Vasodilator Molecule Research Articles

Modulation of pain in pediatric sickle cell disease: understanding the balance between endothelin mediated vasoconstriction and apelin mediated vasodilation.

Children with sickle cell disease (SCD) have painful vaso-occlusive episodes (VOEs), which often reoccur across the individual's lifespan. Vaso-constrictive and vaso-dilatory molecules have been hypothesized to play a role in VOEs. Endothelin-1 (ET-1) is a potent vasoconstrictor that is released during VOEs and is correlated with pain history. Apelin is a vaso-dilatory peptide that also has a modulatory role in pain processing. We hypothesize that the ratio between vaso-dilatory and vaso-constrictive tone in children with SCD may be a marker of pain sensitization and vaso-occlusion. Plasma endothelin and apelin levels were measured in 47 children with SCD. Procedural pain and baseline pain were assessed via child- and caregiver-reports and observational distress. Pain history was assessed using retrospective chart review. Plasma apelin was related to age, with decreased levels in older children. The ratio between apelin and ET-1 was negatively correlated to observational baseline pain. The ratio between apelin and Big ET was negatively correlated to caregiver ratings of baseline pain and positively correlated to history of VOEs, which is possibly due to hydroxyurea treatment. These results suggest that an imbalance in the apelin and endothelin systems may contribute to an increasing number of VOEs and baseline pain in children with SCD.

Organic nitrates: past, present and future.

Nitric oxide (NO) is one of the most important vasodilator molecules produced by the endothelium. It has already been established that NO/cGMP signaling pathway deficiencies are involved in the pathophysiological mechanisms of many cardiovascular diseases. In this context, the development of NO-releasing drugs for therapeutic use appears to be an effective alternative to replace the deficient endogenous NO and mimic the role of this molecule in the body. Organic nitrates represent the oldest class of NO donors that have been clinically used. Considering that tolerance can occur when these drugs are applied chronically, the search for new compounds of this class with lower tolerance potential is increasing. Here, we briefly discuss the mechanisms involved in nitrate tolerance and highlight some achievements from our group in the development of new organic nitrates and their preclinical application in cardiovascular disorders.

Physiological mechanisms of vascular response induced by shear stress and effect of exercise in systemic and placental circulation.

Physiological vascular function regulation is essential for cardiovascular health and depends on adequate control of molecular mechanisms triggered by endothelial cells in response to mechanical and chemical stimuli induced by blood flow. Endothelial dysfunction is one of the main risk factors of cardiovascular pathology, where the imbalance between the synthesis of vasodilator and vasoconstrictor molecules is common in the development of vascular disorders in systemic and placental circulation. In the placenta, an organ without autonomic innervations, the local control of vascular tone is critical for maintenance of fetal growth and mechanisms that underlie shear stress response induced by blood flow are essential during pregnancy. In this field, shear stress induced by moderate exercise is one of the most important mechanisms to improve vascular function through nitric oxide synthesis and stimulation of mechanical response of endothelial cells triggered by ion channels, caveolae, endothelial NO synthase, and vascular endothelial growth factor, among others. The demand for oxygen and nutrients by tissues and organs, especially in placentation and pregnancy, determines blood flow parameters, and physiological adaptations of vascular beds for covering metabolic requirements. In this regard, moderate exercise versus sedentarism shows potential benefits for improving vascular function associated with the enhancement of molecular mechanisms induced by shear stress. In this review, we collect evidence about molecular bases of physiological response to shear stress in order to highlight the relevance of moderate exercise-training for vascular health in adult and fetal life.

New insights into the steen solution properties: breakthrough in antioxidant effects via NOX2 downregulation.

