Quinacrine increases endothelial nitric oxide release: role of superoxide anion

The effect of acute quinacrine treatment on agonist-induced nitric oxide (NO) release was investigated in cultured human endothelial cells using electrochemical monitoring of the in situ NO concentration. Quinacrine dose-dependently increased NO release with an apparent EC50 of 0.2 microM and a maximal effect at 1 microM. Quinacrine did not modify the dependence of NO release on extracellular L-arginine. Acceleration or deceleration of O2- dismutation, which altered NO release in control cells, did not modify it in quinacrine-treated cells. Quinacrine did not modify NO amperometric signal or reaction with O2- produced by xanthine oxidation. In the presence of quinacrine, agonist-induced NO release became Mg2+ -independent and could not be attributed to an inhibition of phospholipase A2 activity. Quinacrine made NO release insensitive to Cu2+ chelation. The present study demonstrates that acute treatment by low quinacrine concentrations increases endothelial NO release, possibly through an inhibition of O2- production.     

Molecular basis for arsenic-induced alteration in nitric oxide production and oxidative stress: implication of endothelial dysfunction

Accumulated epidemiological studies have suggested that prolonged exposure of humans to arsenic in drinking water is associated with vascular diseases. The exact mechanism of how this occurs currently unknown. Nitric oxide (NO), formed by endothelial NO synthase (eNOS), plays a crucial role in the vascular system. Decreased availability of biologically active NO in the endothelium is implicated in the pathophysiology of several vascular diseases and inhibition of eNOS by arsenic is one of the proposed mechanism s for arsenic-induced vascular diseases. In addition, during exposure to arsenic, overproduction of reactive oxygen species (ROS) can occur, resulting in oxidative stress, which is another major risk factor for vascular dysfunction. The molecular basis for decreased NO levels and increased oxidative stress during arsenic exposure is poorly understood. In this article, evidence for arsenic-mediated alteration in NO production and oxidative stress is reviewed. The results of a cross-sectional study in an endemic area of chronic arsenic poisoning and experimental animal studies to elucidate a potential mechanism for the impairment of NO formation and oxidative stress caused by prolonged exposure to arsenate in the drinking water are also reviewed.     

Interaction between superoxide anion and nitric oxide in the regulation of vascular endothelial function

1. Nitric oxide (NO)-mediated, endothelium-dependent vasodilator function in rat aortic smooth muscle was investigated in an in vitro model of endogenous vascular superoxide anion stress, generated by pretreatment with the Cu/Zn superoxide dismutase (SOD, EC 1.15.1.1) inhibitor, diethyldithiocarbamate (DETCA).
2. Contraction to noradrenaline (NA, 1 nM–1 μM) in endothelium-intact vessels was augmented after a 30 min pretreatment with DETCA (10 mM) followed by 30 min washout. This effect was abolished by N^G-nitro-L-arginine methyl ester (L-NAME, 0.3 mM) and removal of the endothelium and partially reversed by exogenous Cu/Zn SOD (200 u ml⁻¹).
3. Endothelium- and basal NO-dependent vasorelaxation to the phosphodiesterase (PDE) type V inhibitor ONO-1505 (4-[2-(2-hydroxyethoxy)ethylamino]-2-(1H-imidazol-1-yl)-6-methoxyquinazoline methanesulphonate) (0.1–10 μM) was inhibited after DETCA (10 mM) pretreatment. In addition, the ability of L-NAME (0.3 mM) to enhance established contractile tone was effectively absent.
4. In contrast, DETCA pretreatment did not significantly affect vasorelaxation to acetylcholine (ACh, 1 nM–3 μM) or S-nitroso-N-acetyl penicillamine (SNAP, 0.03–30 μM). However, L-NAME (0.3 mM) unmasked an inhibitory effect of DETCA pretreatment on vasorelaxation to SNAP in endothelium-intact vessels while markedly potentiating vasorelaxation to SNAP in control tissue.
5. L-NAME (0.3 mM)- and exogenous catalase (200 u ml⁻¹)-sensitive vasorelaxation to exogenous Cu/Zn SOD (200 u ml⁻¹) was greater after DETCA (10 mM) pretreatment in endothelium-intact aortic rings. This difference was abolished by catalase (200 u ml⁻¹).
6. In conclusion, tissue Cu/Zn SOD inhibition elicited a selective lesion in basal endothelial function in rat isolated aortic smooth muscle, consistent with the inactivation of basal NO by superoxide anion. The resulting leftward shift in nitrovasodilator reactivity, due to the loss of the tonic depression by basal NO, is likely to mask the inhibitory effect of superoxide anion on agonist-stimulated endothelial function and nitrovasodilator-derived NO, thereby accounting for the differential pattern of endothelial dysfunction after DETCA pretreatment.

