一氧化氮在哮喘发病机制中的作用

目的通过观察一氧化氮合成酶（ＮＯＳ）抑制剂亚硝基左旋精胺酸甲酯（Ｌ－ＮＡＭＥ）对豚鼠离体气管张力收缩的影响及采用组织化学方法观察ＮＯＳ在豚鼠哮喘模型肺中的分布，了解一氧化氮（ＮＯ）在哮喘发病机制中的作用。方法用Ｌ－ＮＡＭＥ孵育豚鼠离体气管段后，观察对组织胺量效曲线的影响并与对照组比较；另用还原型辅酶ＮＡＤＰＨ－ｄ对豚鼠哮喘模型肺组织行组织化学染色。结果豚鼠离体气管段经Ｌ－ＮＡＭＥ孵育后，组胺诱发的张力曲线明显左移，其最大反应张力是对照组的１７０％（Ｐ＜０．０１）。ＮＡＤＰＨ组化染色可见哮喘模型组肺泡巨噬细胞显著增多，ＮＯＳ染色呈明显阳性反应，对照组肺泡巨噬细胞数极少，且未见ＮＯＳ染色阳性者。结论Ｌ－ＮＡＭＥ使组胺对豚鼠离体气管段收缩张力显著增加，通过增加ＮＯ生成可降低气道对组胺的反应性；哮喘时肺泡巨噬细胞显著增多，且ＮＯＳ染色呈明显阳性。提示在巨噬细胞中的ＮＯＳ作用下产生的ＮＯ在哮喘发病中起重要作用。     

重型肝炎患者外周血内皮素及一氧化氮水平变化的意义

目的探讨内皮素（ＥＴ）和一氧化氮（ＮＯ）在重型肝炎（ＳＨ）发病中的作用．方法检测３０例ＳＨ,３２例慢性肝炎（ＣＨ）患者外周血ＥＴ和ＮＯ代谢物ＮＯ－２的水平,并用ＮＯ合成酶底物左旋精氨酸（ＬＡｒｇ）进行治疗前后对比．结果ＳＨ患者外周血ＥＴ和ＮＯ－２水平（１３９ｎｇ／Ｌ±１４ｎｇ／Ｌ,１２７μｍｏｌ／Ｌ±４０μｍｏｌ／Ｌ）明显高于ＣＨ组（８５ｎｇ／Ｌ±１５ｎｇ／Ｌ,６３μｍｏｌ／Ｌ±２５μｍｏｌ／Ｌ,Ｐ＜００１）．合并有Ⅲ,Ⅳ期肝性脑病与肝肾综合征患者外周血ＥＴ和ＮＯ－２水平（１４９ｎｇ／Ｌ±１３ｎｇ／Ｌ,１６２μｍｏｌ／Ｌ±３４μｍｏｌ／Ｌ）明显高于非肝性脑病患者（１１５ｎｇ／Ｌ±１２ｎｇ／Ｌ,８８μｍｏｌ／Ｌ±２４μｍｏｌ／Ｌ,Ｐ＜００１）和Ⅱ期肝性脑病患者（１３６ｎｇ／Ｌ±１０ｎｇ／Ｌ,１２２μｍｏｌ／Ｌ±２６μｍｏｌ／Ｌ,Ｐ＜００１）;ＬＡｒｇ静脉滴注后血浆ＥＴ水平和平均动脉压（ＭＡＰ）显著下降,而肌酐清除率（ｃＣｒ）和尿钠含量明显增加．结论ＥＴ和ＮＯ水平升高是引起ＳＨ多脏器功能障碍的重要因素．ＬＡｒｇ长期治疗可能促进ＳＨ患者脑水肿形成和肝肾综合征发生．     

一氧化氮对缺氧性肺动脉高压大鼠血浆降钙素基因相关肽？…

目的 探讨一氧化氮（ＮＯ）对缺氧性肺动态高压（ＨＰＨ）大鼠血浆降钙素基因相关肽（ＣＧＲＰ）含量的影响。方法 将Ｗｉｓｔａｒ大鼠４０只分为四组：对照组（ｎ＝１０）,缺氧组（ｎ＝１０）,缺氧＋Ｌ－ＮＡＭＥ组（ｎ＝１０）,缺年头＋Ｌ－Ａｒｇ组（ｎ＝１０）。通过Ｐ５０压力传感器测量定四组大鼠肺动脉平均压（ＰＡＭＰ）,缺氧＋Ｌ－Ａｒｇ组的ＰＡＭＰ显著低于缺氧组（Ｐ〈０．０５）;缺氧组的右室（ＲＶ）干重／左室     