Ex vivo lung perfusion (EVLP) allows perfusion and reconditioning of retrieved lungs for organ transplantation. The Steen solution is specifically designed for this procedure but the mechanism through which it elicits its activity is still to be fully clarified. We speculated that Steen solution may encompass antioxidant properties allowing a reestablishment of pulmonary tissue homeostasis. Blood samples from 10 healthy volunteers were recruited. Platelets and white cells were incubated with Steen solution or buffer solution as control and stimulated with suitable agonists. Reactive oxidant species (ROS), soluble NOX2 (sNOX2-derived peptide), a marker of NADPH oxidase activation, p47phox translocation to cell membrane and isoprostanes production, as marker of oxidative stress, and nitric oxide (NO), a powerful vasodilator and antioxidant molecule, were measured upon cell stimulation. The Steen solution significantly inhibited p47phox translocation and NOX2 activation in platelets and white cells. Consistent with this finding was the reduction of oxidative stress as documented by a significantly lowered formation of ROS and isoprostanes by both platelets and white cells. Finally, cell incubation with Steen solution resulted in enhanced generation of NO. Herewith, we provide the first evidence that Steen solution possesses antioxidant properties via downregulation of NADPH oxidase activity and enhanced production of NO.

Adrenomedullin: a vasodilator to treat sepsis?

Adrenomedullin is a vasodilatory polypeptide with pleiotropic effects secreted by various organs. Adrenomedullin is produced first as a prepropeptide, and then cleaved into mature adrenomedullin and mid-regional proadrenomedullin. Whereas levels of the latter have been shown to correlate with severity of sepsis and carry prognostic value, adrenomedullin plays a role in vascular tone homeostasis. In the previous issue of Critical Care, the infusion of exogenous adrenomedullin is suggested to protect against increased lung endothelial permeability and end-organ dysfunction in a model of pneumococcal pneumonia in mechanically ventilated mice, possibly by stabilizing vascular endothelia. Since adrenomedullin is a strong vasodilatory molecule, further studies are needed to evaluate its potential as a future treatment of sepsis.

Generation of HNO and HSNO from Nitrite by Heme‐Iron‐Catalyzed Metabolism with H2S

Nitrite has been shown in the past decade to be an important source of nitric oxide that acts as a vasodilator and intrinsic signaling molecule. Numerous studies have proved that nitrite can be reduced in vivo, either non-enzymatically or enzymatically, in reactions catalyzed by xanthine oxidase, deoxyhaemoglobin, deoxymyoglobin, cytochrome c, or by thiol and metal-center-assisted processes inside the cell. The mechanism of the last process has recently been studied in detail, and has demonstrated that thiols (cysteine and gluthathione) stimulate water-soluble Fe-porphyrins to have nitrite reductase activity through an oxygen atom transfer (OAT)mechanism (Scheme 1) that leads to increased

Abstract 231: Hydrogen Sulfide Treatment Reduces Hyperglycemic Effects via Activation of Adenosine Monophosphate Activated Protein Kinase In Vitro

Hydrogen sulfide (H 2 S) is well known as a potent vasodilator and signaling molecule under normal and pathophysiological conditions. Previously, we reported that in hyperglycemia (HG), impairment of cystathionine β synthase/ cystathionine lyase (CBS/CSE) decreases H 2 S production leading to vascular remodeling. Treatment with H 2 S mitigated the adverse effects; however, its precise mechanism was unknown. Literature reports suggest that hyperglycemia suppresses adenosine monophosphate-activated protein kinase (AMP-K) pathway and increases autophagy leading to extracellular matrix (ECM) remodeling. Liver kinase B1 (LKB1) is a protein kinase which has been reported to control the activity of AMP-K. Activation of LKB1, in turn, is regulated by two pseudokinases, STE-20 related protein (STRAD) and mouse protein-25 (MO25). In this study, we hypothesized that H 2 S mediates its effects by the formation of a tri-molecular complex (STRAD/MO25/LKB1) leading to the activation of AMP-K and modulation of autophagy. Mouse glomerular endothelial cells were used in this study. Under normoglycemic (NG) and HG conditions, cells were treated without or with H 2 S and activators/inhibitors of the signaling molecules above. The expression of CBS/CSE was diminished by 3-fold under HG compared to NG. H 2 S production was also decreased [3.5 vs. 7.2 μM/L (HG vs. NG)]. HG decreased LKB1 by 5-fold and AMP-K by 14-fold compared to NG. Autophagy marker LC3A/B ratio was similarly decreased in HG. The expression of periostin, a marker of renal disease progression, was higher (Relative intensity (RI) = 1.9 ± 0.64) in HG compared to NG (RI= 1.4 ± 0.18). In HG, administration of H 2 S activated STRAD by 4-fold and MO25 by 3-fold causing concomitant phosphorylation of LKB1 (5-fold increase) eventually leading to AMP-K phosphorylation (13-fold increase). Interestingly, phosphorylated AMP-K inhibited autophagy and reduced ECM protein accumulation. Our findings suggest that the protective effect of exogenous H 2 S in hyperglycemia is mediated by AMP-K activation involving STRAD and MO25 pseudokinases.

