肿瘤坏死因子α和血管紧张素Ⅱ干预内皮细胞后细胞凋亡和诱导型一氧化氮合酶的表达

目的探讨肿瘤坏死因子α和血管紧张素Ⅱ在导致内皮细胞凋亡过程中诱导型一氧化氮合酶的表达变化及核因子κB的作用。方法核因子κB抑制剂吡咯烷二硫代氨基甲酸盐预处理和未预处理原代培养的脐静脉内皮细胞,用肿瘤坏死因子α和血管紧张素Ⅱ分别进行干预,逆转录聚合酶链反应检测诱导型一氧化氮合酶mR-NA的表达,免疫印迹法检测诱导型一氧化氮合酶和IκBα的蛋白表达,电泳迁移率分析检测核因子κB的活性,TUNEL法检测细胞凋亡。结果在10μg/L肿瘤坏死因子α和1μmol/L血管紧张素Ⅱ的干预下,核因子κB的活性显著增加(P<0.05),诱导型一氧化氮合酶mRNA和蛋白的表达与对照组比较显著增加(P<0.05),细胞凋亡发生显著增加(P<0.05);吡咯烷二硫代氨基甲酸盐抑制肿瘤坏死因子α和血管紧张素Ⅱ引起的细胞凋亡和诱导型一氧化氮合酶表达的增加。结论在肿瘤坏死因子α和血管紧张素Ⅱ作用于内皮细胞时,通过降解IκBα引起诱导型一氧化氮合酶的核转位,后者可引起诱导型一氧化氮合酶表达上调和细胞凋亡。     

罗格列酮对血管紧张素Ⅱ诱导血管平滑肌细胞血管紧张素Ⅱ受体表达的影响

目的探讨罗格列酮对血管紧张素Ⅱ诱导血管平滑肌细胞血管紧张素Ⅱ受体表达的影响及抗动脉粥样硬化可能的分子机制。方法体外培养SD大鼠血管平滑肌细胞，应用半定量逆转录聚合酶链反应和免疫组织化学技术，测定罗格列酮对血管紧张素Ⅱ诱导大鼠血管平滑肌细胞血管紧张素Ⅱ1型受体和2型受体mRNA和蛋白表达的剂量、时间依赖的影响。结果基础状态下，血管平滑肌细胞血管紧张素Ⅱ1型受体和2型受体均有少量的表达。血管紧张素Ⅱ显著上调血管紧张素Ⅱ1型受体（P〈0.01）和下调2型受体的表达（P〈0．05）。浓度依赖实验表明，不同浓度罗格列酮（20、30和50μmol／L）干预12h均显著下调血管紧张素Ⅱ1型受体mRNA和蛋白的表达（P〈0．01），上调2型受体mRNA和蛋白的表达（P〈0．01和0．05）。时间依赖实验表明，30μmol／L的罗格列酮干预后，6h即出现明显的干预效应，24h时下调血管紧张素Ⅱ1型受体和上调2型受体mRNA和蛋白的作用最大，与血管紧张素Ⅱ组比差异有显著性（P〈0．01）。结论罗格列酮可呈浓度依赖和时间依赖性地下调血管紧张素Ⅱ诱导的大鼠血管平滑肌细胞血管紧张素Ⅱ1型受体mRNA和蛋白的表达，上调血管紧张素Ⅱ2型受体mRNA和蛋白的表达，这可能是过氧化体增殖物激活型受体7激动剂罗格列酮发挥抗炎、抗动脉粥样硬化作用的重要机制。     