L－精氨酸逆转一氧化氮抑制后的犬冠脉血流动力学改变和内皮素－1含量升高

观察了犬冠脉内灌注Ｎ－单甲基左旋精氨酸（Ｌ－ＮＭＭＡ）后再灌注Ｌ－精氨酸（Ｌ－Ａｒｇ）和单独灌注Ｌ－ＮＭＭＡ前后冠脉血流动力学、冠脉血流储备以及冠脉对不同浓度的乙酰胆碱（Ａｃｈ）反应的变化，同时用放免法测定冠脉前降支（ＬＡＤ）伴行静脉血中内皮素－１（ＥＴ－１）含量。结果发现，Ｌ－Ａｒｇ完全逆转了灌注Ｌ－ＮＭＭＡ引起的血流动力学改变，使心率回升，下降的基础冠脉流量（ＣＢＦ），从２０±８ｍｌ／ｍｉｎ回升至２８±７ｍｌ／ｍｉｎ，Ｐ＜０．０５），降低的冠脉储备恢复，从５１±１０ｍｌ／ｍｉｎ升至９４±１５ｍｌ／ｍｉｎ，Ｐ〈０．０１），ＥＴ－１的含量不再升高，从１５．５±３．０ｎｇ／Ｌ下降至５．０±２．０ｎｇ／Ｌ，Ｐ〈０．０１），Ａｃｈ介导的ＣＢＦ增加不再受到抑制（Ｐ〈０．０１）。结果提示提供外源性Ｌ－Ａｒｇ可增加一氧化氮（ＮＯ）的产生，使由于ＮＯ抑制而产生的血流动力学改变和ＥＴ－１升高发生逆转。     

8—甲氧基补骨脂素对人离体肺动脉收缩的影响

目的通过观察８－甲氧基补骨脂素（８－ＭＯＰ）对人肺动脉收缩的影响，探讨８－ＭＯＰ舒张肺动脉的作用和机制，为８－ＭＯＰ进一步用于降低肺动脉高压提供客观依据。方法采用离体肺动脉平滑肌收缩的实验方法。结果（１）２×１０－５ｍｏｌ／Ｌ的８－ＭＯＰ可使１０－６ｍｏｌ／Ｌ的去甲肾上腺素（ＮＡ）所致收缩的肺动脉环舒张原张力的８８％，其中７例无血管内皮者舒张８３％，４例内皮细胞完好者舒张９７％；（２）经２×１０－５ｍｏｌ／Ｌ的８－ＭＯＰ预处理肺动脉环后，１０－６ｍｏｌ／Ｌ的ＮＡ收缩肺动脉环张力被抑制８９％；（３）上述浓度的８－ＭＯＰ可使ＮＡ收缩肺动脉环的累积量－效曲线不平行右移，最大收缩反应被抑制５５％，抑制参数ＰＤ′２为４．７９。结论提示８－ＭＯＰ有理想的舒张人肺动脉作用，其作用可不依赖于肺动脉内皮细胞的存在，８－ＭＯＰ有可能会成为一种有效降低肺动脉高压药物。     

一氧化氮在高脂饲养兔胸主动脉的变化和意义

观察高脂饲养兔胸主动脉血管环对去甲肾上腺素（ＮＥ）的反应性及环磷酸鸟苷（ｃＧＭＰ）含量的变化。结果表明其对ＮＥ的反应性降低，组织ｃＧＭＰ的含量减少。左旋精氨酸（Ｌ－Ａｒｇ）和硝普钠（ＳＮＰ）可恢复此反应性，而一氧化氮合成酶（ＮＯＳ）阻滞剂Ｌ－硝基精氨酸（Ｌ－ＮＮＡ）却加重其降低的反应性。提示高脂饲养兔血管环中的一氧化氮（ＮＯ）减少，Ｌ－Ａｒｇ及ＳＮＰ可以逆转之，暗示Ｌ－Ａｒｇ／ＮＯ通路障碍可能是动脉粥样硬化的又一机理。     