Endothelial TLR4 activation impairs intestinal microcirculatory perfusion in necrotizing enterocolitis via eNOS–NO–nitrite signaling

Necrotizing enterocolitis (NEC) is a devastating disease of premature infants characterized by severe intestinal necrosis and for which breast milk represents the most effective protective strategy. Previous studies have revealed a critical role for the lipopolysaccharide receptor toll-like receptor 4 (TLR4) in NEC development through its induction of mucosal injury, yet the reasons for which intestinal ischemia in NEC occurs in the first place remain unknown. We hypothesize that TLR4 signaling within the endothelium plays an essential role in NEC development by regulating perfusion to the small intestine via the vasodilatory molecule endothelial nitric oxide synthase (eNOS). Using a unique mouse system in which we selectively deleted TLR4 from the endothelium, we now show that endothelial TLR4 activation is required for NEC development and that endothelial TLR4 activation impairs intestinal perfusion without effects on other organs and reduces eNOS expression via activation of myeloid differentiation primary response gene 88. NEC severity was significantly increased in eNOS(-/-) mice and decreased upon administration of the phosphodiesterase inhibitor sildenafil, which augments eNOS function. Strikingly, compared with formula, human and mouse breast milk were enriched in sodium nitrate--a precursor for enteral generation of nitrite and nitric oxide--and repletion of formula with sodium nitrate/nitrite restored intestinal perfusion, reversed the deleterious effects of endothelial TLR4 signaling, and reduced NEC severity. These data identify that endothelial TLR4 critically regulates intestinal perfusion leading to NEC and reveal that the protective properties of breast milk involve enhanced intestinal microcirculatory integrity via augmentation of nitrate-nitrite-NO signaling.

Spinal Cord Stimulation for Chronic Limb Ischemia

The treatment of chronic limb ischemia involves the restoration of pulsatile blood flow to the distal extremity. Some patients cannot be treated with endovascular means or with open surgery; some may have medical comorbidities that render them unfit for surgery, while others may have persistent ischemia or pain even in the face of previous attempts at reperfusion. In spinal cord stimulation (SCS), a device with electrodes is implanted in the epidural space to stimulate sensory fibers. This activates cell-signaling molecules that in turn cause the release of vasodilatory molecules, a decrease in vascular resistance, and relaxation of smooth muscle cells. SCS also suppresses sympathetic vasoconstriction and pain transmission. When patient selection is based on microcirculatory parameters, SCS therapy can significantly improve pain relief, halt the progression of ulcers, and potentially achieve limb salvage.

Targeting the high‐conductance Ca2+‐activated K+ (BK) channel as vasodilator therapy for pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by a loss of nitric oxide, prostacyclin, and other vasodilator molecules resulting in pulmonary vasoconstriction. In contrast, our Western blot studies detected a 4.9‐fold increase in expression of the high‐conductance Ca2+‐activated K+ (BK) channel in the pulmonary arteries (PA) of rats with hypoxia‐induced PAH (n=6), suggesting the upregulation of a potent vasodilator influence. However, it is possible that BK channels are inactivated in hypoxia‐induced PAH, since RT‐PCR confirmed that the BK α‐subunit in rat PA contains a hypoxia‐sensitive STREX region known to negatively regulate channel activity. Considering these factors, we hypothesized that pharmacological activation of over‐expressed BK channels in the VSMCs of affected PA may enact vasodilation as a therapy for PAH. Patch‐clamp studies showed that NS11021 (1, 3 and 10 μmol/L), a novel pharmacological BK channel opener, increased whole‐cell K+ current by 1.9‐fold in VSMCs of PA from control rats (n=3). Similar concentrations of NS11021 also partially reversed hypoxia‐induced constrictions of rat PA rings in tension‐recording studies (n=3). These results suggest that BK channel openers represent a potential vasodilator therapy for PAH, a hypothesis we plan to test using pulmonary biotelemetry in rat models of PAH. Supported by UL1RR029884 (NDD) from the NIH.