血管紧张素Ⅱ介导的大鼠血管平滑肌细胞STAT1激活与核转位

目的 检测血管紧张素Ⅱ（AngⅡ）介导的大鼠血管平滑肌细胞（VSMC）增殖过程中信号转导和转录活化因子-1（STAT1）的激活与核转位。方法 本文采用Western印迹、非同位素凝胶电泳（EMSA）和免疫荧光染色的方法，观察AngⅡ刺激大鼠主动脉VSMC前后，细胞中STAT1的活化状态与定位。结果 VSMC经AngⅡ干预后，胞内磷酸化的STAT1（P-STAT1）蛋白表达增加（P〈0．01），达峰后随时间梯度逐渐下降，AngⅡ干预15min后检测到胞核内有蛋白．DNA复合物形成。这一反应可被血管紧张素Ⅱ1型受体（AT1）阻滞剂Losartan以及Jak2抑制剂AC-490抑制（P〈0．01）。免疫荧光染色结果也显示AngⅡ干预后P-STAT1主要在胞核内表达。结论AngⅡ可以通过和AT1受体结合，激活Jak／STAT通路，在AngⅡ介导的大鼠VSMC增殖过程中发挥作用。     

阿托伐他汀抑制心肌细胞肥大并增强过氧化体增殖物激活型受体β/δ的表达

目的探讨阿托伐他汀在体外对血管紧张素Ⅱ介导的肥大心肌细胞的作用，分析过氧化物酶体增殖物激活型受体β／δ在其中的可能作用。方法采用体外原代培养新生大鼠的心室肌细胞方法，用血管紧张素Ⅱ诱导建立心肌肥厚模型，在模型中加入不同浓度的阿托伐他汀，通过数码相机摄影扫描，以测量软件NIH Image J测定分析心肌细胞表面积，利用氚标亮氨酸掺入方法检测心肌细胞蛋白合成速率及使用逆转录聚合酶链反应半定量测定心房钠尿肽、脑钠尿肽和过氧化体增殖物激活型受体β／δ mRNA的表达变化。结果血管紧张素Ⅱ可使体外培养的心肌细胞表面积（P〈0．01）和氚标亮氨酸的掺入增加（P〈0．01），升高心房钠尿肽和脑钠尿肽（均为P〈0．01）的表达．过氧化体增殖物激活型受体β／δ（P〈0．01）表达下降；阿托伐他汀可逆转上述变化并呈剂量依赖性（P〈0．05）。而作为溶剂的二甲亚砜对心肌肥厚无影响（P〉0．05）。结论阿托伐他汀具有抑制血管紧张素Ⅱ介导的体外心肌细胞肥大的作用，过氧化体增殖物激活型受体β／δ很可能参与该过程。     

急性心肌梗死大鼠心脏一氧化氮合酶表达的改变

目的 通过建立大鼠心肌梗死模型，观察急性心肌梗死对大鼠心脏内皮型一氧化氮合酶mRNA和诱导型一氧化氮合酶蛋白表达的影响。方法48只健康成年SD大鼠（体重200～250g）随机分为假手术组和缺血组，取1、2、8和24h四个不同时间点观察。采用开胸结扎冠状动脉左前降支建立心肌缺血模型，逆转录聚合酶链反应检测大鼠心肌梗死后1、2及24h三个时段缺血心肌内皮型一氧化氮合酶mRNA的表达；免疫组织化学染色检测冠状动脉结扎后8h缺血心肌诱导型一氧化氮合酶蛋白的表达。结果冠状动脉结扎后2h，缺血组大鼠缺血心肌组织内皮型一氧化氮合酶mRNA表达下降（P〈0．05），并持续至结扎后24h；结扎后24h组内皮型一氧化氮mRNA的表达与结扎后2h组相比无显著性差异（P〉0．05）。冠状动脉结扎后8h，梗死区存活心肌组织细胞诱导型一氧化氮合酶蛋白大量表达，而假手术组未见诱导型一氧化氮合酶蛋白表达。结论正常大鼠心肌组织有内皮型一氧化氮合酶基因表达，无诱导型一氧化氮合酶蛋白表达。在心肌梗死早期缺血心肌内皮型一氧化氮合酶mRNA表达减少。心肌急性缺血刺激早期诱导大鼠缺血心肌组织诱导型一氧化氮合酶蛋白大量表达。     

