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Mitochondrial respiration has never been directly examined in intact cerebral arteries. We tested the hypothesis that mitochondrial energetics of large cerebral arteries ex vivo are sex dependent. The Seahorse XFe24 analyzer was used to examine mitochondrial respiration in isolated cerebral arteries from adult male and female Sprague-Dawley rats. We examined the role of nitric oxide (NO) on mitochondrial respiration under basal conditions, using Nω-nitro-l-arginine methyl ester, and following pharmacological challenge using diazoxide (DZ), and also determined levels of mitochondrial and nonmitochondrial proteins using Western blot, and vascular diameter responses to DZ. The components of mitochondrial respiration including basal respiration, ATP production, proton leak, maximal respiration, and spare respiratory capacity were elevated in females compared with males, but increased in both male and female arteries in the presence of the NOS inhibitor. Although acute DZ treatment had little effect on mitochondrial respiration of male arteries, it decreased the respiration in female arteries. Levels of mitochondrial proteins in Complexes I–V and the voltage-dependent anion channel protein were elevated in female compared with male cerebral arteries. The DZ-induced vasodilation was greater in females than in males. Our findings show that substantial sex differences in mitochondrial respiratory dynamics exist in large cerebral arteries and may provide the mechanistic basis for observations that the female cerebral vasculature is more adaptable after injury.

Previous clinical trials suggested that inhaled nitric oxide (iNO) could have beneficial effects in sickle cell disease (SCD) patients with acute chest syndrome (ACS). To determine whether iNO reduces treatment failure rate in adult patients with ACS, we conducted a prospective, double-blind, randomized, placebo-controlled clinical trial. iNO (80 ppm, N = 50) gas or inhaled nitrogen placebo (N = 50) was delivered for 3 days. The primary end point was the number of patients with treatment failure at day 3, defined as any one of the following: (1) death from any cause, (2) need for endotracheal intubation, (3) decrease of PaO2/FiO2 ≥ 15 mmHg between days 1 and 3, (4) augmented therapy defined as new transfusion or phlebotomy. The two groups did not differ in age, gender, genotype, or baseline characteristics and biological parameters. iNO was well tolerated, although a transient decrease in nitric oxide concentration was mandated in one patient. There was no significant difference in the primary end point between the iNO and placebo groups [23 (46 %) and 29 (58 %); odds ratio (OR), 0.8; 95 % CI, 0.54–1.16; p = 0.23]. A post hoc analysis of the 45 patients with hypoxemia showed that those in the iNO group were less likely to experience treatment failure at day 3 [7 (33.3 %) vs 18 (72 %); OR = 0.19; 95 % CI, 0.06–0.68; p = 0.009]. iNO did not reduce the rate of treatment failure in adult SCD patients with mild to moderate ACS. Future trials should target more severely ill ACS patients with hypoxemia. NCT00748423.

Smooth muscle cells (SMC) and endothelial cells are the major cell types in blood vessels. The principal function of vascular SMC in the body is to regulate blood flow and pressure through contraction and relaxation. The endothelium performs a crucial role in maintaining vascular integrity by achieving whole-organ metabolic homeostasis via the production of factors associated with vasoconstriction or vasorelaxation. In this review, we have focused on the production of nitric oxide (NO), a vasorelaxation factor. The extent of NO production represents a key marker in vascular health. A decrease in NO is capable of inducing pathological conditions associated with endothelial dysfunction, such as obesity, diabetes, cardiovascular disease, and atherosclerosis. Recent studies have strongly implicated the involvement of G-protein-coupled receptor kinase 2 (GRK2) in the progression of cardiovascular disease. Vasculature which is affected by insulin resistance and type 2 diabetes expresses high levels of GRK2, which may induce endothelial dysfunction by reducing intracellular NO. GRK2 activation also induces changes in the subcellular localization of GRK2 itself and also of β-arrestin 2, a downstream protein. In this review, we describe the pathophysiological mechanisms of insulin resistance and diabetes, focusing on the signal transduction for NO production via GRK2 and β-arrestin 2, providing novel insights into the potential field of translational investigation in the treatment of diabetic complications.

Purpose To clarify the vasodilatory mechanism of unoprostone isopropyl (UI), we examined its effects on the retinal microvascular diameter to determine the dependence on the endothelium and/or smooth muscle to reveal the signaling mechanisms involved in this vasomotor activity. Methods Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro. Video microscopic techniques recorded the diametric responses to UI. Results The retinal arterioles dilated in response to UI in a dose-dependent (100 pM-10 µM) manner. The nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) inhibited UI-induced vasodilation. The large-conductance Ca2+-activated K channel (BKCa channel) blocker iberiotoxin also inhibited UI-induced vasodilation. The residual vasodilation after L-NAME was eliminated with co-administration of iberiotoxin. Conclusions UI elicits dilation of the retinal arterioles mediated by NO release and BKCa channel activation.

A "classic" response to acute vasodilator testing (drop of10 mm Hg in mean pulmonary artery pressure [mPAP] to40 mm Hg) confers an excellent prognosis in patients with idiopathic pulmonary arterial hypertension (IPAH) and identifies candidates for treatment with calcium channel blockers (CCB). Little is known about vasodilator responsiveness (VR) in other types of PAH, or about outcomes in patients with a significant but "non-classic" decrease in mPAP. We hypothesized that VR occurs in non-idiopathic PAH and non-classic VR portends a better prognosis than no VR in PAH.Acute VR testing with nitric oxide was performed on 155 consecutive patients referred for PH evaluation. Non-classic response was defined as decrease in mPAP10 mm Hg to40 mm Hg with preserved cardiac output. Demographics and functional status were assessed at baseline and the first clinic visit after VR testing, and survival was followed over time.Twenty patients (13%) displayed classic VR. Among classic responders, 12 (60%) had IPAH and 8 (40%) had connective tissue disease-associated PAH (CTD-PAH); however, only responders with IPAH had improved survival compared with non-responders (p = 0.02). Thirteen patients (8%) had a non-classic VR. Non-classic response was not associated with improved survival compared with non-responders (p = 0.86). Acute change in mPAP or pulmonary vascular resistance in the entire cohort did not predict survival.Classic acute VR occurs in CTD-PAH as well as IPAH; however, only IPAH patients have improved outcomes. A significant but non-classic VR is not associated with improved survival.

Nuclear factor erythyroid factor 2 (Nrf2) transcribes genes in cultured endothelial cells that reduce reactive oxygen species (ROS) and generate nitric oxide (NO) or metabolize asymmetric dimethylarginine (ADMA), which inhibits NO synthase (NOS). Therefore, we undertook a functional study to test the hypothesis that activation of Nrf2 by tert-butylhydroquinone (tBHQ) preserves microvascular endothelial function during oxidative stress. Wild-type CB57BL/6 (wt), Nrf2 wt (+/+), or knockout (−/−) mice received vehicle (Veh) or tBHQ (0.1%; activator of Nrf2) during 14-day infusions of ANG II (to induce oxidative stress) or sham. MAP was recorded by telemetry. Mesenteric resistance arterioles were studied on isometric myographs and vascular NO and ROS by fluorescence microscopy. ANG II increased the mean arterial pressure (112 ± 5 vs. 145 ± 5 mmHg; P < 0.01) and excretion of 8-isoprostane F2α (2.8 ± 0.3 vs. 3.8 ± 0.3 ng/mg creatinine; P < 0.05) at 12–14 days. However, 12 days of ANG II reduced endothelium-derived relaxation (27 ± 5 vs. 17 ± 3%; P < 0.01) and NO (0.38 ± 0.07 vs. 0.18 ± 0.03 units; P < 0.01) but increased microvascular remodeling, endothelium-derived contractions (7.5 ± 0.5 vs. 13.0 ± 1.7%; P < 0.01), superoxide (0.09 ± 0.03 vs. 0.29 ± 0.08 units; P < 0.05), and contractions to U-46,619 (87 ± 6 vs. 118 ± 3%; P < 0.05), and endothelin-1(89 ± 4 vs. 123 ± 12%; P < 0.05). tBHQ prevented all of these effects of ANG II at 12–14 days in Nrf2+/+ mice but not in Nrf2−/− mice. In conclusion, tBHQ activates Nrf2 to prevent microvascular endothelial dysfunction, remodeling, and contractility, and moderate ADMA and hypertension at 12–14 days of ANG II infusion, thereby preserving endothelial function and preventing hypertension.