English

Introduction Flow-mediated dilatation (FMD) is widely used as a non-invasive method to assess endothelial function. Vascular endothelium is a biological interface between blood and vessel wall and has a crucial role in vascular homeostasis. The endothelium is a large paracrine organ that secretes numerous factors regulating vasomotor function, cell growth, platelet and leukocyte interactions, inflammatory responses and thrombosis. It responds to various internal and external stimuli, through cell membrane receptors and signal transduction mechanisms, with numerous vasoactive substances released, including prostacyclins, endothelins, endothelial cell growth factors, interleukins, plasminogen inhibitors and nitric oxide (NO). In particular, NO is one of the most important molecules for its role as a vasodilator factor, inhibitor of inflammatory activity, vascular smooth muscle cell proliferation and platelet adhesion and aggregation. Classic and non-classic atherosclerotic risk factors such as hypertension, diabetes mellitus, smoking habit, obesity, dyslipidemia and systemic inflammation could lead to endothelial dysfunction and accelerated atherosclerosis. Chronic inflammatory rheumatic diseases have been associated with decreased endothelial function and accelerated atherosclerosis. This paper briefly reviews the role of FMD as a surrogate marker of endothelial function in rheumatic diseases. Conclusion FMD is a useful marker of endothelial function in chronic rheumatoid disease, but many factors can affect FMD assessment, and so further studies are needed to increase our understanding. Introduction Vessel homeostasis is determined by a balance between vasoconstrictor, vasodilator, proaggregating and antiaggregating molecules. Stimuli that alter vessel homeostasis can induce an altered endothelial function. This pathophysiological condition is associated with activated phenotype of endothelial cells, leading to increased expression of adhesion molecules, proinflammatory cytokines such as tumour necrosis factor (TNF) alpha, interleukin (IL)-1, IL-6 and interferon (IFN) gamma and prothrombotic factors. This process results in oxidative stress up-regulation, loss of vasodilatory ability and promotion of thrombosis, inflammation and cellular proliferation1. Several studies demonstrated that endothelial dysfunction plays a central role in the pathogenesis of atherosclerosis, promotes early atherosclerotic changes and is predictive for the development of cardiovascular events2,3. Thus, assessment of endothelium function, in the preclinical stage of atherosclerosis with non-invasive approaches, may serve as a valuable measure to be counted in the follow-up of patients with cardiovascular disease (CVD) risk. Among different methods, the assessment of flow-mediated dilatation (FMD) is one of the most used4. FMD depends on endothelium production of vasodilator molecules including nitric oxide (NO) and prostacyclin. Assessment of FMD is based on the reactive hyperaemia phenomenon that occurs when arterial blood flow is restored after a period of transient arterial occlusion5. Increased blood flow determines an enhancement in shear stress on the vessel wall that stimulates the release of NO5,6. Endothelial cell membrane contains calcium-activated potassium channels that open in response to shear stress. Potassium entrance hyperpolarizes the cell and increases calcium entry with activation of endothelial nitric oxide synthase (eNOS)7. FMD response is characteristically presented as a change in arterial baseline diameter after hyperaemia induced by applying sphygmomanometer cuff inflated to a pressure 25–50 mmHg above systolic arterial pressure. Usually, brachial artery can be assessed for its accessibility4 (Figures 1–3). * Corresponding author Email: a.spadaro.reuma@virgilio.it 1 Dipartimento di Medicina Interna e Specialita Mediche – UOC Reumatologia Sapienza – University of Rome, Italy 2 Dipartimento di Medicina e di Scienze per la Salute, University of Molise, Campobasso, Italy Figure 1: FMD execution technique: US probe was applied on the patient’s forearm to detect brachial artery.

