpolarization factor (EDHF) by angiotensin II (ANGII) receptor 1 (AT1) blocker (ARB) losartan and its unique metabolite EXP3179, a pleiotropic effect that may help rationalize the protective properties of ARBs. Since blood pressure (BP) lowering by ARBs likely require an ANGII-dependent switch from AT1 to ANGII receptor 2 (AT2) signaling, a receptor known to stimulate endothelial NO release, we investigated the contribution of AT1 and AT2 to losartan and EXP3179’s endothelial function-activating properties. Experimental ApproachTwo AT1 ligands were used in an attempt to block the AT1-dependent endothelium-enhancing effects of EXP3179. AT2-null mice were used to evaluate the acute ex vivo and chronic in vivo effects of EXP3179 (20μM) and losartan (0.6 g/l), respectively, on endothelial function, BP and aortic stiffness. Key resultsEx vivo blockade of AT1 receptors did not attenuate EXP3179’s effects on NO and EDHF-dependent endothelial function activation. We observed significant reductions in PE-induced contractility with EXP3179 in both WT and AT2 knockout (KO) aortic rings. In vivo, a 1-month chronic treatment with losartan did not affect pulse wave velocity (PWV) but decreased PE-induced contraction by 74.9 % in WT (p < 0.0001) and 47.3 % in AT2 KO (p < 0.05). Presence of AT2 was critical to losartan’s BP lowering activity. ConclusionIn contrast to BP lowering, the endothelial function-enhancing effects of losartan and EXP3179 are mostly independent of the classic ANGII/AT1/AT2 pathway, which sheds light on ARB pleiotropism.

Topically Applied N,N-Dimethylglycine Sodium Salt Enhances Human Skin Blood Flow by Inducing Endothelial Nitric Oxide Release

Topically Applied N,N-Dimethylglycine Sodium Salt Enhances Human Skin Blood Flow by Inducing Endothelial Nitric Oxide Release

Indole-3-Propionic Acid, a Gut Microbiota-Derived Tryptophan Metabolite, Promotes Endothelial Dysfunction Impairing Purinergic-Induced Nitric Oxide Release in Endothelial Cells.

Different gut microbiota-derived metabolites influence cardiovascular function, and, among all, the role of indole-3-propionic acid (IPA), from tryptophan metabolism, shows controversial effects. The aim of this study was to evaluate its role in endothelial dysfunction. IPA effects were studied on bovine aortic endothelial cells (BAE-1). First, IPA cytotoxicity was evaluated by an MTS assay. Then, the levels of intracellular reactive oxygen species (ROS) were evaluated by a microplate reader or fluorescence microscopy with the CellROX® Green probe, and nitric oxide (NO) production was studied by fluorescence microscopy with the DAR4M-AM probe after acute or chronic treatment. Finally, immunoblotting analysis for endothelial nitric oxide synthase (eNOS) phosphorylation (p-eNOS) was performed. In BAE-1, IPA was not cytotoxic, except for the highest concentration (5 mM) after 48 h of treatment, and it showed neither oxidant nor antioxidant activity. However, the physiological concentration of IPA (1 μM) significantly reduced NO released by adenosine triphosphate (ATP)-stimulated BAE-1. These last data were confirmed by Western blot analysis, where IPA induced a significant reduction in p-eNOS in purinergic-stimulated BAE-1. Given these data, we can speculate that IPA negatively affects the physiological control of vascular tone by impairing the endothelial NO release induced by purinergic stimulation. These results represent a starting point for understanding the mechanisms underlying the relationship between gut microbiota metabolites and cardiometabolic health.