Treatment of co-morbidities, including bronchial asthma (BA) and coronary heart disease (CHD), is a relevant issue of modern therapy. The aim of the research is to study the impact of long-term intake of pioglitazone on the development of inflammation and ED in patients with BA concurrent with CHD.The clinical study involved 50 people aged 40-75 who suffered from asthma concurrent with CHD. On the first day of the study, blood samples were collected and clinical examinations were performed, after which patients were randomized and divided into the control group who continued to receive only the standard therapy, and the study group, who received pioglitazone (Pioglar, Ranbaxy, India) 15 mg once a day along with comprehensive therapy. Re-examination was carried out in 6 months.It has been found that inclusion of pioglitazone in the course of standard therapy in patients with asthma concurrent with coronary heart within 6 months is a more efficient scheme than the course of standard therapies. According to the data obtained from the patients, there was a significant decrease in respiratory rate (p0.01), levels of systolic blood pressure (p0.001) and diastolic blood pressure (p0.001). Administering pioglitazone contributed to the improvement of respiratory function and airflow obstruction, increased FEV1 performance (p0.01) and Tiffeneau index (p0.05). In patients of the study group, intake of pioglitazone helped to reduce angina. Intake of pioglitazone showed a significant decrease in the frequency of angina pectoris FC II (p0.05) and a significant increase in the frequency of angina FC I (p0.05), increase in the rate of threshold load power (p0.05). In assessing endothelium-dependent vasodilation of the brachial artery, it has been noted that intake of pioglitazone by patients with asthma concurrent with coronary heart disease resulted in a statistically significant increase in the diameter of the brachial artery by an average of 4% (p0.0001), the maximum blood flow velocity (TAMX) by an average of 40 % (p0.0001), Δ% diameter increase in the brachial artery (p0.0001), and achieved positive indicators of RI (p0.0001). In assessing endothelium-dependent vasodilation of brachial artery in patients treated with pioglitazone, there was a significant increase in the diameter of brachial artery on average by 5% (p0.0001) after taking nitroglycerin, an increase in ?% diameter of brachial artery (p0.0001) and RI (p0.0001). Inclusion of pioglitazone in the complex therapy for 6 months resulted in a significant decrease in the index of systemic inflammation hs-CRP (p0.0001) and adhesion marker sVCAM-1 (p0.0001), total cholesterol (p0.001), triglycerides (p0.001).Thus, these data demonstrate the anti-inflammatory and endothelium protective effects of pioglitazone against the background of standard therapy in patients with BA concurrent with CHD within 6 months, which may enhance the clinical efficacy in the treatment of these diseases.

Ethnopharmacological relevance Thymus linearis, Benth indigenous to Pakistan has been traditionally used for the treatment of various diseases including hypertension. Aim of the study Present study aims to investigate vasorelaxant effect of Thymus linearis and its underlying vasorelaxation mechanisms in porcine coronary artery rings. Materials and methods Aqueous-methanolic extract of aerial parts of Thymus linearis was prepared by maceration process and then bio-guided fractionation was carried out using different solvents. The effects of extract and subsequent fractions were assessed on coronary artery rings with intact and denuded endothelium. The mechanisms of vasorelaxant effect were investigated using different pharmacological tools. The in-vitro inhibitory effects of the test fractions were also assessed on purified phophodiestrases using radioenzymatic assay. Phytochemical studies were carried out using GCMS. Results The aqueous-methanolic extract elicited similar relaxations in coronary artery rings with and without endothelium in dose dependent fashion and removal of endothelium did not alter this response. Further, n-butanolic fraction of Thymus liniaris (TLB) was found to be the most potent among other derived fractions. TLB did not alter the relaxation produced by endothelium dependent vasodilators in rings with intact endothelium. However, TLB significantly potentiated the relaxation elicited by cyclic AMP and cyclic GMP elevating drugs but not those to soluble guanylyl cyclase activators (YC-1 and BAY 41–2272) and K+ channel openers (levcromakalim and 1-EBIO). Pretreatment with TLB inhibited in a concentration-dependent manner contractions to KCl, CaCl2 and U46619 in coronary artery rings without endothelium. Further, TLB was found to non-selectively inhibit the PDE activity in concentration manner. Conclusion n-Butanolic fraction of Thymus linearis possesses endothelium independent vasorelaxant effects in coronary artery by direct acting on the smooth muscles. These effects involve the elevation of the cyclic AMP and cyclic GMP possibly through the inhibition of various PDEs. GCMS analysis revel presence of thymole and carvacrol as major constituents. Furthermore, these investigations also support the folklore use of Thymus linearis in hypertension.

BACKGROUND: Hypoxia induced relaxation of larger retinal arterioles has been shown to be mediated by nitric oxide (NO) and cyclo-oxygenase (COX) products both in vivo and in vitro. However, the involvement of smaller retinal vessels in the response is unknown. Therefore, the purpose of the present study was to investigate the effect of blocking the synthesis of NO and COX on hypoxia induced changes in the diameter of smaller porcine retinal vessels at different branching level.METHODS: Porcine hemiretinas were mounted in a tissue chamber and were constricted with the prostaglandin agonist U46619. Changes in the diameter of arterioles, pre-capillary arterioles and capillaries were studied during hypoxia, in the presence of the COX inhibitor ibuprofen and the NO synthase inhibitor L-NAME.RESULTS: In the presence of L-NAME hypoxia induced dilatation was significantly smaller in arterioles and capillaries than in precapillary arterioles (p < 0.04), whereas in the presence of ibuprofen the dilatation was significantly smaller in capillaries and pre-capillary arterioles than in arterioles (p < 0.04).CONCLUSIONS: The mechanisms underlying hypoxia induced dilatation differ among smaller porcine retinal vessels with different caliber ex vivo. This may reflect differences in the responses of retinal vessels to changes in metabolism, and may point to possible targets for pharmacological intervention on the diameter of retinal vessels with different caliber in vivo.

Thirty years ago, Robert F. Furchgott concluded that nitric oxide, a compound traditionally known to be a toxic component of fuel exhaust, is in fact released from the endothelium, and in a paracrine fashion, induces relaxation of underlying vascular smooth muscle resulting in vasodilation. This discovery has helped pave the way for a more thorough understanding of vascular intercellular and intracellular communication that supports the process of regulating regional perfusion to match the local tissue oxygen demand. Vasoregulation is controlled not only by endothelial release of a diverse class of vasoactive compounds such as nitric oxide, arachidonic acid metabolites, and reactive oxygen species, but also by physical forces on the vascular wall and through electrotonic conduction through gap junctions. Although the endothelium is a critical source of vasoactive compounds, paracrine mediators can also be released from surrounding parenchyma such as perivascular fat, myocardium, and cells in the arterial adventitia to exert either local or remote vasomotor effects. The focus of this review will highlight the various means by which intercellular communication contributes to mechanisms of vasodilation. Paracrine signaling and parenchymal influences will be reviewed as well as regional vessel communication through gap junctions, connexons, and myoendothelial feedback. More recent modes of communication such as vesicular and microRNA signaling will also be discussed.