L－精氨酸逆转一氧化氮抑制后的犬冠脉血流动力学改变和内皮素－1含量升高

观察了犬冠脉内灌注Ｎ－单甲基左旋精氨酸（Ｌ－ＮＭＭＡ）后再灌注Ｌ－精氨酸（Ｌ－Ａｒｇ）和单独灌注Ｌ－ＮＭＭＡ前后冠脉血流动力学、冠脉血流储备以及冠脉对不同浓度的乙酰胆碱（Ａｃｈ）反应的变化，同时用放免法测定冠脉前降支（ＬＡＤ）伴行静脉血中内皮素－１（ＥＴ－１）含量。结果发现，Ｌ－Ａｒｇ完全逆转了灌注Ｌ－ＮＭＭＡ引起的血流动力学改变，使心率回升，下降的基础冠脉流量（ＣＢＦ），从２０±８ｍｌ／ｍｉｎ回升至２８±７ｍｌ／ｍｉｎ，Ｐ＜０．０５)，降低的冠脉储备恢复，从５１±１０ｍｌ／ｍｉｎ升至９４±１５ｍｌ／ｍｉｎ，Ｐ〈０．０１)，ＥＴ－１的含量不再升高，从１５．５±３．０ｎｇ／Ｌ下降至５．０±２．０ｎｇ／Ｌ，Ｐ〈０．０１)，Ａｃｈ介导的ＣＢＦ增加不再受到抑制（Ｐ〈０．０１）。结果提示提供外源性Ｌ－Ａｒｇ可增加一氧化氮（ＮＯ）的产生，使由于ＮＯ抑制而产生的血流动力学改变和ＥＴ－１升高发生逆转。     

高血压病人血小板L—精氨酸／一氧化氮系统的改变

目的原发性高血压（ＥＨ）病人（２３例）与健康成年人（１４）例作对照，观察高血压时血小板（Ｐｔ）左旋精氨酸（Ｌ－Ａｒｇ）－一氧化氮（ＮＯ）系统的改变及Ｌ－Ａｒｇ转运的特征。方法微盘测定法测定血小板孵育液中亚硝酸盐（ＮＯ２－）的含量来反映ＮＯ产生量、ＡＤＰ刺激下ＮＯ的产生量；采用张新波等建立的一氧化氮合酶（ＮＯＳ）测定改良法测定血小板ＮＯＳ活性；放射性同位素标记测定血小板３Ｈ－Ｌ－Ａｒｇ转运的动力学特征。结果ＥＨ患者Ｐｔ的ＮＯ产生量及ＮＯＳ活性较对照组明显降低（Ｐ＜０．０１），用ＡＤＰ刺激后，ＥＨ患者Ｐｔ的ＮＯ增加量仅为正常对照组增加量的６０％，其Ｌ－Ａｒｇ转运能力亦显著低于正常人（各浓度点Ｐ均＜０．０１）。最大转运速率（Ｖｍａｘ）仅为正常人的７９％（Ｐ＜０．０１），而米氏常数（Ｋｍ）则无明显改变（Ｐ＞０．０５）。结论高血压时Ｐｔ的Ｌ－Ａｒｇ－ＮＯ系统存在明显异常，提示对ＥＨ患者，在降压的同时，联合应用改善Ｌ－Ａｒｇ－ＮＯ系统的药物，对预防和治疗高血压减少并发症可能会有更好的效果。     

一氧化氮在肝损伤中作用的实验研究

材料与方法：１．动物模型的复制及分组：雄性ｗｉｓｔａｒ大鼠,随机分成六组。除正常对照组外,各组均给予１０％Ｄ－半乳糖胺（Ｄ－Ｇａ１Ｎ）０．６ｇ／ｋｇ及大肠杆菌Ｏ１１１Ｂ４脂多糖（ＬＰＳ）０．１ｍｇ／ｋｇ腹腔注射,造成大鼠急性肝损伤模型。并分别于给Ｄ－ＧａｌＮ前２０分钟及后６小时、１１小时,精氨酸（Ａｒｓ）组给子Ｌ－Ａｒｇ０．５ｇ／ｋｇ腹腔注射;Ａｒｇ一硝基精氨酸甲酯（ＮＡＭＥ）组给予Ｌ－Ａｒｇ０．５ｇ／ｋｇ加Ｌ一ＮＡＭＥ５０ｍｇ／ｋｇ;ＮＡＭＥ组给予Ｌ－ＮＡＭＥ１０ｍｇ／ｋｇ;地塞米松（Ｄｅｘ）…     