氧化剂对RAW264.7细胞诱导型一氧化氮合酶基因表达的影响

为揭示氧化应激对巨噬细胞诱导型一氧化氮合酶基因表达的影响 ,采用逆转录多聚酶链反应技术 ,观察氧化剂叔丁基氢过氧化物对RAW 2 64.7细胞诱导型一氧化氮合酶mRNA表达的影响。结果发现 ,1.5× 10 -4mol/L叔丁基氢过氧化物能够诱导RAW 2 64.7细胞诱导型一氧化氮合酶mRNA表达 ,放线菌素D、环己酰亚胺及acetovanilone均可减弱叔丁基氢过氧化物对RAW2 64.7细胞诱导型一氧化氮合酶表达的诱导。另外 ,叔丁基氢过氧化物对RAW 2 64.7细胞诱导型一氧化氮合酶表达的诱导作用还可被核因子 κB抑制剂PDTC减弱。可见 ,氧化剂可诱导RAW 2 4.7细胞诱导型一氧化氮合酶mRNA的表达 ,且作用在转录水平 ,该过程中有新的蛋白质合成及内源性活性氧产生的参与 ,转录因子核因子 κB的激活也可能与该诱导过程有关     

白蛋白对肾小管上皮细胞血管紧张素转换酶2表达的抑制作用

目的观察白蛋白对人近端肾小管上皮细胞株（HK_2）血管紧张素转换酶2（ACE2）mRNA和蛋白表达的影响,探讨蛋白尿激活肾脏局部RAs的机制。方法采用不同浓度的牛血清白蛋白（BSA）作用HK-2细胞不同时间。以实时RT-PCR和Western印迹检测ACE2mRNA和蛋白的表达。采用放射免疫法检测细胞上清液中血管紧张素Ⅱ（ATⅡ）含量。采用激光共聚焦显微镜观察ACE2蛋白的表达。结果与对照组（相对表达量为O）相比,BSA使ACE2mRNA表达显著减少（2．5mg／ml：-1．05土0．12;5mg／ml：-1．30±0．11;10mg／ml：-2．54土0．44;P均〈0．05）。同时,BSA使ACE2蛋白表达显著降低（对照组：0．90±0．10;2．5mg／ml：0．66士0．09;5mg／ml：0．50士0．07;10mg／ml：0．35±0．05;P均〈0．05）。其中BSA（10mg／ml）使ACE2mRNA及蛋白表达减少呈时间依赖性（P均〈0．05）。与对照组相比,不同浓度BSA组的细胞上清液中的ATⅡ均显著升高（P均〈0．05）。激光共聚焦显微镜可见ACE2主要分布于细胞膜。结论BSA可显著抑制HK-2细胞ACE2 mRNA和蛋白的表达,此作用所导致的近曲小管间质液ATⅡ浓度升高可能与间质纤维化相关。     

甲状腺乳头状癌组织中ANG-Ⅱ、AT1R、VEGF表达及意义

目的探讨甲状腺乳头状癌（PTC）的发生机制。方法采用免疫组化SP法检测20例PTC（PTC组）、20例甲状腺良性病变（良性组）和15例正常甲状腺（对照组）组织标本中血管紧张素Ⅱ（ANG-Ⅱ）及其受体1（AT1R）和血管内皮生长因子（VEGF）蛋白的表达。结果ANG-Ⅱ、ATIR、VEGF阳性率PTC组明显高于良性组和对照组（P〈0．05）,良性组高于对照组（P〈0．05）;PTC组织中ANG-Ⅱ、AT1R与VEGF蛋白表达呈显著正相关（r=0．594,P〈0．01;r=0．446,P〈0．05）。结论ANG-Ⅱ、AT1R高表达促进了PTC的发生,其机制可能为诱导VEGF产生,促进肿瘤新生血管形成。     