Soluble Vascular Cell Adhesion Molecule Levels, Endothelin-1 and Endothelial Nitric Oxide Synthase Gene Polymorphisms: Association with Clinical Symptoms in Sickle Cell Anemia.

AbstractAbstract 2118 Introduction:Vascular occlusions trigger most of the acute and chronic sickle cell anemia (HbSS) clinical complications and have been associated with high levels of soluble adhesion molecules and leukocytes activation. Accumulated evidence from clinical and experimental data shows that endothelin-1 (ET-1) plays an important role in the pathophysiology of the vascular system, because of its vasoconstrictor and hypertrophic activities. Endothelial nitric oxide synthase (eNOS) is an enzyme involved in nitric oxide (NO) synthesis pathway, a potent vasodilator and anti-inflammatory molecule. Polymorphisms in ET-1 and eNOS genes are associated with disturbance in ET-1 production and with reduced NO production respectively. The aim of this study was investigate the ET-1 5665G>T gene polymorphism and eNOS 786T>C gene promoter polymorphism with levels of soluble Intercellular Adhesion Molecule 1 (sICAM-1) and soluble Vascular Cell Adhesion Molecule 1 (sVCAM-1), biochemical markers and medical history of HbSS patients. Patients and Methods:We studied 51 HbSS patients from Northeast Brazil in attendance of the outpatient's clinic of the Foundation of Hematology and Hemotherapy of Bahia (HEMOBA). Biochemical analyses were measured by colorimetric methods, soluble adhesion molecules were measured by ELISA and the complete medical history was recorded by patient's record. The study was approved by the FIOCRUZ ethical committee and informed consents were signed by patients or official responsible.cerqueira Results:Our results showed genotype frequencies of 62.7% (32/51) of wild type (GG), 35.3% (18/51) of heterozygous (GT) and 2% (1/51) of homozygous (TT) for ET-1 5665G>T gene polymorphism. The eNOS 786T>C gene polymorphism showed 60.5% (23/38) of wild type, 34.2% (13/38) of heterozygous and 5.3% (2/38) homozygous. Both polymorphisms were in Hardy-Weinberg equilibrium. HbSS patients carriers of eNOS mutant allele (C) had the highest levels of sVCAM-1 (p= 0.015) (Fig. 1). Levels of sICAM were not related to any studied gene polymorphism. However, regarding to patients clinical history, we found a raised occurrence of acute chest syndrome (ACS) in carries of the ET-1 5665G>T mutant allele (Fig. 2). Discussion and Conclusion:Our study suggests that eNOS 786T>C and ET-1 5665G>T gene polymorphisms can participate of the HbSS pathophysiology. It is well known that high levels of circulating sVCAM are associating to an increased inflammatory state and VOC susceptibility, and our data show that eNOS variant in HbSS patients might be important to NO activity and anti-inflammatory vascular process. Also, the raised frequency of ACS, a major clinical feature in SCA which leads to patient mortality, was associated with the ET-1 variant showing the importance of the studied genes screening and their participation in these key molecules mechanism related to vascular health and VOC process. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

L-Arginine Transport and Nitric Oxide Synthesis in Human Endothelial Progenitor Cells