胰岛素抵抗高血压大鼠血小板L—精氨酸／一氧化氮系统的改变

目的 观察胰岛素抵抗高血压大鼠血小板Ｌ－精氨酸／一氧化氮系统的改变。方法 自发性高血压大鼠（ＳＨＲ）自第５周至第１０周喂信果糖,制备胰岛素抵抗高血压大鼠（ＩＲ）模型。在此模型上,检测血小板一氧化氮合酶（ＮＯＳ）活性、一氧化氮（ＮＯ）产生量及Ｌ－精氨酸（Ｌ－Ａｒｇ）转运特征,同时观察了血浆Ｌ－Ａｒｇ水平、心纳素（ＮＡＰ）、ＮＯ水平及ｃＧＭＰ水平。结果 ＳＨＲ大鼠收缩压（ＳＢＰ）（Ｐ〈０．０１）,血浆     

Alterations in the Vasoreactivity of Hypertensive Rat Aortic Rings: Role of Nitric Oxide and Superoxide Radicals

Objectives:Present study was undertaken to investigate involvement of nitric oxide (NO) and superoxide radicals in the modulation of vasoreactivity in a model of renal hypertension

Method:Hypertension was induced in the male Sprague Dawley rats by aortic banding just above the left kidney. Relaxation or contraction following cumulative addition of acetylcholine (Ach, 1 × 10^-8to 1 x^-5M) or phenylephrine (PE, 1 × 10^-8to 1 × 10^-5mol/1) was studied in the aortic rings obtained from sharn operated normotensive, hypertensive and captopril pretreated rats. Ach and PE responses were taken in the presence or absence of NO synthase inhibitor (L-NAME; 1 × 10^-5and 1 × 10^-4mol/1). Spontaneous release of NO from the aortic rings was evaluated by studying the inhibition of adenosine phosphate stundated platelet aggregation, while superoxide radcals were estunated by cytochrome c reduction method

Results:Ach induced vasorelaxation in PE precontracted rings was impaired followmg 8 wk alter aorbc bandmg, while spontaneous release of NO remained unaffected. Captopril pretreatment restored the aortic ring responsiveness to Ach. An increase in the superoxide radicalgeneration and PE induced contraction following L-NAME treatment in the hypertensive rat aortic rings was observed

Conclusion:Attenuation in the Ach induced NO release and augmentation in the superoxide radcal generation seems to play an important role in the modulation of vasoreactivity following renal hypertension in rats     

一氧化氮对自发性高血压大鼠血管内皮功能的作用

目的　探讨自发性高血压大鼠 (SHR)内皮舒张功能不全的发生机制。方法　采用体外灌注的方法测定大鼠胸主动脉环对不同浓度乙酰胆碱的舒张反应变化 ,并测定血清中NO-3浓度和动脉组织中环鸟苷酸水平。结果　与魏 凯二氏大鼠 (WKY)比较 ,SHR胸主动脉环对乙酰胆碱的舒张反应明显减弱。左旋硝基精氨酸 (L NNA)可明显抑制大鼠胸主动脉环对乙酰胆碱的舒张反应 ,但并不能消除SHR和WKY对乙酰胆碱舒张反应之间的差异。与WKY比较 ,SHR血中NO-3水平明显降低 (P<0 .0 1) ,动脉组织中环鸟苷酸含量降低 (P<0 .0 1)。结论　SHR内皮依赖的血管舒张功能减低 ;一氧化氮 (NO)的生成或释放不足可能直接参与了SHR血管内皮依赖的舒张功能不全。     