Novel bioactive lipids enhanced HDL-mediated cholesterol efflux from macrophages through the ABCA1 receptor pathway

High-density lipoprotein (HDL) has traditionally been acknowledged as "good cholesterol" owing to its significant association with a decreased risk of atherosclerosis. This association is primarily attributed to HDL's direct involvement in cholesterol efflux capacity, which plays a pivotal role in reverse cholesterol transport. A novel active compound from Nannochloropsis microalgae termed lyso-DGTS, a lipid that contains EPA fatty acids, was previously isolated and found to increase paraoxonase 1 activity and enhance HDL-mediated cholesterol efflux and HDL-induced endothelial nitric oxide release. Here, the effect of different lyso-DGTS derivatives and analogs on HDL-mediated cholesterol efflux from macrophages was examined, and the mechanism was explored. Structure–activity relationships were established to characterize the essential lipid moieties responsible for HDL-mediated cholesterol efflux from macrophages. Lyso-DGTS, 1-carboxy-N-N-N-trimethyl-3-oleamidopropan-1-aminium, and lyso-platelet-activating factor increased HDL-mediated cholesterol efflux from macrophages dose-dependently, mainly via the ABCA1-mediated cholesterol efflux pathway. The effect of lyso-DGTS derivatives and analogs on the surface polarity of HDL was examined using the Laurdan generalized polarization (GP) assay. A reverse Pearson linear regression was obtained between Laurdan GP values and HDL-mediated cholesterol efflux. Because the incorporation of bioactive lipids into the surface phospholipid layer of HDL leads to a decrease in Laurdan GP, these bioactive lipids may induce lower phospholipid ordering and greater free space on the HDL particle surface, thereby enhancing apolipoprotein A1 binding to the ABCA1 receptor and improving ABCA1 cholesterol-mediated efflux. Our findings suggest a beneficial effect of lyso-DGTS and its bioactive lipid derivatives on increasing HDL-mediated cholesterol efflux activity from macrophages, which may impact atherosclerosis attenuation.

Abstract 363: Endothelial Nitric Oxide Mediates Protection of Isolated Cardiomyocytes by Poloxamer 188 Against Hypoxia Reoxygenation Injury

Background: Poloxamer (P) 188, a copolymer-based cell membrane stabilizer, has been suggested to alleviate myocardial ischemia/reperfusion injury through cell membrane stabiliztion. Recent studies found that cell-to-cell interactions between endothelial cells (ECs) and cardiomyocytes (CMs) can further protect CMs: data from our co-culture model showed that ECs, at an appropriate density, promoted protection by P188 against hypoxia/reoxygenation (HR) injury evidenced by reduced release of lactate dehydrogenase (LDH) from CMs; however, the mechanism of interaction was yet to be explored. In the present study, we examined whether L-NAME, a nitric oxide (NO) synthase inhibitor, abrogates LDH release and/or Ca 2+ overload in CMs in the presence or absence of P188 and ECs. Methods: Mouse coronary artery ECs, plated at densities of 25,000 per insert, were co-cultured with mouse CMs plated at confluency on the bottom of the corresponding well. Normoxic controls were kept under normal O 2 and media conditions for 24 hours while HR groups underwent 24 h hypoxia at 0.01% O 2 in serum- and glucose-free media, followed by 2 hr reoxygenation in normal media. P188 (300 uM), L-NAME (40 mM) or vehicle were administered upon reoxygenation. Intracellular Ca 2+ and LDH release were measured by standard kits. Statistics: ANOVA and SNK, alpha = 0.05. Results: Consistent with previous observations, ECs at this low density did not affect HR-triggered LDH release or increased Ca 2+ in CMs by themselves; in the presence of P188, however, ECs were able to reduce LDH and Ca 2+ after HR (panel 1A, 2A) synergistically. L-NAME abrogated CM protection by P188 &amp; ECs in both assays (panels 1B, 2B). Neither intervention had any effect under normoxic conditions (all panels). Conclusion: The current data in this co-culture model suggest that protection of CMs by P188 is mediated through endothelial NO release.

Assessment of the anti-inflammatory mechanism of quercetin 3,7-dirhamnoside using an integrated pharmacology strategy.