心房颤动患者心房组织血管紧张素Ⅱ受体表达的研究

目的 探讨心房颤动（房颤）患者心房组织血管紧张素Ⅱ受体（AT－R）基因转录和蛋白质表达的变化。方法 33例风湿性心脏瓣膜病患者，心脏外科手术时取右心耳组织。通过逆转录－聚合酶链反应和免疫组织化学，测量血管紧张素Ⅱ受体1（AT1－R)的血管紧张素Ⅱ受体2（AT2－R）的mRNA和蛋白的相对表达量。结果 窦性心律患者、阵发性房颤及慢性房颤患者之间的心房组织AT1－R手AT2－R的mRNA水平差别均无显著性（P均＞0．05）；AT1－R和AT2－R在各组患者心房组织中主要表达在心房肌细胞；与窦性心律患者相比，阵发性房颤和慢性房颤患者的心房组织AT1－R的蛋白表达均明显减少（P＜0．05；P＜0．01），而AT2－R的蛋白表达均明显增高（P＜0．01；P＜0．05）。结论 心房在房颤时AT1－R表达下调而AT2－R表达上调，提示血管紧张素系统参与了房颤的心房结构重构。     

血管紧张素Ⅱ介导高糖诱导的人主动脉内皮细胞转分化

目的探讨高糖对内皮细胞转分化的影响及其与血管紧张素Ⅱ（ATⅡ）的关系。方法将人主动脉内皮细胞分成正常浓度葡萄糖（NG）组、高糖（HG）组和厄贝沙坦干预（HG＋Irb）组。放射免疫法检测细胞上清液中ATⅡ的浓度。共聚焦显微镜观察CD31和成纤维细胞特异蛋白1（FSP1）的双染色结果。Western blot检测FSP1蛋白水平的表达。结果与NG组比,高糖刺激的内皮细胞导致ATⅡ和FSP1表达增加（P〈0．05）,呈浓度和时间依赖性。共聚焦显微镜可见CD31和FSPl表达重叠,且一些细胞获得纺锤样的改变并失去CD31染色。厄贝沙坦可抑制高糖引起的上述改变（P〈0．05）。结论高糖可能通过ATⅡ介导的内皮细胞转分化导致内皮细胞损伤,而厄贝沙坦抑制内皮细胞转分化。     

Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release

This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.     

Protective mechanisms of the angiotensin II type 1 receptor blocker candesartan against cerebral ischemia: in-vivo and in-vitro studies

BACKGROUND: Angiotensin II type 1 (AT1) receptor blockers decrease ischemia by mechanisms dependent on and independent of arterial blood pressure in hypertensive rats and AT1-R knockout mice, respectively. However, the detailed mechanisms underlying the effects of AT1 receptor blockers remain unclear. AIMS: To elucidate the systemic and focal effects of AT1 receptor blockers against cerebral ischemia in in-vivo and in-vitro studies. METHODS: Normotensive Wistar rats were treated for 2 weeks with 0.5 or 1 mg/kg candesartan cilexetil and then subjected to 2-h middle cerebral artery occlusion-reperfusion. Human umbilical endothelial cells were stimulated with the active form of candesartan and angiotensin II in the absence and presence of an angiotensin II type 2 (AT2) receptor antagonist. RESULTS: In candesartan-pretreated hypotensive and nonhypotensive rats, blood pressure was moderately increased during middle cerebral artery occlusion and fell gradually to the baseline after the reperfusion; it remained elevated in the control even after the reperfusion occlusion. Candesartan treatment resulted in a decrease in the cortical infarct volume and oxidative damage, the hypoxic status was improved, and the expression of repair-associated and growth-associated proteins in the cortical penumbra was augmented. Candesartan also increased the eNOS mRNA level and the lumen size of the middle cerebral artery. In human umbilical endothelial cells, candesartan increased the eNOS protein level AT2-R dependently, inhibited the expression of nicotinamide adenine dinucleotide phosphate oxidase subunits and angiotensin II-induced intracellular reactive oxygen species and nitric oxide, and promoted the extracellular release of nitric oxide, suggesting that it augmented the bioavailability of nitric oxide. CONCLUSION: Among the mechanisms candesartan exerts in its protection against cerebral ischemia, restoration of endothelial function may represent an attractive therapeutic goal to address cerebral ischemia.     

Modulation of constitutive nitric oxide synthase, bcl-2 and Fas expression in cultured human coronary endothelial cells exposed to anoxia-reoxygenation and angiotensin II: role of AT1 receptor activation.