     

NADPH oxidase isoform selective regulation of endothelial cell proliferation and survival

Proliferation and apoptosis of endothelial cells are crucial angiogenic processes that contribute to carcinogenesis and tumor progression. Emerging evidence implicates the regulation of proliferation and apoptosis by reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H₂O₂). In the present study, we investigated the roles of the ROS-generating Nox4- and Nox2-containing reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases in proliferation of human endothelial cells by examining the impact of these enzyme systems on (1) specific proliferative and tumorigenic kinases, extracellular regulated kinase1/2 (ERK1/2) and Akt, (2) cytoskeletal organization, and (3) the mechanisms that influence cellular apoptosis. ROS production and the expression of NADPH oxidase subunit Nox4, but not Nox2, were markedly higher in proliferating than in quiescent endothelial cells. Addition of the H₂O₂ scavenger catalase or downregulation of Nox4 protein with specific siRNA reduced ROS levels, cell proliferation, and ERK1/2 phosphorylation but had no effect on either cell morphology or caspase 3/7 activity. Although downregulation of Nox2 protein with siRNA also reduced ROS production and cell proliferation, it caused an increase in caspase 3/7 activity, reduced Akt phosphorylation, and caused cytoskeletal disorganization. Therefore, in endothelial cells, Nox4-derived H₂O₂ activates ERK1/2 to promote proliferation, whereas Nox2-containing NADPH oxidase maintains the cytoskeleton and prevents apoptosis to support cell survival. Our study provides a new understanding of the molecular mechanisms that underpin endothelial cell survival and a rationale for the combined suppression of Nox4- and Nox2-containing NADPH oxidases for unwanted angiogenesis in cancer.     

Role of nitric oxide during coronary endothelial dysfunction after myocardial infarction

This study aimed to investigate whether permanent ischaemia influences subacute vasodilatation responses of non-infarcted rat coronary vasculature, and to characterise these coronary changes. Ischaemia led to a significant impairment of the endothelium-dependent vasodilator response, while coronary vasodilatory capacity remained unaltered. In normal coronary circulation, nitric oxide (NO) and prostanoids contributed to vasodilatation, while basal involvement of endothelium-derived hyperpolarising factor was limited. Vasodilatory impairment following myocardial infarction did not originate from alterations in the prostanoid pathway, and only a slightly increased influence of K+ channels was observed. However, NO-mediated vasodilatation was significantly increased after ischaemia, as also confirmed by higher mRNA and protein levels of iNOS and eNOS. Additionally, the amount of superoxide was enhanced following infarction. We conclude that subacute postinfarction remodeling is accompanied by endothelial dysfunction in non-infarcted coronary arteries. Although the NO-mediated response is increased after ischaemia, its final action is restricted due to the presence of superoxide.     