Pouzolzia zeylanica (L.) Benn. is a Chinese herbal medicine widely used for its anti-inflammatory and pus-removal properties. To explore its potential anti-inflammatory mechanism, quercetin 3,7-dirhamnoside (QDR), the main flavonoid component of P. zeylanica (L.) Benn., was extracted and purified. The potential anti-inflammatory targets of QDR were predicted using network analysis. These potential targets were verified using molecular docking, molecular dynamics simulations, and invitro experiments. Consequently, 342 potential anti-inflammatory QDR targets were identified. By analyzing the intersection between the protein-protein interaction and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we identified several potential protein targets of QDR, including RAC-alpha serine/threonine-protein kinase (AKT1), Ras-related C3 botulinum toxin substrate 1 (RAC1), nitric oxide synthase 3 (NOS3), serine/threonine-protein kinase mTOR (mTOR), epidermal growth factor receptor (EGFR), growth factor receptor-bound protein 2 (GRB2), and endothelin-1 receptor (EDNRA). QDR has anti-inflammatory activity and regulates immune responses and apoptosis through chemokines, Phosphatidylinositol 3-kinase 3(PI3K)/AKT, cAMP, T-cell receptor, and Ras signaling pathways. Molecular docking analysis showed that QDR has good binding abilities with AKT1, mTOR, and NOS3. In addition, molecular dynamics simulations demonstrated that the protein-ligand complex systems formed between QDR and AKT1, mTOR, and NOS3 have high dynamic stability, and their protein-ligand complex systems possess strong binding ability. In RAW264.7 macrophages, QDR significantly inhibited lipopolysaccharides (LPS)-induced inducible nitric oxide synthase expression, nitric oxide (NO) release and the generation of proinflammatory cytokines IL-6, IL-1β, and TNF-α. QDR downregulated the expression of p-AKT1(Ser473)/AKT1 and p-mTOR (Ser2448)/mTOR, and upregulated the expression of NOS3, Rictor, and Raptor. This indicates that the anti-inflammatory mechanisms of QDR involve regulation of AKT1 and mTOR to prevent apoptosis and of NOS3 which leads to the release of endothelial NO. Thus, our study elucidated the potential anti-inflammatory mechanism of QDR, the main flavonoid found in P. zeylanica (L.) Benn.

Nitric oxide metabolites in heart failure patients with reduced or preserved ejection fraction and effects of different exercise modes

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): German Centre for Cardiovascular Research (DZHK). Background Alterations of endothelial function and nitric oxide (NO) release are involved in pathophysiology and clinical symptoms of heart failure (HF). Regular exercise training improves vascular and endothelial function and is closely linked to mechanisms of NO pathway by enhancing endothelial NO synthesis. However, it is not well investigated how exercise training affects metabolites of the NO pathway and whether different exercise modes have different effects on NO bioavailability in HF. Purpose The aims of this analysis were to 1) investigate differences in serum levels of the NO metabolites L-arginine, homoarginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) between patients with HF with reduced (HFrEF) or preserved ejection fraction (HFpEF) and 2) to investigate effects of high-intensity interval training (HIIT) and moderate continuous training (MCT) on these parameters. Methods Patients with HF from two clinical exercise intervention trials were included in this analysis. In both trials, patients were randomized (1:1:1) either to HIIT, MCT or guideline control (CG). Clinical data and blood samples were collected at baseline, after three months of supervised exercise training and after 12 months follow-up. NO metabolites were analysed from EDTA-plasma using liquid chromatography-tandem mass spectrometry (LC–MS/MS). Results Data from 366 patients with HF, including 206 HFrEF (median [1. and 3. quartile]: 61 [53;70] years, 18.9% females) and 160 HFpEF patients (71 [66;76] years, 65.6% females), was available for analysis. Patients with HFrEF or HFpEF showed no significant differences in NYHA classification (NYHA III: 30.6% vs. 26.2%, p=0.43) or presence of diabetes mellitus (23.8% vs. 26.2%, p=0.50), while HFpEF had a higher prevalence of hypertension (86.9% vs. 38.5%, p&amp;lt;0.001) but a smaller number of current smoker than HFrEF (4.4% vs. 18.0%, p&amp;lt;0.001). PeakVO2 (18.4 [14.5;22.6] ml/min/kg vs. 17.0 [14.3;20.4] ml/min/kg, p=0.03) and HDL-cholesterol (56 [46;65] mg/dl vs. 42 [36;54] mg/dl, p&amp;lt;0.001) were higher in HFpEF than in HFrEF. At baseline, homoarginine and ADMA levels were higher in HFrEF than in HFpEF, but no differences in L-arginine or SDMA could be observed (Table 1). Changes in metabolite levels from baseline to 3 and 12 months were not significantly different between groups (HIIT, MCT, CG) in either HF phenotype (all p&amp;gt;0.05). In all exercise groups, median adherence to training sessions was at 85% or above with no significant differences between groups (p&amp;gt;0.05). Conclusion At baseline, patients with HFrEF had significantly higher homoarginine and ADMA levels compared to patients with HFpEF. However, in both HF phenotypes neither MCT nor HIIT induced significant changes in serum levels of NO metabolites when compared to patients randomized to CG.