Nitric oxide (NO) is an endogenous vasodilator molecule synthetized from L-arginine by a family of nitric oxide synthases. In differentiated human endothelial cells, it is well known that L-arginine uptake via cationic amino acid transporters (y(+)/CAT) or system y(+)L is required for the NO synthesis via endothelial nitric oxide synthase, but there are no reports in human endothelial progenitor cell (hEPC). Therefore, we isolated hEPCs from peripheral blood of healthy donors and cultured them for either 3 (hEPC-3d) or 14 days (hEPC-14d) to characterize the L-arginine transport and NO synthesis in those cells. L-arginine transport and NO synthesis were analyzed in the presence or absence of N-ethylmaleimide or L-nitroarginine methyl ester, as inhibitors of y(+)/CAT system and nitric oxide synthases, respectively. The results showed that L-arginine uptake is higher in hEPC-14d than in hEPC-3d. Kinetic parameters for L-arginine transport showed the existence of at least 2 transporter systems in hEPC: a high affinity transporter system (K(m)= 4.8 ± 1.1 μM for hEPC-3d and 6.1 ± 2.4 μM for hEPC-14d) and a medium affinity transporter system (K(m) = 85.1 ± 4.0 μM for hEPC-3d and 95.1 ± 8 μM for hEPC-14d). Accordingly, hEPC expressed mRNA and protein for CAT-1 (ie, system y(+)) and mRNA for 2 subunits of y(+)L system, yLAT1, and 4F2hc. Higher L-citruline production and NO bioavailability (4-fold), and endothelial nitric oxide synthase expression (both mRNA and protein) were observed in hEPC-14d compared with hEPC-3d. Finally, the high L-citruline formation observed in hEPC-14d was blocked by N-ethylmaleimide. In conclusion, this study allowed to identity a functional L-arginine/NO pathway in two hEPC differentiation stages, which improves the understanding of the physiology of these precursor cells.

The importance of l-arginine metabolism modulation in diabetic patients with distal symmetric polyneuropathy

BackgroundMicro and macrovascular disease is the most frequent cause of morbidity and mortality of the patients with diabetes mellitus. The resent investigations have pointed out the relationship between endothelial dysfunction and the progression of these diabetic complications, suggesting the crucial role of nitric oxide, vasodilator molecule of endothelial origin, in these events, including diabetic symmetric polyneuropathy. Material and methodsThe present study encompassed 100 individuals with diabetes mellitus type II and diabetic distal symmetric polyneuropathy (DSP). Nitrate+nitrite concentration, 3-nitrotyrosine, S-nitrosothiols, ADMA and SDMA levels and arginase activity were determined compared to the control group consisted of 50 age and sex matched voluntary blood donors. ResultsNO2+NO3 concentrations, as well as 3-nitrotyrosine, S-nitrosothiol, ADMA and SDMA levels were significantly higher in patients with DSP compared to the control group. Plasma arginase activity in the patients with diabetic DSP was significantly lower compared to the values in plasma of control subjects. ConclusionThe obtained results confirmed that nitrate+nitrite, 3-nitrotyrosine, S-nitrosothiols, ADMA, SDMA and arginase activity determination in plasma of patients with diabetic DSP could be useful in monitoring the disease development and in assesing the therapy effects.

L-arginine transport and nitric oxide synthesis in human endothelial progenitor cells

Nitric oxide (NO) is an endogenous vasodilator molecule synthetized from L-arginine by a family of nitric oxide synthases. In differentiated human endothelial cells, it is well known that L-arginine uptake via cationic amino acid transporters (y(+)/CAT) or system y(+)L is required for the NO synthesis via endothelial nitric oxide synthase, but there are no reports in human endothelial progenitor cell (hEPC). Therefore, we isolated hEPCs from peripheral blood of healthy donors and cultured them for either 3 (hEPC-3d) or 14 days (hEPC-14d) to characterize the L-arginine transport and NO synthesis in those cells. L-arginine transport and NO synthesis were analyzed in the presence or absence of N-ethylmaleimide or L-nitroarginine methyl ester, as inhibitors of y(+)/CAT system and nitric oxide synthases, respectively. The results showed that L-arginine uptake is higher in hEPC-14d than in hEPC-3d. Kinetic parameters for L-arginine transport showed the existence of at least 2 transporter systems in hEPC: a high affinity transporter system (K(m)= 4.8 ± 1.1 μM for hEPC-3d and 6.1 ± 2.4 μM for hEPC-14d) and a medium affinity transporter system (K(m) = 85.1 ± 4.0 μM for hEPC-3d and 95.1 ± 8 μM for hEPC-14d). Accordingly, hEPC expressed mRNA and protein for CAT-1 (ie, system y(+)) and mRNA for 2 subunits of y(+)L system, yLAT1, and 4F2hc. Higher L-citruline production and NO bioavailability (4-fold), and endothelial nitric oxide synthase expression (both mRNA and protein) were observed in hEPC-14d compared with hEPC-3d. Finally, the high L-citruline formation observed in hEPC-14d was blocked by N-ethylmaleimide. In conclusion, this study allowed to identity a functional L-arginine/NO pathway in two hEPC differentiation stages, which improves the understanding of the physiology of these precursor cells.