Background: Resistance exercise (RE) has been recommended for patients with cardiovascular diseases. Recently, a few studies have demonstrated that the intensity of a single bout of RE has an effect on endothelial adaptations to exercise. However, there is no data about the effects of different volumes of RE on endothelium function. Objective: The aim of the study was to evaluate the effects of different volumes of RE in a single bout on endothelium-dependent vasodilatation and nitric oxide (NO) synthesis in the mesenteric artery of healthy animals. Methods: Male Wistar rats were divided into three groups: Control (Ct); low-volume RE (LV, 5 sets x 10 repetitions) and high-volume RE (HV, 15 sets x 10 repetitions). The established intensity was 70% of the maximal repetition test. After the exercise protocol, rings of mesenteric artery were used for assessment of vascular reactivity, and other mesenteric arteries were prepared for detection of measure NO production by DAF-FM fluorescence. Insulin responsiveness on NO synthesis was evaluated by stimulating the vascular rings with insulin (10 nM). Results: The maximal relaxation response to insulin increased in the HV group only as compared with the Ct group. Moreover, the inhibition of nitric oxide synthesis (L-NAME) completely abolished the insulin-induced vasorelaxation in exercised rats. NO production showed a volume-dependent increase in the endothelial and smooth muscle layer. In endothelial layer, only Ct and LV groups showed a significant increase in NO synthesis when compared to their respective group under basal condition. On the other hand, in smooth muscle layer, NO fluorescence increased in all groups when compared to their respective group under basal condition. Conclusions: Our results suggest that a single bout of RE promotes vascular endothelium changes in a volume-dependent manner. The 15 sets x 10 repetitions exercise plan induced the greatest levels of NO synthesis. Resumo Fundamentos: O exercício resistido (ER) tem sido recomendado para pacientes com doenças cardiovasculares. Recentemente, alguns estudos demonstraram que a intensidade de uma sessão de ER exerce um efeito sobre a disfunção endotelial. No entanto, não há dados sobre os efeitos de diferentes volumes de ER sobre a função endotelial. Objetivo: O objetivo deste estudo foi avaliar os efeitos de diferentes volumes de ER, realizados em uma única sessão, sobre a vasodilatação dependente do endotélio e síntese de óxido nítrico (NO) em artéria mesentérica de animais saudáveis. Métodos: Ratos Wistar machos foram divididos em três grupos: Controle (Ct); baixo volume (BV, 5 séries x 10 repetições) e alto volume de ER (AV, 15 séries x 10 repetições). Foi estabelecida a intensidade de 70% do teste de repetição máxima. Após o protocolo de exercício, anéis de artéria mesentérica foram utilizados na avaliação da reatividade vascular, e outras artérias mesentéricas foram preparadas para a detecção da produção de NO por fluorescência com para do DAF-FM. A resposta à insulina pela síntese de NO foi avaliada estimulando-se os anéis vasculares com insulina (10nM). Resultados: A resposta máxima do relaxamento induzido por insulina foi aumentada somente no grupo AV em comparação ao grupo Ct. Além disso, a inibição da síntese do NO (L-NAME), aboliu completamente o relaxamento vascular induzido por insulina em ratos exercitados. A produção de NO mostrou um aumento dependente do volume no endotélio e no músculo liso. No endotélio, apenas os grupos Ct e BV mostraram aumento significativo na síntese de NO quando comparado aos seus respectivos grupos sob condição basal. No entanto, no músculo liso, a fluorescência foi aumentada em todos os grupos quando comparados aos seus respectivos grupos sob a condição basal. Conclusões: Nossos resultados sugerem que uma única sessão de ER foi capaz de promover adaptações no endotélio vascular. Além disso, nós observamos que este efeito é volume-dependente e o volume de 15 séries x10 repetições induziu o maior aumento na síntese de NO.

The paper is devoted to characteristics of vascular and cardiac remodeling in patients with primary and recurrent myocardial infarction (MI). Data on multifocal atheroslerotic involvement of vessels in these patients associated with development of multivascular involvement of coronary arteries are presented. Emphasis is made on remodeling of vessels and the heart, parameters of vasodilation. We have elucidated frequency of vascular vasoconstrictory reactions in acute stage of MI and relationship between vascular and myocardial remodeling. Special consideration is given to possibility of correction of vascular vasoconstrictory reaction with indapamide. We have corroborated its administration starting from first days of treatment and demonstrated its effect during use for 3 months. We have established possibility of normalization of endothelium dependent vasodilation in most patients with primary MI. Expedience of the use of indapamide for prevention of development of chronic heart failure is stressed.

Studies about the effects of inhaled nitric oxide (iNO) on bleeding time and platelet aggregation in newborns are limited in number and have inconclusive results. Thromboelastogram (TEG) shows the combined effects of coagulation factors and platelet functions. In this preliminary study, we aimed to evaluate the effects of iNO on coagulation using TEG in newborns with persistent pulmonary hypertension (PPH). TEG assays were performed in 10 term infants receiving iNO treatment for PPH and 32 healthy term infants. Samples of the iNO group were collected before and during iNO. Clot reaction time (R), clot kinetics (K), maximum amplitude (MA), and alpha angle were obtained from the TEG tracing. TEG-R values were statistically higher during iNO treatment (7.75 ± 3.34) when compared to the values before iNO (4.83 ± 1.38) and the healthy controls (3.75 ± 0.98). The alpha angle was lower in iNO treated infants at both periods (before iNO, 55.33 ± 8.58; during iNO, 42.90 ± 18.34) compared to the control group (64.95 ± 6.88). MA values before iNO treatment were the lowest (44.43 ± 14.09) and improved with the iNO treatment (48.40 ± 9.49) despite still being lower compared to the controls (53.67 ± 5.56). Conclusion: Both PPH and iNO may negatively effect in vitro coagulation tests. Therefore, newborns with PPH requiring iNO treatment should be closely monitored for coagulation problems.

Speckle tracking echocardiography-derived myocardial strain has useful clinical applications in adults with pulmonary hypertension (PH) as well as preterm infants with chronic lung disease. It is considered more sensitive compared to conventional indices. This report presents a 3-month-old infant with PH and poor right ventricular function who was treated with inhaled nitric oxide. Myocardial strain was noted to be impaired with paradoxical segmental strain. Impairment in strain improved after inhaled nitric therapy. Strain analysis can help improve understanding of cardiac adaptation in critical clinical situations.

Ischemia-reperfusion injury forms the basis of tissue damage and cellular apoptosis in many pathologic and traumatic processes. The tissue damage follows a natural progression of cellular and metabolic events initiated by an ischemic episode. Ischemia causes intracellular/extracellular changes principally resulting in increased intracellular calcium, pH changes, and adenosine triphosphate depletion that end in cell death if the process is not interrupted. This interruption takes the form of reperfusion, characterized by a "flushing" of tissues with toxic metabolites, principally reactive oxygen species. The immediate effect is mitochondrial pore permeability, complement activation, cytochrome release, cytokine activation, inflammation, edema, neutrophil platelet adhesion, capillary plugging, and thrombosis. This sets the stage for the long recognized "no-reflow" phenomenon and progressive tissue death. Current recognition of cellular "cross-talk" and molecular events have introduced new logical strategies to sequentially combat the events occurring in relation to ischemia-reperfusion injury. These include mechanical preconditioning and pharmacological preconditioning and postconditioning strategies. It is likely that success in reversing or limiting tissue damage will be found in a sequential multitargeted approach using a combination of these strategies-clinical trials in this regard are sorely needed.

Selective cyclooxygenase 2 (COX2) inhibitors (COXIBs) are effective anti-inflammatory and analgesic drugs with improved gastrointestinal (GI) safety compared to nonselective nonsteroidal anti-inflammatory drugs known as traditional (tNSAIDs). However, their use is associated with a cardiovascular (CV) hazard (i.e. increased incidence of thrombotic events and hypertension) due to the inhibition of COX2-dependent vascular prostacyclin. Aiming to design COX2-selective inhibitors with improved CV safety, new NO-releasing COXIBs (NO-COXIBs) have been developed. In these hybrid drugs, the NO-mediated CV effects are expected to compensate for the COXIB-mediated inhibition of prostacyclin. This study evaluates the potential CV beneficial effects of VA694, a promising NO-COXIB, the anti-inflammatory effects of which have been previously characterized in several in vitro and in vivo experimental models. When incubated in hepatic homogenate, VA694 acted as a slow NO-donor. Moreover, it caused NO-mediated relaxant effects in the vascular smooth muscle. The chronic oral administration of VA694 to young spontaneously hypertensive rats (SHRs) significantly slowed down the age-related development of hypertension and was associated with increased plasma levels of nitrates, stable end-metabolites of NO. Furthermore, a significant improvement of coronary flow and a significant reduction of endothelial dysfunction were observed in SHRs submitted to chronic administration of VA694. In conclusion, VA694 is a promising COX2-inhibiting hybrid drug, showing NO releasing properties which may mitigate the CV deleterious effects associated with the COX2-inhibition.