BACKGROUND: Angiotensin II (Ang II) plays a critical role in the pathophysiology of myocardial ischemia-reperfusion injury. We have recently shown that reoxygenation following a period of anoxia causes apoptosis of cultured human coronary artery endothelial cells (HCAECs). Ang II further enhances apoptosis of HCAECs via Ang II type 1 receptor (AT1R) activation. Recent studies suggest an important role of constitutive nitric oxide synthase (cNOS), Fas and bcl-2 proteins in apoptosis. This study was designed to examine the modulation of cNOS, and Fas and bcl-2 expression in HCAECs during exposure to anoxia-reoxygenation and Ang II. METHODS AND RESULTS: HCAECs were exposed to anoxia-reoxygenation and Ang II. Anoxia-reoxygenation significantly decreased cNOS mRNA, protein and activity in cultured HCAECs (P < 0.05 vs. control). Anoxia-reoxygenation also caused an increase in Fas and a decrease in bcl-2 protein expression in cultured HCAECs (both P < 0.05 vs. control). The presence of Ang II (0.3 microM) further enhanced these effects of anoxia-reoxygenation on cNOS, Fas and bcl-2 expression. The effects of Ang II were significantly attenuated by the AT1R inhibitor losartan (10 microM). CONCLUSION: During exposure of HCAECs to anoxia-reoxygenation and Ang II, AT1R activation induces important changes in cNOS mRNA, protein expression and activity, as well as bcl-2 and Fas protein expression which may have a bearing on the development of apoptosis.     

Angiotensin II/AT2 receptor-induced vasodilation in stroke-prone spontaneously hypertensive rats involves nitric oxide and cGMP-dependent protein kinase

BACKGROUND: Angiotensin II (Ang II) induces vasodilation, in part, through angiotensin type 2 receptor (AT2R)-induced actions in conditions associated with angiotensin type 1 receptor (AT1R) blockade and AT2R upregulation. Ang II/AT2R-induced vasodilation involves nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-dependent processes. We previously demonstrated that AT2R-mediated effects involve inhibition of the RhoA/Rho kinase pathway. However, molecular mechanisms underlying this phenomenon are unknown. AIMS: In the present in-vivo study we tested the hypothesis that AT2R-elicited vasodilation is associated with nitric oxide synthase (NOS) activation and NO production, and that a cGMP-dependent protein kinase (cGKI), which inactivates RhoA, is upregulated when stroke-prone spontaneously hypertensive rats (SHRSP) are treated with AT1R blockers. METHODS: SHRSP and Wistar-Kyoto (WKY) rats were treated with the AT1R blocker valsartan for 14 days. Dilatory responses to Ang II with or without the NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) were performed in norepinephrine-precontracted vessels in the presence of valsartan. Expression of AT2R, endothelial NOS (eNOS) and cGKI was assessed by immunoblotting. NO bioavailability and NAD(P)H oxidase activity were evaluated by chemiluminescence. RESULTS: Ang II elicited vasodilation in valsartan-treated SHRSP. L-NAME inhibited this effect, indicating a role for NO. eNOS expression and NO concentration were increased twofold by valsartan, only in SHRSP. Expression of cGKI was reduced in SHRSP and restored after valsartan treatment. NAD(P)H oxidase activity was approximately threefold higher in SHRSP versus WKY (P < 0.05) and reduced by valsartan. CONCLUSIONS: Ang II, via AT2R, facilitates vasodilation through NOS/NO-mediated pathways and upregulation [corrected] of CGK1 [corrected] after chronic AT1R antagonism. These effects may contribute in part to beneficial actions of AT1R blockers in the treatment of hypertension.     