Endothelial dysfunction: Possible mechanisms and ways of correction

BACKGROUND: Endothelial function is impaired in atherosclerosis, hypertension, diabetes and aging, and this may be associated with an attenuated ability of endothelial cells to generate nitric oxide (NO). OBJECTIVES: To evaluate possible alterations in endothelium-dependent relaxation in rat aortic rings, the activity of constitutive NO synthase and endothelial electrical responses to acetylcholine (Ach) in rat aorta, and the effect of one month of treatment with the angiotensin-converting enzyme inhibitor enalapril on endothelial function. METHODS: Endothelial membrane potential was measured in excised rat aorta using the perforated patch-clamp technique. Enzyme activity was determined by measuring the rate of formation of L-citrulline from L-arginine. RESULTS: In old rats and rats with experimental diabetes, the relaxation response to Ach and the activity of constitutive NO synthase were significantly depressed compared with control rats, and the endothelial resting membrane potential was significantly depolarized (-32.7+/-0.8 mV and -28.4+/-3.1 mV, respectively) compared with the control rats (-42.9+/-0.6 mV). The membrane potential attained during peak hyper-polarization to Ach in the arteries of diabetic and old rats (-57.6+/-1.1 mV and -55.7+/-2.1 mV, respectively) did not reach the level attained in the arteries of control rats (-63.1+/-0.6 mV). Enalapril treatment restored the relaxation response to Ach and increased the activity of constitutive NO synthase in aortic rings from diabetic and old rats. CONCLUSIONS: Altered electrical properties of endothelial cells and attenuated NO synthase activity underpin the suppressed relaxation to Ach in aging and experimental diabetes. Enalapril treatment improves endothelium-dependent relaxation and the activity of constitutive NO synthase.     

植物雌激素α-玉米赤霉醇内皮依赖性舒张效应的机制研究

目的探讨植物雌激素α-玉米赤霉醇(α-ZAL)对大鼠胸主动脉环内皮依赖性舒张效应中一氧化氮合酶(NOS)-NO-环磷酸鸟苷(cGMP)系统的作用。方法采用体外血管环灌流的方法,先用10-6mol/L苯肾上腺素预收缩血管。观察10-10～10-5mol/L6个不同浓度α-ZAL对内皮完整和去除内皮的大鼠胸主动脉环的舒张作用。α-ZAL10-10～10-8mol/L为低浓度组,α-ZAL10-7～10-5mol/L为高浓度组,0.1%乙醇浓度为对照组。在高浓度组中分别预先加用10-5mol/L左旋硝基精氨酸甲酯(L-NAME组)和亚甲蓝(MB组)并观察其影响,测定动脉环中内皮型一氧化氮合酶(eNOS)和cGMP含量及灌流液中NO含量变化。结果L-NAME组和MB组均可减弱高浓度组中α-ZAL的内皮依赖性胸主动脉环舒张作用(P<0.05,P<0.01);与对照组比较,高浓度组胸主动脉环中eNOS、cGMP含量及灌流液中NO含量增高(P<0.05,P<0.01);与高浓度组比较,L-NAME组可降低灌流液中NO含量及胸主动脉环中cGMP含量(P<0.05,P<0.01);MB组可降低胸主动脉环中cGMP含量(P<0.01)。结论α-ZAL的内皮依赖性舒张作用与NOS-NO-cGMP系统的激活有关。     

The protective role of epithelium-derived nitric oxide in isolated bovine trachea

Airway epithelial cells from bovine airways can release relaxant factors such as nitric oxide (NO) and prostaglandin E(2) and the removal of airway epithelium results in an increased responsiveness of smooth muscle to spasmogen stimuli. In this study, we assessed whether or not epithelial NO modulates the contractile response of bovine trachea in vitro.Cumulative concentration-response curves to acetylcholine (ACh), histamine (Hist) and 5-hydroxytryptamine (5-HT) were obtained in both intact and epithelium denuded tracheal strips in the presence of indomethacin (10 microM).In intact, but not in epithelium denuded strips, preincubation with the NO synthase inhibitor L-N((G))-Nitro-arginine methyl ester (L-NAME), but not with D-NAME, shifted to the left the concentration-response curve to ACh (pD(2) values in the absence and in the presence of L-NAME were 3.47+/-0.1 and 4.60+/-0.1, respectively; P<0.05) and to Hist (pD(2) in the absence and in the presence of L-NAME: 3.89+/-0.1 and 4.54+/-0.1, respectively; P<0.05). This effect was reversed by L-arginine (1mM), but not by D-arginine. The contractile response to 5-HT was not affected by L-NAME in either intact or epithelium denuded strips.These data suggest that NO is an epithelial relaxant factor modulating airway cholinergic and histaminergic contraction of bovine trachea and that the activation of the epithelial NO synthase is a mediator-specific process.     