Adipose tissue can be considered as a huge gland producing paracrine and endocrine hormones, the adipo(cyto)kines. There is growing evidence that these adipo(cyto)kines may link obesity to cardiovascular diseases. The excessive adipocyte hypertrophy in obesity induces hypoxia in adipose tissue. This leads to adiposopathy, the process that converts "healthy" adipose tissue to "sick" adipose tissue. This is accompanied by a change in profile of adipo(cyto)kines released, with less production of the "healthy" adipo(cyto)kines such as adiponectin and omentin and more release of the "unhealthy" adipo(cyto)kines, ultimately leading to the development of cardiovascular diseases. The present review provides a concise and general overview of the actual concepts of the role of adipo(cyto)kines in endothelial dysfunction, hypertension, atherosclerosis and heart diseases. The knowledge of these concepts may lead to new tools to improve health in the next generations.

Exercise training ameliorates age-related impairments in endothelium-dependent vasodilation in skeletal muscle arterioles. Additionally, exercise training is associated with increased superoxide production. The purpose of this study was to determine the role of superoxide and superoxide-derived reactive oxygen species (ROS) signaling in mediating endothelium-dependent vasodilation of soleus muscle resistance arterioles from young and old, sedentary and exercise-trained rats. Young (3 mo) and old (22 mo) male rats were either exercise trained or remained sedentary for 10 wk. To determine the impact of ROS signaling on endothelium-dependent vasodilation, responses to acetylcholine were studied under control conditions and during the scavenging of superoxide and/or hydrogen peroxide. To determine the impact of NADPH oxidase-derived ROS, endothelium-dependent vasodilation was determined following NADPH oxidase inhibition. Reactivity to superoxide and hydrogen peroxide was also determined. Tempol, a scavenger of superoxide, and inhibitors of NADPH oxidase reduced endothelium-dependent vasodilation in all groups. Similarly, treatment with catalase and simultaneous treatment with tempol and catalase reduced endothelium-dependent vasodilation in all groups. Decomposition of peroxynitrite also reduced endothelium-dependent vasodilation. Aging had no effect on arteriolar protein content of SOD-1, catalase, or glutathione peroxidase-1; however, exercise training increased protein content of SOD-1 in young and old rats, catalase in young rats, and glutathione peroxidase-1 in old rats. These data indicate that ROS signaling is necessary for endothelium-dependent vasodilation in soleus muscle arterioles, and that exercise training-induced enhancement of endothelial function occurs, in part, through an increase in ROS signaling.

Fructus Alpiniae Zerumbet (FAZ) is an herb widely used to treat vascular disorders in Guizhou province, China, the essential oil has been identified as one of it vasodilation effect active components, and especial, the composition was significantly difference from the leaves. Vasodilation effects and mechanism of essential oil from FAZ (EOFAZ) were investigated. The EOFAZ showed significant vasodilation effect on endothelium-with rat thoracic aortic rings preincubated with norepinephrine (NE, 1.0μM) or KCl (60mM) in a concentration-dependent manner (1.14-72.96μg/ml). The non-selective nitric oxide synthase inhibitor l-NAME, as well as the soluble guanylate cyclase inhibitor MB, attenuated the relaxation of EOFAZ in endothelium-intact rat thoracic aortic rings. However, there were not significantly affected the vasodilation effects pretreated with cyclooxygenase inhibition by indomethacin (Indo) or β-noradrenergic inhibition by propranolol (Prop). The present results first demonstrated that vasodilation effect of EOFAZ depending upon the endothelium and concentration, and the mechanism involvement of NOS-cGMP system. In contrast, prostacyclin and β-adrenoceptor may not be associated with EOFAZ-induced vasorelaxation.

The retinal circulation is regulated by different local factors and might include the retinal relaxing factor (RRF). This factor is found to be continuously released by the retina and relaxes smooth muscle cells. This review describes the current knowledge about the RRF. Despite many research efforts, the cellular source, identity, mechanism, and physiological role of the RRF remain largely unknown. Thus far, it seems that the RRF is a hydrophilic, thermostable, diffusible chemical messenger, which characteristics do not correspond with most well-known endogenous vasorelaxants. The RRF-induced relaxation seems to rely on activation of the inward rectifier K+ channels and the Rho kinase Ca2+ sensitization mechanism. Voltage-dependent K+ channels and plasma membrane Ca2+-ATPase might also be involved, whereas the involvement of cyclooxygenase is still a point of discussion. Furthermore, it appears that the RRF is involved in other relaxation pathways, namely those of hypoxia, adenosine, and adenosine triphosphate, hydrogen sulfide, c-aminobutyric acid, and dorzolamide.

Summary Background Recent epidemiological evidence indicates an association between cardiovascular diseases and pulmonary fibrosis. The vascular endothelium acts to maintain vascular homeostasis through multiple mechanisms and impaired endothelial function can contribute to the development, progression and clinical expression of atherosclerosis. Methods We consecutively recruited 39 newly-diagnosed chronic interstitial pneumonitis/fibrosis patients without any specific etiology. We assessed endothelium-dependent vasodilator response of patients using digital pulse amplitude tonometry and compared the reactive hyperemia index (RHI) with age-, sex- and body mass index-matched control subjects ( n = 30). We further investigated the relationships between RHI and clinical characteristics, laboratory cardiovascular risk factors, disease-related factors and circulating levels of inflammatory biomarkers. Results RHI was significantly lower in patients with chronic interstitial pneumonitis/fibrosis than in control subjects ( p = 0.02). While circulating levels of total cholesterol, triglycerides, HbA1c and fasting glucose did not differ significantly between groups, patients with chronic interstitial pneumonitis/fibrosis had significantly lower high density lipoprotein levels and higher low density lipoprotein levels as compared with control subjects. Regarding disease-related factors, RHI was significantly associated with the diffusing capacity for carbon monoxide, alveolar-arterial oxygen pressure difference, 6-min walk distance and end-exercise oxygen saturation. Additionally, circulating levels of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were inversely correlated with RHI. Conclusions We confirmed a possible link between pulmonary fibrosis and cardiovascular disease by demonstrating an impairment of endothelium-dependent vasodilator response, which was significantly associated with the severity of pulmonary fibrosis and circulating levels of adhesion molecules.

Background Exposure of red blood cells to oxidants increases production of methemoglobin (MHb) resulting in impaired oxygen delivery to tissues. There are no reliable estimates of methemoglobinemia in low resource clinical settings. Our objectives were to: i) evaluate risk factors for methemoglobinemia in Ugandan children hospitalized with fever (study 1); and ii) investigate MHb responses in critically ill Ugandan children with severe malaria treated with inhaled nitric oxide (iNO), an oxidant that induces MHb in a dose-dependent manner (study 2). Methods Two prospective studies were conducted at Jinja Regional Referral Hospital in Uganda between 2011 and 2013. Study 1, a prospective cohort study of children admitted to hospital with fever (fever cohort, n = 2089 children 2 months to 5 years). Study 2, a randomized double-blind placebo-controlled parallel arm trial of room air placebo vs. 80 ppm iNO as an adjunctive therapy for children with severe malaria (RCT, n = 180 children 1–10 years receiving intravenous artesunate and 72 h of study gas). The primary outcomes were: i) masimo pulse co-oximetry elevated MHb levels at admission (>2 %, fever cohort); ii) four hourly MHb levels in the RCT. Results In the fever cohort, 34 % of children admitted with fever had elevated MHb at admission. Children with a history of vomiting, delayed capillary refill, elevated lactate, severe anemia, malaria, or hemoglobinopathies had increased odds of methemoglobinemia (p 10 % occurred in 5.7 % of children receiving iNO. There were no differences in rates of study gas discontinuation between trial arms. Conclusions Hospitalized children with evidence of impaired oxygen delivery, metabolic acidosis, anemia, or malaria were at risk of methemoglobinemia. However, we demonstrated high-dose iNO could be safely administered to critically ill children with severe malaria with appropriate MHb monitoring. Trial registration ClinicalTrials.gov Identifier: NCT01255215 (Date registered: December 5, 2010).