An Insight into the Sialotranscriptome of Triatoma matogrossensis, a Kissing Bug Associated with Fogo Selvagem in South America

Triatoma matogrossensis is a Hemiptera that belongs to the oliveirai complex, a vector of Chagas' disease that feeds on vertebrate blood in all life stages. Hematophagous insects' salivary glands (SGs) produce potent pharmacologic compounds that counteract host hemostasis, including anticlotting, antiplatelet, and vasodilatory molecules. Exposure to T. matogrossensis was also found to be a risk factor associated with the endemic form of the autoimmune skin disease pemphigus foliaceus, which is described in the same regions where Chagas' disease is observed in Brazil. To obtain a further insight into the salivary biochemical and pharmacologic diversity of this kissing bug and to identify possible allergens that might be associated with this autoimmune disease, a cDNA library from its SGs was randomly sequenced. We present the analysis of a set of 2,230 (SG) cDNA sequences, 1,182 of which coded for proteins of a putative secretory nature.

Tetrahydrobiopterin, L-Arginine and Vitamin C Act Synergistically to Decrease Oxidant Stress and Increase Nitric Oxide That Increases Blood Flow Recovery after Hindlimb Ischemia in the Rat

Nitric oxide (NO) derived from endothelial nitric oxide synthase (eNOS) is a potent vasodilator and signaling molecule that plays essential roles in neovascularization. During limb ischemia, decreased NO bioavailability occurs secondary to increased oxidant stress, decreased L-arginine and tetrahydrobiopterin. This study tested the hypothesis that dietary cosupplementation with tetrahydrobiopterin (BH4), L-arginine and vitamin C acts synergistically to decrease oxidant stress, increase NO and thereby increase blood flow recovery after hindlimb ischemia. Rats were fed normal chow, chow supplemented with BH4 or L-arginine (alone or in combination) or chow supplemented with BH4 + L-arginine + vitamin C for 1 wk before induction of hindlimb ischemia. In the is-chemic hindlimb, cosupplementation with BH4 + L-arginine resulted in greater eNOS and phospho-eNOS (P-eNOS) expression, Ca(2+)-dependent NOS activity and NO concentration in the ischemic calf region (gastrocnemius), as well as greater NO concentration in the region of collateral arteries (gracilis). Rats receiving cosupplementation of BH4 + L-arginine led to greater recovery of foot perfusion and greater collateral enlargement than did rats receiving either agent separately. The addition of vitamin C to the BH4 + L-arginine regimen further increased these dependent variables. In addition, rats given all three supplements showed significantly less Ca(2+)-independent activity, less nitrotyrosine accumulation, greater glutathione (GSH)-to-glutathione disulfide (GSSG) ratio and less gastrocnemius muscle necrosis, on both macroscopic and microscopic levels. In conclusion, co-supplementation with BH4 + L-arginine + vitamin C significantly increased blood flow recovery after hindlimb ischemia by reducing oxidant stress, increasing NO bioavailability, enlarging collateral arteries and reducing muscle necrosis. Oral cosupplementation of BH4, L-arginine and vitamin C holds promise as a biological therapy to induce collateral artery enlargement.

Tetrahydrobiopterin, L-Arginine and Vitamin C Act Synergistically to Decrease Oxidative Stress, Increase Nitric Oxide and Improve Blood Flow after Induction of Hindlimb Ischemia in the Rat