Ferulic acid restores endothelium-dependent vasodilation in aortas of spontaneously hypertensive rats

BACKGROUND: Ferulic acid (FA), a phytochemical constituent, has antihypertensive effects, but a detailed understanding of its effects on vascular function remains unclear. The vasoreactivity of FA was assessed using aortic rings isolated from normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). METHODS: The effects of FA (10(-5) to 10(-3) mol/L) on vasodilatory responses were evaluated based on contractile responses induced by phenylephrine (10(-6) mol/L) in thoracic aortic rings from male WKY rats and SHR. Basal nitric oxide (NO) bioavailability in the aorta was determined from the contractile response induced by the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 10(-4) mol/L). The effects of FA on the production of NADPH-dependent superoxide anion were examined in SHR aortas. The impact of hydroxyhydroquinone, a generator of superoxide anions, on the FA-induced enhancement in acetylcholine-stimulated vasodilation was also investigated. RESULTS: The FA (10(-3) mol/L)-induced relaxation was partially blocked by removal of the endothelium or by pretreating SHR aortas with L-NAME. FA increased NO bioavailability, and decreased NADPH-dependent superoxide anion levels in SHR aortas. Ferulic acid improved acetylcholine-induced endothelium-dependent vasodilation in SHR, but not in WKY. Furthermore, the simultaneous addition of hydroxyhydroquinone significantly inhibited the increase in acetylcholine-induced vasodilation by FA. CONCLUSIONS: Ferulic acid restores endothelial function through enhancing the bioavailability of basal and stimulated NO in SHR aortas. The results explain, in part, the mechanisms underlying the effects of FA on blood pressure (BP) in SHR.     

Pioglitazone, a PPARgamma agonist, restores endothelial function in aorta of streptozotocin-induced diabetic rats

OBJECTIVE: To study the effect of pioglitazone (a PPAR gamma agonist) treatment on blood pressure, endothelial function, and oxidative stress in streptozotocin (STZ)-induced diabetic rats. METHODS: Sprague-Dawley rats were randomized into control (n=32) and STZ-diabetic (n=32) groups. Rats were further randomized to receive pioglitazone (10 mg/kg) or placebo for 4 weeks, and the following protocols were carried out. Blood pressure, blood glucose level, and body weight were measured. Thoracic aorta was isolated and the dose-response curve of phenylephrine (PE) in the presence or absence of Nomega-nitro-L-arginine-methyl ester (L-NAME) was recorded. The dose-response curve of acetylcholine (Ach) in the presence or absence of indomethacin, L-NAME, and methylene blue was recorded. Tone-related basal nitric oxide release experiments were carried out. Lipid peroxidation, superoxide dismutase, catalase, and reduced glutathione were estimated in liver, kidney, and aorta. Aortic nitrite levels were also measured. Further, in vitro effects of PE and Ach in the presence of pioglitazone (0.1 M-10 mM) were measured in aortic rings of nondiabetic and STZ-diabetic rats. Pioglitazone-induced relaxations were recorded in PE-contracted rings (with intact and denuded endothelium) in the presence of L-NAME and in KCl-contracted rings. RESULTS: Pioglitazone treatment reduced blood pressure without having any significant effect on blood glucose level and body weight of STZ-diabetic rats. Enhanced PE-induced contraction and impaired Ach-induced relaxations in STZ-diabetic rats were restored to normal by pioglitazone treatment. The presence of L-NAME but not indomethacin blocked Ach-induced relaxation in pioglitazone-treated STZ-diabetic rats. Basal nitric oxide release was significantly higher in pioglitazone-treated STZ-diabetic rats. Oxidative stress was significantly higher in STZ-diabetic rats and pioglitazone treatment significantly reduced it. High aortic nitrite levels of STZ-diabetic rats were significantly reduced by pioglitazone treatment. The presence of pioglitazone at higher concentrations (>10 muM), but not at lower concentrations, significantly changed the dose-response curve of PE or Ach. Pioglitazone relaxations at lower concentrations but not at higher concentrations were blocked by endothelium removal or by the presence of L-NAME. CONCLUSION: Pioglitazone administration reduced oxidative stress, which prevented the breakdown of nitric oxide and increased nitric oxide levels, thereby restoring the endothelial function in aorta of STZ-diabetic rat. Hence, from the present study it can be concluded that pioglitazone administration in STZ-diabetic rats lowers blood pressure, protects against oxidative stress, and restores endothelial function.     