The gasotransmitter nitric oxide was classified as the first endothelium-derived relaxant factor, and opened a new era in cardiovascular research. Another small gas, sulfur dioxide (SO₂), can also be generated endogenously in mammals. Recent studies have shown that SO₂ may play important roles in the cardiovascular system. At low concentrations, the vasodilatory effect of SO₂ is endothelium-dependent. The vasodilation induced by an endothelium-derived relaxant factor is achieved by the opening of potassium channels, and hyperpolarization of the membranes of vascular smooth muscle cells. This feature is in accordance with that of SO₂. The vasodilatory effect of SO₂ is related to the opening of adenosine triphosphate-sensitive potassium channels and high-conductance calcium-activated potassium channels. The 3'-5'-cyclic guanosine monophosphate pathway and activation of nitric oxide synthase are also involved in the endothelium-derived relaxant factor effect of SO₂. The vasodilatory effect of gaseous SO₂ is much stronger than that of its derivatives (bisulfite and sulfite). It is suggested that SO₂ may be a candidate endothelium-derived relaxant factor, which could lead to a new era of research into cardiovascular disease in mammals.

Conventional tumor starving therapy by reducing its vessel density may be effective at early treatment but potentially contributes to tumor hypoxia, drug resistance and metastasis. A new strategy through enhancing tumor angiogenesis in combination with effective chemotherapeutic drugs, has shown successful tumor growth and spread inhibition. To achieve in situ release of angiogenic and antitumor drugs in tumor, we designed a precise ratiometric polymeric hybrid micelle system for co-delivering nitric oxide and paclitaxel. The hybrid micelles could accumulate in tumor via the long blood circulation and enhanced permeability and retention (EPR) effect, promote the drug accumulation and penetration in tumor by in situ increased vascular permeability, blood perfusion and vessel density, achieve the synergistic antitumor effect of nitric oxide and paclitaxel through modified tumor microenvironment, overcome multidrug resistance and inhibit metastasis. This study presents a combinational therapy against tumor progression and spread, which shows great potential in cancer therapy of the future.

Resistance training is one of the most common kind of exercise used nowadays. Long-term high-intensity resistance training are associated with deleterious effects on vascular adjustments. On the other hand, is unclear whether low-intensity resistance training (LI-RT) is able to induce systemic changes in vascular tone. Thus, we aimed to evaluate the effects of chronic LI-RT on endothelial nitric oxide (NO) bioavailability of mesenteric artery and cardiovascular autonomic modulation in healthy rats. Wistar animals were divided into two groups: exercised (Ex) and sedentary (SED) rats submitted to the resistance (40% of 1RM) or fictitious training for 8 weeks, respectively. After LI-RT, hemodynamic measurements and cardiovascular autonomic modulation by spectral analysis were evaluated. Vascular reactivity, NO production and protein expression of endothelial and neuronal nitric oxide synthase isoforms (eNOS and nNOS, respectively) were evaluated in mesenteric artery. In addition, cardiac superoxide anion production and ventricle morphological changes were also assessed. In vivo measurements revealed a reduction in mean arterial pressure and heart rate after 8 weeks of LI-RT. In vitro studies showed an increased acetylcholine (ACh)-induced vasorelaxation and greater NOS dependence in Ex than SED rats. Hence, decreased phenylephrine-induced vasoconstriction was found in Ex rats. Accordingly, LI-RT increased the NO bioavailability under basal and ACh stimulation conditions, associated with upregulation of eNOS and nNOS protein expression in mesenteric artery. Regarding autonomic control, LI-RT increased spontaneous baroreflex sensitivity, which was associated to reduction in both, cardiac and vascular sympathetic modulation. No changes in cardiac superoxide anion or left ventricle morphometric parameters after LI-RT were observed. In summary, these results suggest that RT promotes beneficial vascular adjustments favoring augmented endothelial NO bioavailability and reduction of sympathetic vascular modulation, without evidence of cardiac overload.

Background: Childhood acute lymphoblastic leukemia (ALL) survivors are at higher cardiovascular risk than the general population, which may result from anthracycline-related endothelial dysfunction (ED). However, a few studies indirectly show that ED may appear in ALL children before treatment begins. Hence, in this study we intended to verify the hypothesis that ED is part of the ALL phenotype.Patients/Methods: Twenty-eight ALL children and 14 healthy age-matched control children were recruited. The study group was examined at baseline, then at the 33rd and 78th day of treatment. At each step of the protocol endothelial vasodilative function was assessed by a laser Doppler flowmeter, which was followed by blood collecting for subsequent analyses.Results: Compared to controls, the study group at baseline was characterized by significantly lower endothelial vasodilative responsiveness, accompanied by elevated asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) concentrations, which were correlated with lactate dehydrogenase (LDH) and aspartate transaminase (AST). Initial ALL treatment restored endothelial function, which followed changes in ADMA and LDH concentrations.Discussion: This is the first demonstration that functionally assessed ED is present in ALL children at the diagnosis and results from elevated ADMA and parallel inflammatory ED.

The endothelium contributes to the maintenance of vasodilator tone by releasing nitric oxide (NO), prostacyclin (PGI2), and endothelium-derived hyperpolarizing factor (EDHF). In hypertension, endothelium-dependent relaxation is attenuated (a phenomenon referred to as endothelial dysfunction) and contributes to the increased peripheral resistance. However, which vasodilator among NO, PGI2, and EDHF is impaired in hypertension remains largely unknown. The present study was designed to study the exact contribution of NO, PGI2, and EDHF to vascular reactivity in conduit and resistance artery, under physiological and pathological conditions. The aorta and the second-order mesenteric artery from spontaneous hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were used to measure the vasorelaxation with myograph technology, in the presence or absence of different inhibitors. The results showed that the endothelium-dependent vasodilatation in the conduit artery was mediated mainly by NO, whereas the resistant artery by NO, PGI2, and EDHF together. In hypertension, both NO-mediated relaxation in the conduit artery and NO-, PGI2-, and EDHF-mediated dilation in the resistant artery were markedly impaired. Furthermore, the endothelium-dependent and the endothelium-independent vasorelaxation in conduit artery was attenuated more pronouncedly than that in the resistant artery from hypertensive rats, suggesting that the conduit artery is more vulnerable to hypertensive condition. In conclusion, vasodilators including NO, PGI2, and EDHF contribute distinctively to endothelium-dependent relaxation in conduit and resistance artery under physiological and pathological conditions.

Several studies suggest that diabetes affects male and female vascular beds differently. However, the mechanisms underlying the interaction of sex and diabetes remain to be investigated. This study investigates whether there are 1) sex differences in the development of abnormal vascular responses and 2) changes in the relative contributions of endothelium-derived relaxing factors in modulating vascular reactivity of mesenteric arteries taken from streptozotocin (STZ)-induced diabetic rats at early and intermediate stages of the disease (1 and 8 wk, respectively). We also investigated the mesenteric expression of the mRNAs for endothelial nitric oxide (NO) synthase (eNOS) and NADPH oxidase (Nox) in STZ-induced diabetes in both sexes. Vascular responses to acetylcholine (ACh) in mesenteric arterial rings precontracted with phenylephrine were measured before and after pretreatment with indomethacin (cyclooxygenase inhibitor), Nω-nitro-l-arginine methyl ester (NOS inhibitor), or barium chloride (Kir blocker) plus ouabain (Na+-K+-ATPase inhibitor). We demonstrated that ACh-induced relaxations were significantly impaired in mesenteric arteries from both male and female diabetic rats at 1 and 8 wk. However, at 8 wk the extent of impairment was significantly greater in diabetic females than diabetic males. Our data also showed that in females, the levels of eNOS, Nox2, and Nox4 mRNA expression and the relative importance of NO to the regulation of vascular reactivity were substantially enhanced, whereas the importance of endothelium-derived hyperpolarizing factor (EDHF) was significantly reduced at both 1 and 8 wk after the induction of diabetes. This study reveals the predisposition of female rat mesenteric arteries to vascular injury after the induction of diabetes may be due to a shift away from a putative EDHF, initially the major vasodilatory factor, toward a greater reliance on NO.