Aldosterone Synthase Inhibitors and Dietary Interventions: A Combined Novel Approach for Prevention and Treatment of Cardiovascular Disease.

Systemic hypertension (HTN) is the hallmark of cardiovascular disease and the forerunner of heart failure. These associations have been established over decades of research on essential HTN. Advancements in the treatment of patients diagnosed with HTN, consisting of alpha- or beta-adrenergic receptor blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide, or aldosterone receptor blockers known as anti-mineralocorticoids, in the presence or absence of low sodium salt diets, often fail to control blood pressure adequately to prevent morbidity and mortality. Low sodium diets have had limited success in controlling HTN because low sodium intake is associated with renin-angiotensin-aldosterone system upregulation. Therefore, upregulating aldosterone secretion, sodium, and water retention which, in turn, moves the blood pressure back toward the range of HTN dictated by the baroreceptor reset value, as a compensatory mechanism, especially in resistant HTN. These impediments to blood pressure control in HTN may have been effectively circumvented by the advent of a new class of drugs known as aldosterone synthase inhibitors, represented by baxdrostat.The mechanism of action of baxdrostat as an aldosterone synthase inhibitor demonstrates the inextricable linkage between sodium and blood pressure regulation. Theoretically, combining a low sodium diet with the activity of this aldosterone synthesis inhibitor should alleviate the adverse effect of renin-angiotensin-aldosterone system upregulation. Aldosterone synthesis inhibition should also decrease the oxidative stress and endothelial dysfunction associated with HTN, causing more endothelial nitric oxide synthesis, release, and vasorelaxation. To the best of our knowledge, this is the first systematic review to summarize evidence-based articles relevant to the use of a novel drug (aldosterone synthase inhibitor) in the treatment of HTN and cardiovascular disease. Making the current database of relevant information on baxdrostat and other aldosterone synthase inhibitors readily available will, no doubt, aid physicians and other medical practitioners in their decision-making about employing aldosterone synthase inhibitors in the treatment of patients.

UHPLC-MS Phenolic Fingerprinting, Aorta Endothelium Relaxation Effect, Antioxidant, and Enzyme Inhibition Activities of Azara dentata Ruiz & Pav Berries.