肾血管性高血压大鼠血管内皮细胞功能的变化

目的观察肾血管性高血压(RVH)大鼠血管内皮细胞功能的变化并探讨其机制。方法体重为160~180g健康雄性Wistar大鼠随机分成2组高血压模型(RVH)组及对照(C)组。术后4周,用颈动脉直接插管法测定大鼠血压,应用生物测定法观察大鼠离体主动脉舒缩反应及美蓝(MB)、L-NAME、硝普钠(SNP)、左旋精氨酸(L-Arg)对其的影响。结果RVH大鼠离体胸主动脉环对苯肾上腺素(PHE)引起的收缩反应比对照组明显增高,去除内皮后可消除两组差异。鸟苷酸环化酶抑制剂美蓝及NO合成酶抑制剂L-NAME可使对照组收缩反应增加较RVH组明显。RVH大鼠胸主动脉环由乙酰胆碱(Ach)引起的内皮依赖性舒张反应较对照组明显减弱,而对非内皮依赖性松弛剂硝普钠(SNP)的舒张反应两组间无显著差异。NO合成底物L-Arg能显著提高RVH大鼠内皮依赖性舒张反应。结论肾血管性高血压血管内皮依赖的收缩反应增强,舒张反应减弱。其机制是血管内皮产生和释放EDRF(NO)功能受损和(或)EDRF作用减弱,合成NO的底物L-Arg不足。     

Involvement of Nitric Oxide and Potassium Channels in the Reduction of Basal Tone Produced by Blockade of Thromboxane A2/Prostaglandin H2/ Receptors in Aortic Rings Of Hypertensive Rats

This study was designed to investigate involvement of potassium channels in the action of nitric oxide facilitating reduction of basal tone by thromboxane A₂/prostaglandin H₂receptor blockade with ifetroban in rings of thoracic aorta taken from rats with aortic coarctation-induced hypertension. Ifetroban-induced reduction of basal tone in aortic rings without drug pretreatment was attenuated (P<0.05) in rings pretreated with the nitric oxide synthesis inhibitor Nω-nitro-L-arginine methyl ester (L-NAME; 3 × 10<^-4mol/L; 0.55±0.09 g versus 0.23±0.07 g). The vasorelaxing effect of ifetroban also was decreased (P<0.05) in preparations pretreated with a potassium channel blocker, either tetraethylammonium (TEA; 10^-2mol/L) or 4-aminopyridine (4-AP; 3 × 10^-3mol/L). Ifetroban-induced reduction of basal tone was not attenuated in preparations pretreated first with L-NAME and then with sodium nitroprusside (SNP; 6±1 nmol/L) to compensate for the loss of endogenous nitric oxide. However, the facilitatory effect of SNP on ifetroban-induced relaxation of aortic rings pretreated with L-NAME alone was not demonstrable in rings pretreated with L-NAME plus TEA or 4-AP. These observations suggest that a mechanism involving nitric oxide and potassium channels facilitates the reduction in basal tone produced by ifetroban in aortic rings of rats with aortic coarctation-induced hypertension     

Human monoclonal IgG anticardiolipin antibodies induce nitric oxide synthase expression

OBJECTIVE: Antiphospholipid antibodies are associated with increased risk of thrombosis, particularly as in antiphospholipid syndrome. This study aims to determine the acute effects of anticardiolipin antibodies on nitric oxide production and vascular function. METHODS: Ex vivo aortic rings from male Sprague Dawley rats were incubated with IgG monoclonal anticardiolipin antibody (IS4) or a non-specific IgG control. In organ baths, response to phenylephrine and acetlycholine was determined alone and with nitro-L-arginine methyl ester (L-NAME), 1,400 W, D-arginine, L-arginine, sodium nitroprusside and cardiolipin. In vivo antibodies were injected into anaesthetised, spontaneously breathing male Sprague Dawley rats. Haemodynamic variables and serum nitric oxide were measured. Immunohistochemistry for iNOS and eNOS was performed in kidney vessels. RESULTS: Phenylepherine contraction was decreased in the IS4 group compared to controls (p < 0.001). L-NAME, 1,400 W and cardiolipin, abolished this effect. L-Arginine caused significant relaxation in the IS4 group (p = 0.005). Mean arterial pressure in rats injected with IS4 was reduced compared to IgG and saline controls (p < 0.001). NO in plasma increased significantly after IS4 administration (p < 0.001). Immunohistochemistry showed increased iNOS expression in kidney arteries in the IS4 group, with no change in eNOS. CONCLUSION: Anticardiolipin antibodies induce NO production acutely via increased expression of iNOS in both ex vivo and in vivo models.