Role of the angiotensin AT(1) receptor in rat aortic and cardiac PAI-1 gene expression

Although the renin-angiotensin system has been implicated in increasing plasminogen activator inhibitor-1 (PAI-1) expression, the role of the angiotensin type 1 (AT(1)) receptor is controversial. This report examines the effects of angiotensin peptides, angiotensin-converting enzyme inhibition, and AT(1) antagonism on rat aortic and cardiac PAI-1 gene expression. In vitro, angiotensin (Ang) I, Ang II, and angiotensin Arg(2)-Phe(8) (Ang III) were potent agonists of PAI-1 mRNA expression in rat aortic smooth muscle cells (RASMCs), and stimulation of PAI-1 by these peptides was blocked by the AT(1) antagonist candesartan. Angiotensin Val(3)-Phe(8) (Ang IV) and angiotensin Asp(1)-Pro(7) (Ang [1-7]) did not affect PAI-1 expression in RASMCs. In neonatal rat cardiomyocytes, Ang II increased PAI-1 mRNA expression by 4-fold (P<0.01), and this response was completely blocked by AT(1) receptor antagonism. Continuous intrajugular infusion of Ang II into Sprague-Dawley rats for 3 hours increased aortic and cardiac PAI-1 mRNA expression by 17- and 9 fold, respectively, and these Ang II responses were completely blocked by coinfusion with candesartan. Aortic and cardiac PAI-1 expressions were compared in spontaneously hypertensive rats and Wistar-Kyoto rats. PAI-1 expression in the aorta and heart from spontaneously hypertensive rats was 5.8-fold and 2-fold higher, respectively, than in control Wistar-Kyoto rats (P<0.05). Candesartan treatment for 1 week reduced aortic and cardiac PAI-1 expression in spontaneously hypertensive rats by 94% and 72%, respectively (P<0.05), but did not affect vascular PAI-1 levels in Wistar-Kyoto rats. These results demonstrate a role for the AT(1) receptor in mediating the effects of Ang II on aortic and cardiac PAI-1 gene expression.     

鼠双微基因2在血管紧张素Ⅱ和神经酰胺致内皮细胞凋亡中作用的实验研究

目的探讨神经酰胺和血管紧张素Ⅱ（AngⅡ）致内皮细胞凋亡过程中鼠双微基因2（mdm2）的变化及其作用。方法体外培养脐静脉内皮细胞,分别用AngⅡ1型受体拮抗剂氯沙坦、AngⅡ2型受体拮抗剂PDl23319、神经酰胺合成酶抑制剂烟曲霉素B1（FB1）预处理细胞,再加入AngⅡ与双蒸水对照组比较观察细胞凋亡情况及mdm2 mRNA和蛋白的表达,并用不同浓度的c2-神经酰胺进行处理,RT—PCR和Western blot检测mdm2的mRNA和蛋白表达及细胞凋亡的情况。结果PD123319组和FB1组抑制了AngⅡ诱导的内皮细胞凋亡,其凋亡指数明显下降（P〈0．05）,而与对照组相比差异无统计学意义,相反氯沙坦组凋亡指数较对照组显著增加（P〈0．05）,FB1组抑制了mdm2的表达。c2．神经酰胺呈剂量依赖性诱导内皮细胞凋亡,mdm2的表达随着C2-神经酰胺浓度的增加呈现降低的趋势。结论AngⅡ诱导内皮细胞凋亡通过AT2受体和神经酰胺起作用,AngⅡ和神经酰胺可能是通过抑制mdm2来诱导凋亡的。     

Effects of quinapril on expression of eNOS,ACE, and AT1 receptor in deoxycorticosterone acetate-salt hypertensive rats

Angiotensin II and nitric oxide (NO) may play a role in hypertensive cardiovascular remodeling. We evaluated the effects of long-term treatment with quinapril, an angiotensin converting enzyme (ACE) inhibitor, on expression of endothelial NO synthase (eNOS), ACE, and angiotensin II type 1 (AT1) receptor in the left ventricle and evaluated these relations to myocardial remodeling in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Deoxycorticosterone acetate-salt rats were induced with weekly injections of DOCA (30 mg/kg) and 1% saline in drinking water after right nephrectomy. Quinapril (DOCA-QUI, 10 mg/kg/day, subdepressor dose) or AT1 receptor antagonist TCV-116 (DOCA-TCV, 5 mg/kg/day, subdepressor dose) or vehicle (DOCA-V) were given after induction of DOCA-salt hypertension for 5 weeks, and age-matched sham-operated rats (ShC) served as a control group. The eNOS expression in the left ventricle were significantly decreased in DOCA-V compared with ShC, and were significantly increased in DOCA-QUI and DOCA-TCV compared with ShC and DOCA-V. The gene expression of ACE, AT1 receptor, and type I collagen mRNA were significantly increased in DOCA-V compared with ShC, and significantly suppressed in DOCA-QUI compared with DOCA-V. The DOCA-V rats demonstrated a significant increase of the wall-to-lumen ratio, perivascular fibrosis, and myocardial fibrosis, with all these parameters being significantly improved by quinapril. Myocardial remodeling in DOCA-salt hypertensive rats was significantly ameliorated by a subdepressor dose of quinapril, which may be due to an increase in eNOS mRNA and protein expression and a decrease in ACE and AT1 receptor mRNA expression in the left ventricle.     