吡格列酮联用阿托伐他汀对2型糖尿病患者血脂及血管内皮功能的影响

目的：观察吡格列酮联用阿托伐他汀对2型糖尿病患者血脂及血管内皮功能的影响。方法：选择2型糖尿病患者65例,随机分为对照组30例（A组）,接受常规降糖药治疗和阿托伐他汀10mg/d;实验组35例（B组）,在对照组基础上加用吡格列酮15mg/d,两组患者分别于治疗前、用药12周后检测血糖、糖化血红蛋白、血脂、血浆一氧化氮（NO）、内皮素-1（ET-1）的浓度、肱动脉内径变化率（FMD）。结果：治疗后两组患者的血糖水平均较治疗前明显降低,与治疗前比较差异有统计学意义（P〈0.01）,但两组间比较差异无统计学意义（P〉0.05）。两组患者ET-1水平有所降低（P〈0.05）,血浆NO水平和FMD均明显升高,与治疗前比较差异均有统计学意义（P〈0.01）;B组NO的升高水平和FMD较A组明显,两组比较差异均有统计学意义（P〈0.05）。治疗后两组患者体重指数均有所改善（P〈0.05,P〈0.01）。结论：吡格列酮联用阿托伐他汀能够更有效降低患者血脂水平,改善2型糖尿病患者血管内皮功能。     

Nitric oxide therapy For cardiovascular disease

Endothelium-derived NO is acknowledged as a key mediator of cardiovascular homeostasis. Indeed, an impairment in endothelial function resulting in limited NO bioavailability may contribute to a raft of vascular pathologies while a failure of peripheral 'nitrergic' neurovasodilator tone is implicated in erectile dysfunction. In addition to the established NO therapy exemplified by the use of nitrovasodilators, the endogenous NO pathway can now be therapeutically modulated to optimise endothelial or peripheral neuronal vasodilator function by inhibiting PDEV. A similar modulation of the NO pathway may also be clinically viable through the supplementation of precursors and cofactors of NO synthesis, the upregulation of endothelial NO synthase (eNOS) and the transfection of NOS genes to the vasculature.     

六味地黄丸对2型糖尿病患者血管内皮功能的影响

目的：探讨六味地黄丸对2型糖尿病患者血管内皮功能的影响。方法： 选择10例正常健康体检者和60例2型糖尿病患者,糖尿病者随机分为2组,对照组给予常规治疗,治疗组在常规西药治疗基础上加用六味地黄丸,疗程为12周,分别测定治疗前后血清一氧化氮（NO）和内皮收缩因子内皮素（ET-1）、超氧化物歧化酶（SOD）及谷胱甘肽过氧化物酶（GSH-Px）水平,同时行肱动脉介导内皮依赖性舒张功能的超声检测（FMD）。结果： 对照组与治疗组较正常体检组血清NO、SOD、GSH Px以及FMD水平降低,血清ET-1水平升高（P〈0.01）,两组较治疗前比较,治疗后血清NO、ET-1、SOD、GSH Px水平较治疗前改善（P〈0.05）,FMD值增高,此外,六味地黄丸组较对照组治疗后改善更明显,除FMD外差异有统计学意义（P〈0.05）。结论：在西药基础治疗上,六味地黄丸治疗能改善2型糖尿病患者血管内皮功能。     

小鼠内皮型一氧化氮合酶表达的变化与肾间质纤维化的关系

目的探讨内皮型一氧化氮合酶(eNOS)在小鼠单侧输尿管梗阻(UUO)模型肾组织中的变化及其与肾间质纤维化的关系。方法 48只小鼠随机均分为UUO模型组和假手术组,每组术后第1、3、7、14天分别处死6只小鼠,观察肾组织的病理改变,检测eNOS和结缔组织生长因子(CTGF)表达,计算管周毛细血管(PTC)密度。结果模型组术后第7天部分肾小管萎缩,纤维化形成;术后第14天肾小管间质纤维化更加明显。假手术组eNOS表达较多,CTGF低表达。与假手术组相比,模型组第7、14天eNOS表达减少(P<0.05),CTGF表达增多(P<0.05),第3-14天PTC密度下降(P<0.05)。结论小鼠UUO肾组织eNOS表达下降参与了肾间质纤维化的进展。     

The effectiveness, safety and epidemiology of the use of acarbose in the treatment of patients with type II diabetes mellitus A model of medicine-based evidence