Nitric oxide (NO)-associated pulmonary edema is rarely reported in children; in adults, it is often associated with left-sided heart failure. We report a case series of children with NO-associated pulmonary edema, which was defined as new multilobar alveolar infiltrates and worsening hypoxemia within 24 h of initiation or escalation of NO and radiologic or clinical improvement after NO discontinuation. We identified six patients (0.4-4 years old) with ten episodes of NO-associated pulmonary edema. Diagnoses included atrioventricular canal defect with mitral valve disease (n = 2), pulmonary atresia and major aorta-pulmonary collateral arteries (n = 2), total anomalous pulmonary venous return (n = 1), and pulmonary veno-occlusive disease (n = 1). All patients had evidence of pulmonary venous hypertension, and two had mitral valve disease resulting in clinical evidence of left-sided heart failure. Pulmonary edema improved or resolved within 24 h of discontinuing NO. At cardiac catheterization, mean left atrial pressure was15 mmHg in three of three patients (none with mitral valve disease), whereas pulmonary artery occlusion pressure was15 mmHg in two of five patients. In conclusion, we describe six young children with NO-associated pulmonary edema and pulmonary venous hypertension. Only two of these children had left-sided heart failure: Left atrial pressure as well as pulmonary artery occlusion pressure may not be helpful in identifying children at risk for NO-associated pulmonary edema.

Classical physiology teaches that vagal post-ganglionic nerves modulate the heart via acetylcholine acting at muscarinic receptors, whilst it is accepted that vagus nerve stimulation (VNS) slows heart rate, atrioventricular conduction and decreases atrial contraction; there is continued controversy as to whether the vagus has any significant direct effect on ventricular performance. Despite this, there is a significant body of evidence from experimental and clinical studies, demonstrating that the vagus nerve has an anti-arrhythmic action, protecting against induced and spontaneously occurring ventricular arrhythmias. Over 100 years ago Einbrodt first demonstrated that direct cervical VNS significantly increased the threshold for experimentally induced ventricular fibrillation. A large body of evidence has subsequently been collected supporting the existence of an anti-arrhythmic effect of the vagus on the ventricle. The development of prognostic indicators of heart rate variability and baroreceptor reflex sensitivity--measures of parasympathetic tone and reflex activation respectively--and the more recent interest in chronic VNS therapy are a direct consequence of the earlier experimental studies. Despite this, mechanisms underlying the anti-arrhythmic actions of the vagus nerve have not been fully characterised and are not well understood. This review summarises historical and recently published data to highlight the importance of this powerful endogenous protective phenomenon.

The role of endothelial and neural factors as modulators of neurogenic- and noradrenaline-induced vasoconstriction was examined in healthy pig internal mammary artery (IMA). Tetrodotoxin-, guanethidine-sensitive electrical field stimulation (EFS)-, and noradrenaline-elicited contractions were significantly diminished by prazosin (n=8, P0.001) and less so by rauwolscine, indicating functional α₁- and α₂-adrenoceptor-mediated noradrenergic innervation of the IMA. Endothelium removal reduced neurogenic (n=8, P0.01) but augmented noradrenaline responses (n=8, P0.01), suggesting the release of two endothelium-dependent factors with opposite effects. In the presence of endothelium, neurogenic and exogenous noradrenaline vasoconstrictions were enhanced by L-NOArg (n=7, P0.05 and P0.01 respectively) and ODQ (n=7, both P0.05); in denuded arteries, nNOS inhibition with N(ω)-propyl-L-arginine increased neurogenic contraction (n=7, P0.05). Western blotting indicated the presence of neural and endothelial origin NO (n=6, P0.001). Tetraethylammonium (n=9, P0.001), iberiotoxin (n=7, P0.001) and 4-aminopyridine (n=8, P0.01) enhanced vasoconstrictions revealing a modulatory role of big conductance Ca²⁺-activated K⁺ (BK(Ca)) and voltage-dependent K⁺ (K(v)) channels in noradrenergic responses. Bosentan pretreatment (n=8, P0.05) suggested endothelin-1 as the inferred contractile neurogenic endothelial-dependent factor. Indomethacin-induced inhibition involved a muscular prostanoid (n=9, P0.05), functionally and immunologically localized, and derived from cyclooxygenase (COX)-1 and COX-2, as revealed by Western blots (n=5, P=0.1267). Thus, noradrenergic IMA contractions are controlled by contractile prostanoid activation and endothelin-1 release, and offset by BK(Ca) and K(v) channels and neural and endothelial NO. These results help clarify the mechanisms of vasospasm in IMA, as the preferred vessel for coronary bypass.

The perinatal transition from fetal to extrauterine life requires a dramatic change in the circulatory pattern as the organ of gas exchange switches from the placenta to the lungs. Pulmonary hypertension can occur during early newborn life, and present as early respiratory failure or as a complication of more chronic diseases, such as bronchopulmonary dysplasia. The most effective pharmacotherapeutic strategies for infants with persistent pulmonary hypertension of the newborn are directed at selective reduction of pulmonary vascular resistance. This article discusses currently available therapies for pulmonary hypertension, their biologic rationales, and evidence for their clinical effectiveness.

Surgical intervention for congenital heart disease (CHD) can be complicated by pulmonary hypertension (PH), which increases morbidity, mortality, and medical burden. Consequently, postoperative management of PH is an important clinical consideration to improve outcomes. Inhaled nitric oxide (iNO) is a widely accepted standard of care for PH and has been studied in the context of cardiac surgery for CHD. However, large randomized, double-blind, placebo-controlled, multicenter clinical trials in pediatric patients are limited. This review will provide an overview of the clinical studies in this setting and will discuss general treatment considerations to facilitate a better understanding of the clinical use of iNO for PH after pediatric cardiac surgery.

Background The aim of this study is to compare the effect of physical exercise program on the endothelial function of patients with metabolic syndrome and type 2 diabetes mellitus. Methods Patients were randomized for high intensity aerobic training (HI: 80% maximum heart rate, n = 10), low intensity aerobic training (LI: 55% of maximum heart rate, n = 10) and control ( n = 11). Before and after 6 weeks of training, subjects performed the maximal exercise test and a study of the endothelial function, through a high resolution ultrasound of the brachial artery, which was assessed after reactive hyperemia (endothelium dependent vasodilation) and nitrate administration (endothelium independent vasodilation). Results A total of 31 patients with metabolic syndrome and type 2 diabetes mellitus were studied, with mean age of 58 ± 6 years, The percentage diameter difference of the vessel after hyperemia was significantly higher for the high intensity group (HI before 2.52 ± 2.85% and after 31.81 ± 12.21%; LI before 3.23 ± 3.52% and after 20.61 ± 7.76%; controls before 3.56 ± 2.33% and after 2.43 ± 2.14%; p Conclusions High intensity aerobic training improved the functional capability and endothelium dependent vasodilator response, but it does not improve the endothelium independent vasodilation in patients with metabolic syndrome and type 2 diabetes mellitus.