Azara dentata Ruiz & Pav. is a small Chilean native plant from Patagonia, a producer of small white reddish berries. For the first time, the proximal analysis of the fruits, phenolic fingerprinting, the antioxidant activity, and the enzymatic inhibition and relaxation effects in rat aorta induced by the ethanolic extract of these fruits were investigated. The proximal composition and the mineral (Ca: 2434 ± 40 mg/kg; Mg: 702 ± 13 mg/kg; Fe: 117.1 ± 1.6 mg/kg; Zn: 16.1 ± 0.4 mg/kg) and heavy metal (As: 121 ± 11 µg/kg; Cd: 152 ± 5 µg/kg; Hg: 7.7 ± 1.3 µg/kg; Pb 294 ± 4 µg/kg) contents were analyzed. Anthocyanins, flavonoids, phenolic acids, and coumarins were identified using UHPLC-PDA-QTOF-MS. The ethanolic extracts showed a total phenolic content of 23.50 ± 0.93 mg GAE/g extract. In addition, the antioxidant activity was assessed using both DPPH and TEAC (28.64 ± 1.87 and 34.72 ± 2.33 mg Trolox/g of dry fruit, respectively), FRAP (25.32 ± 0.23 mg Trolox equivalent/g dry fruit), and ORAC (64.95 ± 1.23 mg Trolox equivalents/g dry fruit). The inhibition of enzymatic activities (acetylcholinesterase IC50: 2.87 + 0.23 µg extract/mL, butyrylcholinesterase IC50: 6.73 + 0.07 µg extract/mL, amylase IC50: 5.6 ± 0.0 µg extract/mL, lipase IC50: 30.8 ± 0.0 µg extract/mL, and tyrosinase IC50: 9.25 ± 0.15 µg extract/mL) was also assessed. The extract showed 50-60% relaxation in rat aorta (intact), mediated thorough the release of endothelial nitric oxide. Our results suggest that A. dentata is a good source of compounds with the capacity to inhibit important enzymes, can be hypotensive, and can thus have good potentiality as supplements in the amelioration of neurodegenerative diseases and could also have potential to be used to develop new functional foods. The study highlights the benefits of these neglected small fruits and could boost their consumption.

Theophylline-induced endothelium-dependent vasodilation is mediated by increased nitric oxide release and phosphodiesterase inhibition in rat aorta.

This study aimed to examine the endothelial dependence of vasodilation induced by the phosphodiesterase inhibitor theophylline in isolated rat thoracic aortas and elucidate the underlying mechanism, with emphasis on endothelial nitric oxide (NO). The effects of various inhibitors and endothelial denudation on theophylline-induced vasodilation, and the effect of theophylline on vasodilation induced by NO donor sodium nitroprusside, cyclic guanosine monophosphate (cGMP) analog bromo-cGMP, and β-agonist isoproterenol in endothelium-denuded aorta were examined. The effects of theophylline and sodium nitroprusside on cGMP formation were also examined. We examined the effect of theophylline on endothelial nitric oxide synthase (eNOS) phosphorylation and intracellular calcium levels. Theophylline-induced vasodilation was greater in endothelium-intact aortas than that in endothelium-denuded aortas. The NOS inhibitor, NW-nitro-L-arginine methyl ester; non-specific guanylate cyclase (GC) inhibitor, methylene blue; and NO-sensitive GC inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a] quinoxalin-1-one inhibited theophylline-induced vasodilation in endothelium-intact aortas. Theophylline increased the vasodilation induced by sodium nitroprusside, bromo-cGMP, and isoproterenol. Theophylline increased cGMP formation in endothelium-intact aortas, and sodium nitroprusside-induced cGMP formation in endothelium-denuded aortas. Moreover, theophylline increased stimulatory eNOS (Ser1177) phosphorylation and endothelial calcium levels, but decreased the phosphorylation of inhibitory eNOS (Thr495). These results suggested that theophylline-induced endothelium-dependent vasodilation was mediated by increased endothelial NO release and phosphodiesterase inhibition.

Endothelial IK and SK channel activation decreases pulmonary arterial pressure and vascular remodeling in pulmonary hypertension.