Objective: To assess the efficacy, safety and extent of perceived indications of acarbose, a new antidiabetic agent, under routine clinical practice conditions in an unselected Northern Italian population of type II diabetic patients. Methods: The study population was assigned to three different groups according to the physician's clinical judgement: group A (acarbose considered as an elective treatment); group B (acarbose considered to be of uncertain benefit); group C (acarbose deemed not to be appropriate). Group B patients were randomized either to continue their standard treatment or to add acarbose to it. Patients with type II diabetes mellitus were recruited from 17 diabetes outpatient clinics from one Italian region (Lombardy). A total of 1027 patients were recruited (group A: 283; group C: 494; group B: 250, of whom 124 were randomly assigned to standard treatment + acarbose and 126 to standard treatment alone). Acarbose was administered for 1 year at a median dose of 100 mg 3 times daily. Drug efficacy was evaluated in terms of mean HbA1c, pre- and post-prandial glycaemic values. Additional endpoints were the proportion of patients with HbA1c levels below 8% at the end of the study period and the proportion of subjects who needed a modification in the standard treatment. The safety and tolerability profiles of the drug were also investigated. Data on HbA1c, fasting and post-prandial blood glucose levels were analysed over time using repeated-measures analysis [Generalized Estimating Equation (GEE) models]. Results: The analysis of Group B showed that, after treatment for 1 year, the mean reduction in HbA1c levels in the acarbose group with respect to the control group was 0.30% (95% confidence limits −0.60 +0.02; P = 0.07), while the mean reduction in post-prandial glycaemia was 17 mg · dl⁻¹ (95% c.l. −33.5 −0.8; P = 0.04). No difference resulted for fasting blood glucose levels. When looking at the baseline HbA1c levels, it emerged that the mean benefit associated with the use of acarbose was 0.14% (95% c.l. −0.6 +0.28; P = 0.5) in patients with HbA1c levels below 8%, 0.28% (95% c.l. −0.6 +0.05; P = 0.09) in those with values between 8% and 9.9% and 0.65% (95% c.l. −1.36 +0.06; P = 0.07) in those with values ≥10%. Only patients treated with diet ± oral anti-diabetic agents (OAA) benefited from acarbose treatment (mean benefit = 0.37%, 95% c.l. −0.65 −0.08), while no effect was shown for insulin-treated subjects. The proportion of patients with HbA1c below 8% increased from 31% to 44% in the acarbose group and from 40% to 45% in the control group (absolute difference between baseline and end-of-study values = 8.0% in favour of acarbose-treated patients; P = 0.058). Patients treated with acarbose were significantly more likely to undergo a dose reduction in concomitant diabetic treatments compared with the control group; they were also less likely to require an increase in the dose of standard treatment and to start insulin during the study period. One third of the patients could not assume the drug for the whole study period, mainly due to gastrointestinal side-effects. Conclusions: The design adopted in this study allowed an integrated evaluation of the overall effectiveness of acarbose in clinical practice. The benefits of the drug in an unselected population of non-insulin-dependent diabetes mellitus (NIDDM) patients are significant but of marginal clinical relevance. Only a better definition of the subgroups of patients who are more likely to benefit from long-term treatment, particularly through possible postponement of secondary OAA failure, will allow a reliable definition of the cost-effectiveness of this complementary component of anti-diabetic strategy. Received: 14 July 1998 / Accepted in revised form: 23 November 1998     

Tat-Mediated p66shc Transduction Decreased Phosphorylation of Endothelial Nitric Oxide Synthase in Endothelial Cells

We evaluated the role of Tat-mediated p66shc transduction on the activation of endothelial nitric oxide synthase in cultured mouse endothelial cells. To construct the Tat-p66shc fusion protein, human full length p66shc cDNA was fused with the Tat-protein transduction domain. Transduction of TAT-p66shc showed a concentration- and time-dependent manner in endothelial cells. Tat-mediated p66shc transduction showed increased hydrogen peroxide and superoxide production, compared with Tat-p66shc (S/A), serine 36 residue mutant of p66shc. Tat-mediated p66shc transduction decreased endothelial nitric oxide synthase phosphorylation in endothelial cells. Furthermore, Tat-mediated p66shc transduction augmented TNF-α-induced p38 MAPK phosphorylation in endothelial cells. These results suggest that Tat-mediated p66shc transduction efficiently inhibited endothelial nitric oxide synthase phosphorylation in endothelial cells.     