The present study investigated whether histamine was taken up by perivascular adrenergic nerves and released by periarterial nerve stimulation (PNS) to induce vascular responses. In rat mesenteric vascular beds treated with capsaicin to eliminate calcitonin gene–related peptide (CGRP)ergic vasodilation and with active tone, PNS (1 – 4 Hz) induced only adrenergic nerve–mediated vasoconstriction. Histamine treatment for 20 min induced PNS-induced vasoconstriction followed by vasodilation without affecting CGRP-induced vasodilation. Chlorpheniramine, guanethidine, combination of histamine and desipramine, and endothelium-removal abolished PNS-induced vasodilation in histamine-treated preparations. These results suggest that histamine taken up by and released from adrenergic nerves by PNS causes endothelium-dependent vasodilation in rat mesenteric arteries. Keywords:: histamine, perivascular adrenergic nerve, rat mesenteric artery

Within schizophrenia cardiovascular disease (CVD) is highly prevalent secondary to atypical antipsychotic (AAP) use. Thorough assessments of diet, lifestyle, and endothelial functioning have not been done in this population. Omega 3 Fatty Acids (N-3 FAs) have garnered attention in relation to psychopathology as well as cardioprotection. This study examined the status of endothelial function within the schizophrenia population and determined pharmacogenetic, medication, dietary, and lifestyle factors associated with this functioning.Schizophrenia subjects were screened for the metabolic syndrome along with physical activity, smoking, and variants related to folate pharmacogenetics in this cross-sectional analysis. Arteriole endothelial-dependent vasodilatation was measured using non-invasive peripheral arterial tonometry (RH-PAT, EndoPAT2000). A 24h dietary food recall was used to construct intake profiles using the Nutrition Data Systems for Research software (NDSR). We examined associations between AAP use and RH-PAT values, and the influence of N-3 FA dietary intake on this measure. Preliminary data are reported in 83 subjects with a mean age (±s.d.) of 45.89 (±11.49), 64% were Caucasian (n=53), 64% were male (n=53), and 77% were receiving AAP treatment (n=63).A significant positive relationship was found between RH-PAT values and N-3 FA intake (F=17.7(1,16), p=0.0007) in subjects not receiving AAPs. This relationship was lost in those treated with AAPs (F=0.25(1,43), p0.6). Regression analysis confirmed the interaction effect of AAP treatment on the relationship between RH-PAT and N-3 FAs (p=0.0105). Endothelial dysfunction was also related to folate pharmacogenetic variants.AAPs may counteract some vascular health benefits of a diet high in N-3 FAs. AAP use may necessitate a higher N-3 FA dose to regain these effects, but additional research is necessary to strengthen the preliminary findings. Pharmacogenetic variants related to folate and homocysteine metabolism may also increase endothelial dysfunction risk.

Retinal relaxing factor (RRF) is suggested to be released from the retina and to contribute in the maintenance of retinal arterial tone. Herein, we aimed to clarify the effects of retinal tissue in isolated bovine retinal arteries in comparison with choroidal tissue and to evaluate the possible role of endothelium and potassium channels. In parallel, the effects of palmitic acid methyl ester (PAME), a putative vasodilator proposed to be released from the retina, was also examined. A piece of bovine retinal or choroidal tissue was placed within a close proximity on top of retinal arteries mounted in a wire myograph and precontracted with noradrenaline, prostaglandin F 2α , endothelin-1, thromboxane A 2 mimetic, U46619 or potassium (K + ). To elucidate possible mechanisms in the effects of retinal tissue, retinal arteries were either deendothelized or incubated with inhibitors of endothelial vasodilators, i.e. nitric oxide (NO) and prostaglandins, or K + channels. Unlike the choroid, retinal tissue produced rapid, biphasic and complete relaxations in isolated bovine retinal arteries precontracted with various spasmogens acting on distinct receptors. Endothelium removal or preincubation of retinal arteries with inhibitors of NO synthase; L-NOARG (10 − 4 M), guanylate cyclase; ODQ (10 − 5 M) and cyclooxygenase; indomethacin (10 − 5 M), did not cause a significant difference in the relaxation profile. Additionally, retinal relaxations remained unchanged in the presence of respective inhibitors of ATP-sensitive (K ATP ) (glibenclamide, 10 − 5 M), voltage-dependent (K V ) (4-aminopyridine, 2 × 10 − 3 M), and calcium-activated (K Ca ) (tetraethylammonium 10 mM; charybdotoxin, 10 − 7 M; and apamin, 5 × 10 − 7 M) K + channels. Thus, our results provide novel evidence regarding the biphasic relaxing profile of RRF in the retinal artery which was unrelated to endothelium and K + channels (K ATP , K V and K Ca ). Interestingly, PAME (10 − 14 –10 − 5 M) did not provoke a relaxation in bovine retinal artery suggesting no association with RRF.

James Black believed that analysis of biological assays provides insights into the operation of physiological control systems. In this paper, we illustrate this point in three ‘cardiovascular' assays. The first determined the half-life (t½) of ‘endothelium-derived relaxing factor' (EDRF), using bradykinin to release EDRF, which produced concentration-related relaxations of a precontracted artery. With the introduction of time delays between the source of EDRF and the assay artery, there were rightward shifts in dose-response curves, which provided the basis of calculating t½. The second assay determined the roles of noradrenaline reuptake and prejunctional α 2 -adrenoceptor activity on transmitter concentration at sympathetic synapses with atria and resistance vessels. In the former, the reuptake role was paramount, whilst prejunctional receptor activity was dominant at vascular synapses, owing to anatomical differences. The third assay provided in vivo estimates of the enhancement of the total peripheral resistance responses to constrictor and dilator stimuli owing to the structural changes in hypertension. Major nonlinearities in the dose-response curve obscured this enhancement. Their effect was avoided by deriving extended dose-response curves from combined constrictor and dilator data, permitting calculation of the enhancement over the range between the nonlinearities.

Pulmonary hypertension represents an important cause of morbidity and mortality in patients with mitral stenosis who undergo cardiac surgery, especially in the postoperative period. The aim of this study was to test the hypothesis that inhaled nitric oxide (iNO) would improve the hemodynamic effects and short-term clinical outcomes of patients with mitral stenosis and severe pulmonary hypertension who undergo cardiac surgery in a randomized, controlled study. Twenty-nine patients (4 men, 25 women; mean age 46 ± 2 years) were randomly allocated to receive iNO (n = 14) or oxygen (n = 15) for 48 hours immediately after surgery. Hemodynamic data, the use of vasoactive drugs, duration of stay, and short-term complications were assessed. No differences in baseline characteristics were observed between the groups. After 24 and 48 hours, patients receiving iNO had a significantly greater increase in cardiac index compared to patients receiving oxygen (p

Objective: To examine the ability of vasodilator response to predict survival in a diverse cohort of patients with pulmonary hypertension (PH). Patients & Methods: A total of 214 consecutive treatment-naive patients referred for invasive PH evaluation were enrolled between November 1998 and December 2008. Vasoreactivity was assessed during inhalation of 40 parts per million nitric oxide (iNO) and vasodilator responders were defined as those participants who achieved a mean pulmonary artery pressure (PAP) of # 40 mm Hg and a drop in mean PAP $ the median for the cohort (13%). Kaplan-Meier analysis and Cox proportional hazards modeling were used to identify predictors of survival. Results: There were 51 deaths (25.9%) over a mean follow-up period of 2.3 years. Kaplan-Meier analysis demonstrated that vasodilator responders had significantly improved survival (P ! .01). Vasodilator responders had improved survival regardless of whether or not they had idiopathic or nonidiopathic PH (P 5 .02, P ! .01) or whether or not they had Dana Point class 1 or non-Dana Point class 1 PH (P ! .01, P 5 .01). In multivariate modeling, advanced age, elevated right atrial pressure, elevated serum creatinine, and worsened functional class significantly predicted shorter survival (P 5 .01, P 5 .01, P 5 .01, P ! .01), whereas vasodilator response predicted improved survival (P 5 .01). Conclusions: Vasodilator responsiveness to iNO is an important method of risk stratifying PH patients, with results that apply regardless of clinical etiology. (J Cardiac Fail 2011;17:265e271)

SummaryDespite antibiotic therapy, infections with Neisseria meningitidis still demonstrate a high rate of morbidity and mortality even in developed countries. The fulminant septicaemic course, named Waterhouse-Friderichsen syndrome, with massive haemorrhage into the adrenal glands and widespread petechial bleeding suggest pathophysiological inhibition of platelet function. Our data show that N. meningitidis produces the important physiological platelet inhibitor and cardiovascular signalling molecule nitric oxide (NO), also known as endothelium-derived relaxing factor (EDRF). N. meningitidis-derived NO inhibited ADPinduced platelet aggregation through the activation of soluble guanylyl cyclase (sGC) followed by an increase in platelet cyclic nucleotide levels and subsequent activation of platelet cGMP- and cAMP- depend- ent protein kinases (PKG and PKA). Furthermore, direct measurement of horseradish peroxidase (HRP) passage through a vascular endothelial cell monolayer revealed that N. meningitidis significantly increased endothelial monolayer permeability. Immunfluorescence analysis demonstrated NO dependent disturbances in the structure of endothelial adherens junctions after co-incubation with N. meningitidis. In contrast to platelet inhibition, the NO effects on HBMEC were not mediated by cyclic nucleotides. Our study provides evidence that NO plays an essential role in the pathophysiology of septicaemic meningococcal infection.