Endothelial cells (ECs) from small pulmonary arteries (PAs) release nitric oxide (NO) and prostacyclin, which lower pulmonary arterial pressure (PAP). In pulmonary hypertension (PH), the levels of endothelium-derived NO and prostacyclin are reduced, contributing to elevated PAP. Small-and intermediate-conductance Ca2+-activated K+ channels (IK and SK)-additional crucial endothelial mediators of vasodilation-are also present in small PAs, but their function has not been investigated in PH. We hypothesized that endothelial IK and SK channels can be targeted to lower PAP in PH. Whole-cell patch-clamp experiments showed functional IK and SK channels in ECs, but not smooth muscle cells, from small PAs. Using a SU5416 plus chronic hypoxia (Su + CH) mouse model of PH, we found that currents through EC IK and SK channels were unchanged compared with those from normal mice. Moreover, IK/SK channel-mediated dilation of small PAs was preserved in Su + CH mice. Consistent with previous reports, endothelial NO levels and NO-mediated dilation were reduced in small PAs from Su + CH mice. Notably, acute treatment with IK/SK channel activators decreased PAP in Su + CH mice but not in normal mice. Further, chronic activation of IK/SK channels decreased PA remodeling and right ventricular hypertrophy, which are pathological hallmarks of PH, in Su + CH mice. Collectively, our data provide the first evidence that, unlike endothelial NO release, IK/SK channel activity is not altered in PH. Our results also demonstrate proof of principle that IK/SK channel activation can be used as a strategy for lowering PAP in PH.

Diosmin and its glycocalyx restorative and anti-inflammatory effects on injured blood vessels.

The endothelium, a crucial homeostatic organ, regulates vascular permeability and tone. Under physiological conditions, endothelial stimulation induces vasodilator endothelial nitric oxide (eNO) release and prevents adhesion molecule accessibility and leukocyte adhesion and migration into vessel walls. Endothelium dysfunction is a principal event in cardiovascular disorders, including atherosclerosis. Minimal attention is given to an important endothelial cell structure, the endothelial glycocalyx (GCX), a negatively charged heterogeneous polysaccharide that serves as a protective covering for endothelial cells and enables endothelial cells to transduce mechanical stimuli into various biological and chemical activities. Endothelial GCX shedding thus plays a role in endothelial dysfunction, for example by increasing vascular permeability and decreasing vessel tone. Consequently, there is increasing interest in developing therapies that focus on GCX repair to limit downstream endothelium dysfunction and prevent further downstream cardiovascular events. Here, we present diosmin (3',5,7-trihydroxy-4'-methoxyflavone-7-rhamnoglucoside), a flavone glycoside of diosmetin, which downregulates adhesive molecule expression, decreases inflammation and capillary permeability, and upregulates eNO expression. Due to these pleiotropic effects of diosmin on the vasculature, a possible unidentified mechanism of action is through GCX restoration. We hypothesize that diosmin positively affects GCX integrity along with GCX-related endothelial functions. Our hypothesis was tested in a partial ligation left carotid artery (LCA) mouse model, where the right carotid artery was the control for each mouse. Diosmin (50 mg/kg) was administered daily for 7 days, 72h after ligation. Within the ligated mice LCAs, diosmin treatment elevated the activated eNO synthase level, inhibited inflammatory cell uptake, decreased vessel wall thickness, increased vessel diameter, and increased GCX coverage of the vessel wall. ELISA showed a decrease in hyaluronan concentration in plasma samples of diosmin-treated mice, signifying reduced GCX shedding. In summary, diosmin supported endothelial GCX integrity, to which we attribute diosmin's preservation of endothelial function as indicated by attenuated expression of inflammatory factors and restored vascular tone.

Lyso-DGTS Lipid Derivatives Enhance PON1 Activities and Prevent Oxidation of LDL: A Structure-Activity Relationship Study.