Nitric oxide and superoxide interactions in the kidney and their implication in the development of salt-sensitive hypertension

1. Enhanced superoxide (O2(-)) activity as a result of the inhibition of the superoxide dismutase (SOD) enzyme results in vasoconstrictor and antinatriuretic responses in the canine kidney; these responses were shown to be greatly enhanced during inhibition of nitric oxide synthase (NOS). Glomerular filtration rate remained mostly unchanged during SOD inhibition in the intact nitric oxide (NO) condition, but was markedly reduced during NOS inhibition. These findings indicate that endogenous NO has a major renoprotective effect against O2(-) by acting as an anti-oxidant. Nitric oxide synthase inhibition was also shown to enhance endogenous O2(-) activity. 2. Experiments in our laboratory using dogs, rats and gene knockout mice have shown that renal vasoconstrictor and antinatriuretic responses to acute or chronic angiotensin (Ang) II administration are mediated, in part, by O2(-) generation. In the absence of NO, enhanced O2(-) activity largely contributes to AngII-induced renal tubular sodium reabsorption. Acute or chronic treatment with the O2(-) scavenger tempol in experimental models of hypertension (induced by chronic low-dose treatment with AngII and NO inhibitors) causes an improvement in renal haemodynamics and in excretory function, abolishes salt sensitivity and reduces blood pressure. 3. The present mini review also discusses related studies from many other laboratories implicating a role for O2(-) and its interaction with NO in the development of salt-sensitive hypertension. 4. Overall, the collective data support the hypothesis that an imbalance between the production of NO and O2(-) in the kidney primarily determines the condition of oxidative stress that alters renal haemodynamics and excretory function leading to sodium retention and, thus, contributes to the development of salt-sensitive hypertension.     

阿魏酸哌嗪对2型糖尿病血管内皮细胞的保护及功能调节的临床研究

目的：探讨阿魏酸哌嗪防治2型糖尿病血管内皮损伤及功能调节的作用。方法：80例患者随机分成2组,治疗组（阿魏酸哌嗪片加常规降糖治疗,n=37）和对照组（维生素C片加常规降糖治疗,n=43）,疗程4周,并检测空腹血糖（FBG）、糖基化血红蛋白（HbA1C）、循环血内皮细胞（CEC）、血清过氧化脂质（LPO）、内皮素（ET）、NO、组织纤溶酶原激活物（t-PA）。结果：治疗组CEC、LPO、ET在治疗后明显下降,与对照组比较差异有统计学意义（P〈0.01） 治疗组NO、t-PA在治疗后明显上升,与对照组比较差异有统计学意义（P〈0.01）。结论：常规降糖治疗联用阿魏酸哌嗪可明显保护2型糖尿病患者的血管内皮细胞,并可调节其功能状态。     

Nitric oxide, adenosine deaminase, xanthine oxidase and superoxide dismutase in patients with panic disorder: alterations by antidepressant treatment

OBJECTIVE: In the present study, we aimed to investigate whether nitric oxide (NO) levels and activities of xanthine oxidase (XO), superoxide dismutase (SOD), and adenosine deaminase (ADA) are associated with Panic disorder (PD) as well as impact of psychopharmacological treatments on NO, SOD, ADA, and XO levels in PD. METHOD: In this study, 32 patients and 20 healthy controls were included. The serum levels of NO, XO, SOD, and ADA were measured in the patients and controls. The patients were treated with antidepressant. RESULTS: ADA and XO levels of the patients were significantly higher than the controls. SOD levels of the patients were significantly lower than the controls but the difference was not statistically significant. Although NO levels of the patients were higher than the controls, the difference was not statistically significant. There was no correlation between PAS and the parameters studied (SOD, ADA, XO, and NO) of the patients. After 8 weeks of antidepressant treatment, ADA and SOD activities were increased whereas NO and XO levels decreased significantly. CONCLUSION: ADA, XO activity may have a pathophysiological role in PD, and prognosis of PD. Activity of these enzymes may be used to monitor effects of the antidepressant treatment.     