Nitric oxide (NO) derived from endothelial nitric oxide synthase (eNOS) is a potent vasodilator and signaling molecule that plays an essential role in vascular remodeling of collateral arteries and perfusion recovery in response to hindlimb ischemia. In ischemic conditions, decreased NO bioavailability was observed because of increased oxidative stress, decreased L-arginine and tetrahydrobiopterin. This study tested the hypothesis that dietary cosupplementation with tetrahydrobiopterin (BH4), L-arginine, and vitamin C acts synergistically to decrease oxidative stress, increase nitric oxide and improve blood flow in response to acute hindlimb ischemia. Rats were fed normal chow, chow supplemented with BH4 or L-arginine (alone or in combination) or chow supplemented with BH4 + L-arginine + vitamin C for 1 wk before induction of unilateral hindlimb ischemia. Cosupplementation with BH4 + L-arginine resulted in greater eNOS expression, Ca²⁺-dependent NOS activity and NO concentration in gastrocnemius from the ischemic hindlimb, as well as greater recovery of foot perfusion and more collateral artery enlargement than did rats receiving either agent separately. The addition of vitamin C to the BH4 + L-arginine regimen did further increase these dependent variables, although only the increase in eNOS expression reached statistical significances. In addition, rats given all three supplements demonstrated significantly less Ca²⁺-independent activity, less nitrotyrosine accumulation, greater glutathione:glutathione disulfide (GSH:GSSG) ratio and less gastrocnemius muscle necrosis, on both macroscopic and microscopic levels. In conclusion, cosupplementation with BH4 + L-arginine + vitamin C significantly increased vascular perfusion after hindlimb ischemia by increasing eNOS activity and reducing oxidative stress and tissue necrosis. Oral cosupplementation of L-arginine, BH4 and vitamin C holds promise as a biological therapy to induce collateral artery enlargement.

Gene expression of adipose tissue, endothelial cells and platelets in subjects with metabolic syndrome (Review)

Metabolic syndrome is a combination of medical disorders including hypertension, dyslipidemia, hyperglycemia, insulin resistance and increased waist circumference, and is associated with a higher risk of cardiovascular disease. An increase in adipose tissue mass is associated with the augmented secretion of certain adipokines, such as interleukin-6, tumor necrosis factor-α and resistin, which cause endothelial dysfunction (an increase in vasoconstrictor molecules and in the expression of adhesion molecules as well as a decrease of vasodilator molecules, amongst other features) and hemostasis alterations that also favor a prothrombotic state (increased fibrinogen and plasminogen activator inhibitor-1 concentrations and platelet activation/aggregation). This interaction between adipose tissue, endothelial cells and platelets is associated with an increase or decrease in the expression of several transcription factors (peroxisome proliferator-activated receptors, CCAAT-enhancer-binding proteins, carbohydrate responsive element-binding proteins and sterol regulatory element-binding proteins) that play a crucial role in the regulation of distinct metabolic pathways related to the metabolic syndrome. In the present review, we present the primary changes in adipose tissue, endothelial cells and platelets in subjects with metabolic syndrome and their possible target sites at the gene expression level.

Endothelial dysfunction in the regulation of cirrhosis and portal hypertension

AbstractPortal hypertension is caused by an increased intrahepatic resistance, a major consequence of cirrhosis. Endothelial dysfunction in liver sinusoidal endothelial cells (LSECs) decreases the production of vasodilators, such as nitric oxide, and favours vasoconstriction. This contributes to an increased vascular resistance in the intrahepatic/sinusoidal microcirculation and develops portal hypertension. Portal hypertension, in turn, causes endothelial dysfunction in the extrahepatic, i.e. splanchnic and systemic, circulation. Unlike dysfunction in LSECs, endothelial dysfunction in the splanchnic and systemic circulation causes overproduction of vasodilator molecules, leading to arterial vasodilation. In addition, portal hypertension leads to the formation of portosystemic collateral vessels. Both arterial vasodilation and portosystemic collateral vessel formation exacerbate portal hypertension by increasing the blood flow through the portal vein. Pathological consequences, such as oesophageal varices and ascites, result. While the sequence of pathological vascular events in cirrhosis and portal hypertension has been elucidated, the underlying cellular and molecular mechanisms causing endothelial dysfunctions are not yet fully understood. This review article summarizes the current cellular and molecular studies on endothelial dysfunctions found during the development of cirrhosis and portal hypertension with a focus on the intra‐ and extrahepatic circulations. The article ends by discussing the future directions of the study for endothelial dysfunction.