Paraoxonase 1 (PON1) plays a role in regulating reverse cholesterol transport and has antioxidative, anti-inflammatory, antiapoptotic, vasodilative, and antithrombotic activities. Scientists are currently focused on the modulation of PON1 expression using different pharmacological, nutritional, and lifestyle approaches. We previously isolated a novel active compound from Nannochloropsis microalgae—lyso-diacylglyceryltrimethylhomoserine (lyso-DGTS)—which increased PON1 activity, HDL-cholesterol efflux, and endothelial nitric oxide release. Here, to explore this important lipid moiety’s effect on PON1 activities, we examined the effect of synthesized lipid derivatives and endogenous analogs of lyso-DGTS on PON1 lactonase and arylesterase activities and LDL oxidation using structure–activity relationship (SAR) methods. Six lipids significantly elevated recombinant PON1 (rePON1) lactonase activity in a dose-dependent manner, and four lipids significantly increased rePON1 arylesterase activity. Using tryptophan fluorescence-quenching assay and a molecular docking method, lipid–PON1 interactions were characterized. An inverse correlation was obtained between the lactonase activity of PON1 and the docking energy of the lipid–PON1 complex. Furthermore, five of the lipids increased the LDL oxidation lag time and inhibited its propagation. Our findings suggest a beneficial effect of lyso-DGTS or lyso-DGTS derivatives through increased PON1 activity and prevention of LDL oxidation.

Preliminary Mechanistic Study on the Trachea Smooth Muscle Relaxant Activity of Aqueous Leaf Extract of Tridax Procumbens in Male Wistar Rats.

ObjectivesAqueous leaf extract of Tridax procumbens (ALETP) has potent relaxant activity. However, this relaxant activity in respiratory smooth muscle remains uninvestigated. This study investigates the effect of ALETP on the contractile activity of tracheal smooth muscle (TSM) in adult male Wistar rats.MethodsTwelve male Wistar rats divided into 2 groups and were treated with either 100 mg/kg of ALETP (ALETP treatment group) or vehicle (distilled water; control group) through oral gavage for 4 weeks. Dose responses of TSM from the 2 groups to acetylcholine (10–9 to 10–5 M), phenylephrine (10–9 to 10–5 M), and potassium chloride (KCl; 10–9 to 10–4 M) were determined cumulatively. Furthermore, cumulative dose responses to acetylcholine (10–9 to 10–5 M) after pre-incubation of TSM with atropine (10–5 M), L-NAME (10–4 M), indomethacin (10–4 M), and nifedipine (10–4 M), were determined.ResultsTreatment with ALETP substantially inhibited TSM contraction stimulated by cumulative doses of acetylcholine, phenylephrine, and KCl. Furthermore, preincubation of TSM from the 2 groups in atropine significantly inhibited contractility in TSM. Incubation in L-NAME and indomethacin also significantly inhibited contractility in TSM of ALETP-treated rats compared to that of controls. Contractile activity of the TSM was also inhibited significantly with incubation in nifedipine in ALETP-treated rats.ConclusionALETP enhanced relaxant activity in rat TSM primarily by blocking the L-type calcium channel and promoting endothelial nitric oxide release. ALETP contains agents that may be useful in disorders of the respiratory tract.

Beneficial effects of capsaicin and dihydrocapsaicin on endothelial inflammation, nitric oxide production and antioxidant activity

Capsaicin and dihydrocapsaicin (DHC) are major pungent capsaicinoids produced in chili peppers. Capsaicin has been previously shown to promote vascular health by increasing nitric oxide (NO) production and reducing inflammatory responses. While capsaicin has been extensively studied, whether DHC exerts cardiovascular benefits through similar mechanisms remains unclear. The current study aimed to investigate the direct effects of DHC on endothelial inflammation, NO release, and free radical scavenging properties. DHC at concentrations up to 50 µM did not affect cell viability, while concentrations of 100 and 500 µM of DHC led to endothelial cytotoxicity. Capsaicin decreased cell viability at concentration of 500 µM. To investigate the effects of capsaicinoids on endothelial activation, we first demonstrated that TNFα induced Ser536 phosphorylation of p65 NFκB, expressions of adhesion molecules, vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1, and IL-6 production in primary human endothelial cells. These effects were robustly abrogated by DHC. Consistently, DHC treatment led to a marked reduction in TNFα-mediated monocyte adhesion to endothelial cells. Additionally, NO production was significantly induced by DHC and capsaicin compared to vehicle control. Similar to capsaicin and vitamin C, DHC scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) free radicals in vitro. Our present study highlights the benefits of DHC and capsaicin treatment on human endothelial cells and provides evidence to support cardiovascular benefits from capsicum consumption.