Myoendothelial microdomain signaling via localized calcium-activated potassium channel (K(Ca)) and gap junction connexins (Cx) is critical for endothelium-dependent vasodilation in rat mesenteric artery. The present study determines the relative contribution of NO and gap junction-K(Ca) mediated microdomain signaling to endothelium-dependent vasodilation in human mesenteric artery. The hypothesis tested was that such activity is due to NO and localized K(Ca) and Cx activity. In mesenteric arteries from intestinal surgery patients, endothelium-dependent vasodilation was characterized using pressure myography with pharmacological intervention. Vessel morphology was examined using immunohistochemical and ultrastructural techniques. In vessel segments at 80 mm Hg, the intermediate (I)K(Ca) blocker 1-[(2-chlorophenyl)diphenyl-methyl]-1H-pyrazole (TRAM-34; 1 μM) inhibited bradykinin (0.1 nM-3 μM)-induced vasodilation, whereas the small (S) K(Ca) blocker apamin (50 and 100 nM) had no effect. Direct IK(Ca) activation with 1-ethyl-2-benzimidazolinone (1-EBIO; 10-300 μM) induced vasodilation, whereas cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (1-30 μM), the SK(Ca) activator, failed to dilate arteries, whereas dilation induced by 1-EBIO (10-100 μM) was blocked by TRAM-34. Bradykinin-mediated vasodilation was attenuated by putative gap junction block with carbenoxolone (100 μM), with remaining dilation blocked by N-nitro l-arginine methyl ester (100 μM) and [1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (10 μM), NO synthase and soluble guanylate cyclase blockers, respectively. In human mesenteric artery, myoendothelial gap junction and IK(Ca) activity are consistent with Cx37 and IK(Ca) microdomain expression and distribution. Data suggest that endothelium-dependent vasodilation is primarily mediated by NO, IK(Ca), and gap junction Cx37 in this vessel. Myoendothelial microdomain signaling sites are present in human mesenteric artery and are likely to contribute to endothelium-dependent vasodilation via a mechanism that is conserved between species.

Hypertension contributes significantly to worldwide cardiovascular morbidity and mortality. Hypertension appears to have a complex association with endothelial dysfunction, a phenotypical alteration of the vascular endothelium that precedes the development of adverse cardiovascular events and portends future cardiovascular risk. This review concentrates on recent findings with respect to the mechanisms of hypertension-associated endothelial dysfunction, the interrelationship between these two entities, and the relationship of the efficacy of antihypertensive therapies to improvements in vascular homeostasis beyond blood pressure reduction. Current evidence suggests that hypertension and endothelial dysfunction are integrally related with respect to pathophysiologic mechanisms. Future studies will need to identify the key connections between hypertension and endothelial dysfunction to allow novel interventions to be designed and promulgated.

Evidence from our laboratory and others suggests a negative effect for cyclosporine A (CSA) on renovascular reactivity. This study investigated the role of peroxisome proliferator-activated receptor gamma (PPAR gamma)/nitric oxide synthase (NOS) signaling in the CSA-induced attenuation of endothelium-dependent vasodilations in phenylephrine-preconstricted perfused kidneys of rats. Bolus injection of carbachol (4 micromoL) reduced the renal perfusion pressure with a peak depressor effect observed at 2 minutes. CSA (5 microM) infusion significantly attenuated the vasodilatory action of carbachol. The specificity of this interaction was verified by the lack of effect of CSA on renal vasodilation caused by papaverine (50 nmol). The carbachol-induced renal vasodilations were also reduced after infusion of N-nitro-L-arginine methyl ester (L-NAME, NOS inhibitor, 100 microM) or 2-chloro-5-nitro-N-phenylbenzamide (GW9662, PPAR gamma antagonist, 1 microM). The attenuation of carbachol vasodilation by CSA was abolished in presence of L-arginine or L-NAME in contrast to no effect for GW9662. Pioglitazone (PPAR gamma agonist, 10 microM) abolished the CSA-induced attenuation of carbachol responses, an effect that was not manifest in presence of GW9662 or l-NAME. These findings suggest that PPAR gamma act tonically to facilitate renovascular dilatory response to endothelial muscarinic receptor activation. More importantly, NOS signaling downstream of PPAR gamma mediates, at least partly, the inhibitory effect of CSA on carbachol vasodilations.

It is widely accepted that vascular endothelium regulates vasoconstriction via release of endothelium-derived relaxing factors (EDRF). The mesenteric circulation, which is the largest vascular bed, influences regulation of systemic blood pressure. However, the role of EDRF in the modulation of vascular tone in peripheral mesenteric circulation has not been extensively studied. Therefore, our recent studies investigated the role of the vascular endothelium in the regulation of methoxamine (alpha(1)-adrenoceptor agonist)-induced vasoconstriction and their age-related changes in rat mesenteric vascular beds. In mesenteric vascular beds with intact endothelium isolated from 8 week-old rats, the initial maximum vasoconstriction induced by continuous perfusion of methoxamine was time-dependently decreased during 3 hour-perfusion. Neither nitric oxide synthase inhibitor nor cyclooxygenase inhibitor altered this time-dependent reduction of methoxamine-induced vasoconstriction. Endothelium removal, K(+)-channel inhibitors and gap junction inhibitor significantly inhibited the time-dependent reduction of methoxamine-induced vasoconstriction. In the preparations with intact endothelium from 16 week-old rats, the time-dependent reduction of methoxamine-induced vasoconstriction disappeared. Furthermore, endothelium removal and treatment with cyclooxygenase inhibitor, thromboxane A(2) receptor antagonist or superoxide dismutase mimetic significantly reduced the methoxamine-induced vasoconstriction in the preparations from 16 week-old rats. These findings suggest that vascular endothelium acts to depress methoxamine-induced vasoconstriction by releasing endothelium-derived hyperpolarizing factor (EDHF), and dysfunction in this endothelial modulation develops with ageing.

This study aims to investigate the role of shear stress in cellular remodeling and angiogenesis with relation to nitric oxide (NO). We observed a 2-fold increase in endothelial cell (EC) migration in relation to actin re-arrangements under 15 dyne/cm(2) shear stress. Blocking NO production inhibited the migration and ring formation of ECs by 6-fold and 5-fold, respectively under shear stress. eNOS-siRNA knockdown technique also ascertained a 3-fold reduction in shear stress mediated ring formation. In ovo artery ligation model with a half and complete flow block for 30 min showed a reduction of angiogenesis by 50% and 70%, respectively. External stimulation with NO donor showed a 2-fold recovery in angiogenesis under both half and complete flow block conditions. NO intensity clustering studies by using Diaminofluorescein diacetate (DAF-2DA) probed endothelial monolayer depicted pattern-changes in NO distribution and cluster formation of ECs under shear stress. Immunofluorescence and live cell studies revealed an altered sub-cellular localization pattern of eNOS and phospho-eNOS under shear stress. In conclusion, shear-induced angiogenesis is mediated by nitric oxide dependent EC migration.