芝麻素对2型糖尿病大鼠主动脉内皮功能的保护作用

目的探讨芝麻素改善2型糖尿病大鼠主动脉内皮功能损伤的作用及可能机制。方法采用长期高脂饮食加小剂量链脲佐菌素(streptozotocin,STZ)建立2型糖尿病大鼠模型。灌服不同剂量芝麻素(120、60 mg.kg-1.d-1)8周后处死动物。离体血管灌流法测大鼠主动脉内皮依赖性舒张反应及NO生物活性,测血清丙二醛(malondialdehyde,MDA)含量和总抗氧化能力(total antioxidative capacity,T-AOC),Western blot测主动脉内皮型一氧化氮合酶(endothelial nitricoxide synthase,eNOS)、硝基酪氨酸(nitrotyrosine,NT)和还原型辅酶Ⅱ(NADPH)氧化酶亚基P47phox蛋白表达。结果与模型组相比,芝麻素(120 mg.kg-1.d-1)组内皮依赖性血管舒张功能增强,NO活性升高;血清MDA含量降低,T-AOC水平升高;主动脉eNOS蛋白表达增高,NT和P47phox蛋白表达降低。结论芝麻素可改善糖尿病大鼠血管内皮功能,其机制与上调血管eNOS表达和减轻NO氧化失活有关。     

2,4,6-Trinitrotoluene inhibits endothelial nitric oxide synthase activity and elevates blood pressure in rats

2,4,6-Trinitrotoluene (TNT), which is widely used in explosives, is an important occupational and environmental pollutant. Human exposure to TNT has been reported to be associated with cardiovascular dysfunction, but the mechanism is not well understood. In this study, we examine the endothelial nitric oxide synthase (eNOS) activity and blood pressure value following TNT exposure. With a crude enzyme preparation, we found that TNT inhibited the enzyme activity of eNOS in a concentration-dependent manner (IC₅₀ value=49.4 μM). With an intraperitoneal administration of TNT (10 and 30 mg/kg) to rats, systolic blood pressure was significantly elevated 1 h after TNT exposure (1.2- and 1.3-fold of that of the control, respectively). Under the conditions, however, experiments with the inducible NOS inhibitor aminoguanidine revealed that an adaptive response against hypertension caused by TNT occurs. These results suggest that TNT is an environmental chemical that acts as an uncoupler of constitutive NOS isozymes, resulting in decreased nitric oxide formation associated with hypertension in rats.     

同型半胱氨酸对内皮细胞一氧化氮合酶活力及基因表达的影响

目的 观察同型半胱氨酸(Hcy)对培养的人脐静脉内皮细胞(HUVEC)一氧化氮合酶(eNOS)活力及其基因表达的动态影响.方法 10、30、100、300 μmol · L-1Hcy与HUVEC分别培养24、48、72 h后,用HPLC测定细胞内不对称二甲基精氨酸(ADMA)的含量,反转录聚合酶链反应(RT-PCR)检测细胞内eNOS mRNA的表达,并分别测定细胞二甲基精氨酸二甲基氨基水解酶(DDAH)、eNOS的活力和NO的含量.结果 HUVEC经不同浓度Hcy分别处理24、48、72 h后,其细胞内ADMA聚积增多,DDAH活性和eNOS活力降低,NO生成减少,且呈时间和浓度依赖性.但只有100 μmol · L-1 Hcy与HUVEC作用72 h时,才引起eNOS mRNA表达的减少.结论 Hcy对内皮功能的损伤可能通过抑制DDAH活性,引起ADMA聚积,从而降低eNOS活力,导致NO生成减少.此外,eNOS mRNA表达的抑制也是Hcy诱导的内皮功能障碍的机制之一.     