Procalcitonin mediates vascular dysfunction in obesity

AimsObesity is accompanied by a chronic low-grade inflammation associated with endothelial dysfunction and vascular complications. Procalcitonin is a marker of inflammation, secreted by adipose tissue and elevated in obese subjects. We here investigated whether visceral or perivascular fat-derived procalcitonin is a target to improve obesity-induced endothelial dysfunction. Materials and methodsProcalcitonin expression was identified by Western blot. Murine endothelial cells were isolated using CD31-antibody-coated magnetic beads and reactive oxygen species and nitric oxide (NO) determined by H2DCF- or DAF-FM diacetate loading. Endothelium-dependent vasorelaxation was analyzed using pressure myography of murine arterioles. Calcitonin gene-related peptide (CGRP) was used to activate the calcitonin receptor-like receptor (CRLR)/RAMP1 complex and olcegepant or the dipeptidyl-peptidase 4 (DPP4) inhibitor sitagliptin to block procalcitonin signaling or activation. Key findingsIn addition to visceral adipose tissue, procalcitonin was present in perivascular and epicardial tissue. In concentrations typical for obesity, procalcitonin doubled reactive oxygen species formation and decreased endothelial nitric oxide production in murine endothelial cells. Intravenous delivery of procalcitonin to mice in obesity-associated concentrations impaired endothelium-dependent vasorelaxation in a CRLR/RAMP1-dependent manner and antagonized CGRP-induced endothelial NO release in vitro. Use of CRLR/RAMP1-receptor antagonist olcegepant counteracted procalcitonin effects on vasodilation, nitric oxide production and reactive oxygen species formation. Similarly, blocking procalcitonin activation by the DPP4 inhibitor sitagliptin antagonized endothelial procalcitonin effects. SignificanceProcalcitonin, liberated either from visceral or perivascular adipose tissue, contributes to endothelial dysfunction by antagonizing CGRP signaling in obesity. Targeting hyperprocalcitonemia may be a means to preserve endothelial function and reduce comorbidity burden in obese subjects.

Pleiotropic activation of endothelial function by angiotensin II receptor blockers is crucial to their protective anti-vascular remodeling effects

There are no therapeutics that directly enhance chronic endothelial nitric oxide (NO) release, which is typically associated with vascular homeostasis. In contrast, angiotensin II (AngII) receptor type 1 (AT1R) blockers (ARBs) can attenuate AngII-mediated oxidative stress, which often leads to increased endothelial NO bioavailability. Herein, we investigate the potential presence of direct, AngII/AT1R-independent ARB class effects on endothelial NO release and how this may result in enhanced aortic wall homeostasis and endothelial NO-specific transcriptome changes. Treatment of mice with four different ARBs induced sustained, long-term inhibition of vascular contractility by up to 82% at 16 weeks and 63% at 2 weeks, an effect reversed by L-NAME and absent in endothelial NO synthase (eNOS) KO mice or angiotensin converting enzyme inhibitor captopril-treated animals. In absence of AngII or in tissues with blunted AT1R expression or incubated with an AT2R blocker, telmisartan reduced vascular tone, supporting AngII/AT1R-independent pleiotropism. Finally, telmisartan was able to inhibit aging- and Marfan syndrome (MFS)-associated aortic root widening in NO-sensitive, BP-independent fashions, and correct aberrant TGF-β signaling. RNAseq analyses of aortic tissues identified early eNOS-specific transcriptome reprogramming of the aortic wall in response to telmisartan. This study suggests that ARBs are capable of major class effects on vasodilatory NO release in fashions that may not involve blockade of the AngII/AT1R pathway. Broader prophylactic use of ARBs along with identification of non-AngII/AT1R pathways activated by telmisartan should be investigated.