Chronic angiotensin IV treatment reverses endothelial dysfunction in ApoE-deficient mice

AIMS: Endothelial dysfunction is considered a surrogate marker for cardiovascular disease. Angiotensin II, the principal hormone of the renin angiotensin system, is known to promote atherogenesis. However, other angiotensin peptide fragments such as angiotensin IV possess biological activity that may in fact counter-regulate the actions of angiotensin II. Therefore, we investigated the role of angiotensin IV on the development of endothelial dysfunction in apolipoprotein E-deficient (ApoE-/-) mice. METHODS AND RESULTS: In contrast to their wild-type control, ApoE-/- mice that were fed a high-fat diet had exacerbated endothelial dysfunction, evidenced by impaired endothelium-dependent vasodilation. Chronic infusion of angiotensin IV (1.44 mg/kg per day) in ApoE-/- mice for 2 weeks resulted in significant improvements in endothelial function. Angiotensin IV treatment markedly decreased superoxide levels (dihydroethidium staining fluorescence and L-012 chemiluminescence) and increased endothelial nitric oxide synthase expression (immunoreactivity and western blotting) in aortic tissue. Co-treatment of angiotensin IV with either AT4 receptor antagonist divalinal-Ang IV or AT2 receptor antagonist PD123319 attenuated these changes, indicating involvement of both the AT4 and the AT2 receptors. CONCLUSION: Chronic angiotensin IV treatment in ApoE-/- mice evoked a marked vasoprotective effect that appeared to be mediated by improved NO bioavailability as a result of AT4 and/or AT2 receptor stimulation.     

Simvastatin treatment in subjects at high cardiovascular risk modulates AT1R expression on circulating monocytes and T lymphocytes

OBJECTIVE: Angiotensin II, through the activation of angiotensin II type 1 receptors, plays a crucial role in atherosclerosis. Statins may interfere with the effects of angiotensin II. METHODS: We have investigated the expression of angiotensin II type 1 receptor, angiotensin II type 2 receptor and angiotensinogen on circulating monocytes and T-lymphocytes from subjects at high risk for vascular events before and during simvastatin treatment, and healthy controls. In-vitro experiments were also performed to assess the ability of simvastatin to interfere with angiotensin II signalling. RESULTS: In comparison with controls, high-risk subjects had similar angiotensin II type 1 receptor expression on the cell membranes but significantly higher angiotensin II type 1 receptor mRNA levels at least in monocyte subsets whereas their expression on T cells was similar. Angiotensin II type 2 receptor mRNA expression was higher than controls in both monocytes and T lymphocytes. No differences were observed in angiotensinogen expression on monocytes while T lymphocytes of high-risk subjects show higher expression. One-month treatment of high-risk subjects with simvastatin resulted in a reduction of angiotensin II type 1 receptor mRNA without affecting angiotensin II type 2 receptor whereas angiotensinogen mRNA expression was reduced at least in monocytes. Incubation in vitro with simvastatin reduces the expression of angiotensin II type 1 receptor mRNA levels on monocytes from untreated subjects. CONCLUSION: Simvastatin induces down-regulation of the angiotensin II type 1 receptor, interferes with angiotensin II activity in immune cells and contributes to the anti-inflammatory profile of statins that can explain the therapeutic effects of these drugs.