The PPARgamma ligand, rosiglitazone, reduces vascular oxidative stress and NADPH oxidase expression in diabetic mice

Oxidative stress plays an important role in diabetic vascular dysfunction. The sources and regulation of reactive oxygen species production in diabetic vasculature continue to be defined. Because peroxisome proliferator-activated receptor gamma (PPARgamma) ligands reduced superoxide anion (O(2)(-.)) generation in vascular endothelial cells in vitro by reducing NADPH oxidase and increasing Cu/Zn superoxide dismutase (SOD) expression, the current study examined the effect of PPARgamma ligands on vascular NADPH oxidase and O(2)(-.) generation in vivo. Lean control (db(+)/db(-)) and obese, diabetic, leptin receptor-deficient (db(-)/db(-)) mice were treated with either vehicle or rosiglitazone (3 mg/kg/day) by gavage for 7-days. Compared to controls, db(-)/db(-) mice weighed more and had metabolic derangements that were not corrected by treatment with rosiglitazone for 1-week. Aortic O(2)(-.) generation and mRNA levels of the NADPH oxidase subunits, Nox-1, Nox-2, and Nox-4 as well as Nox-4 protein expression were elevated in db(-)/db(-) compared to db(+)/db(-) mice, whereas aortic Cu/Zn SOD protein and PPARgamma mRNA levels were reduced in db(-)/db(-) mice. Treatment with rosiglitazone for 1-week significantly reduced aortic O(2)(-.) production and the expression of Nox-1, 2, and 4 but failed to increase Cu/Zn SOD or PPARgamma in aortic tissue from db(-)/db(-) mice. These data demonstrate that the vascular expression of Nox-1, 2, and 4 subunits of NADPH oxidase is increased in db(-)/db(-) mice and that short-term treatment with the PPARgamma agonist, rosiglitazone, has the potential to rapidly suppress vascular NADPH oxidase expression and O(2)(-.) production through mechanisms that do not appear to depend on correction of diabetic metabolic derangements.     

Functional relevance of genetic variations of endothelial nitric oxide synthase and vascular endothelial growth factor in diabetic coronary microvessel dysfunction

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Angiotensin II type 1 receptor blockade attenuates gefitinib-induced cardiac hypertrophy via adjusting angiotensin II-mediated oxidative stress and JNK/P38 MAPK pathway in a rat model

Gefitinib is a tyrosine kinase inhibitor (TKI) of the epidermal growth factor receptor (EGFR), used for the treatment of advanced or metastatic non-small cell lung cancer. Recently, studies proved that Gefitinib-induced cardiotoxicity through induction of oxidative stress leads to cardiac hypertrophy. The current study was conducted to understand the mechanisms underlying gefitinib-induced cardiac hypertrophy through studying the roles of angiotensin II (AngII), oxidative stress, and mitogen-activated protein kinase (MAPK) pathway. Male Wistar albino rats were treated with valsartan, gefitinib, or both for four weeks. Blood samples were collected for AngII and cardiac markers measurement, and hearts were harvested for histological study and biochemical analysis. Gefitinib caused histological changes in the cardiac tissues and increased levels of cardiac hypertrophy markers, AngII and its receptors. Blocking of AngII type 1 receptor (AT1R) via valsartan protected hearts and normalized cardiac markers, AngII levels, and the expression of its receptors during gefitinib treatment. valsartan attenuated gefitinib-induced NADPH oxidase and oxidative stress leading to down-regulation of JNK/p38-MAPK pathway. Collectively, AT1R blockade adjusted AngII-induced NADPH oxidase and JNK/p38-MAPK leading to attenuation of gefitinib-induced cardiac hypertrophy. This study found a pivotal role of AngII/AT1R signaling in gefitinib-induced cardiac hypertrophy, which may provide novel approaches in the management of EGFRIs-induced cardiotoxicity.