血管紧张素Ⅱ受体在人扩张皮肤中的表达及意义

目的：观察血管紧张素Ⅱ（Angiotensin Ⅱ，Ang Ⅱ）1型（Ang Ⅱ type 1，AT 1）受体和2型（Ang Ⅱ type2，AT2）受体蛋白和基因以及血管紧张素原（Angiotensinogen，AGT）基因在人扩张后皮肤和正常皮肤组织中表达的变化。方法：采用常规病理学技术和免疫组织化学方法检测扩张与未扩张皮肤组织的病理特征以及AT1和AT2受体表达的变化，提取扩张与未扩张皮肤组织的总RNA后，用逆转录一多聚酶链式反应法（RT-PCR法）对AGT及AT1和AT2受体在扩张与未扩张皮肤组织中基因的表达变化进行观察。结果：在正常皮肤和扩张后皮肤组织中AT1和AT2受体蛋白和mRNA均有表达。在扩张后皮肤中ATI受体蛋白和mRNA表达显著增加，与正常皮肤组织中的mRNA表达量相比增加约3倍（足0．05vs正常皮肤）；而AT2受体蛋白和mRNA表达仅有轻度增加，且差异并不显著（p0．05vs正常皮肤）。和ATI受体基因表达的变化趋势类似，AGT mRNA也在扩张后皮肤中表达显著增强，约是正常皮肤的4倍（只0、05vs正常皮肤）。结论：在皮肤扩张过程中血管紧张素系统被激活，AngⅡ受体AT1表达增加，AngⅡ可能通过AT1受体参与扩张后皮肤组织的病理改变。     

增生性瘢痕中血管紧张素原和血管紧张素Ⅱ受体基因的表达

目的观察血管紧张素原(AGT)及血管紧张素Ⅱ(AngⅡ)的1型受体(AT1)和2型受体(AT2)在人增生性瘢痕和正常皮肤中基因的表达。方法将增生性瘢痕皮肤的标本分为增生期和成熟期两组,并提取正常皮肤和增生性瘢痕中的总RNA,用逆转录-多聚酶链式反应(RT-PCR)法,对AGT及AT1和AT2在增生性瘢痕中的基因表达进行病理学检测和观察。结果在正常皮肤和增生性瘢痕中AT1和AT2基因mRNA均有表达。在增生期增生性瘢痕中AT1和AT2基因mRNA的表达增加,与正常皮肤中的表达相比差异有显著意义(P<0.05);而在成熟期增生性瘢痕中AT1和AT2基因mRNA的表达减弱。与AngⅡ受体基因的表达相类似;AGT在增生期增生性瘢痕中的表达增加,在成熟期增生性瘢痕中的表达减弱。结论在增生性瘢痕形成过程中血管紧张素系统被激活,AngⅡ的AT1和AT2的基因表达增加,AngⅡ可能通过AT1和AT2调节增生性瘢痕的发生和成熟。     

血管紧张素II受体在皮肤附件中的表达研究

目的:观察血管紧张素II(AngiotensinII,AngII)1型(AngIItype1,AT1)受体和2型(AngIItype2,AT2)受体在人正常皮肤毛囊、汗腺、皮脂腺中的表达和分布,探索其可能的生物学意义。方法:用免疫组织化学方法和常规病理学技术检测AT1和AT2受体在13例正常皮肤附件中的表达和分布。结果:在所检测的13例标本的皮肤附件中AT1和AT2受体都有表达。在汗腺,皮脂腺,AT1和AT2受体在腺上皮细胞有较强阳性染色信号。在毛囊中,AT1和AT2受体在外根鞘、内根鞘上皮细胞中表达较强,但在毛乳头未见阳性染色信号。结论:AngII受体AT1和AT2在皮肤附件中表达和分布提示,AngII可能通过AT1和AT2受体参与毛囊、汗腺、皮脂腺的发生、生长和损伤后再生,进一步研究AT1和AT2受体在这个过程中的作用将有助于理解皮肤附件疾病的发生机制,改善深度创面愈合的效果。     

增生性瘢痕中血管紧张素原和血管紧张素Ⅱ受体基因的表达

目的观察血管紧张素原（AGT）及血管紧张素Ⅱ（Ang Ⅱ）的1型受体（AT1）和2型受体（AT2）在人增生性瘢痕和正常皮肤中基因的表达。方法将增生性瘢痕皮肤的标本分为增生期和成熟期两组，并提取正常皮肤和增生性瘢痕中的总RNA，用逆转录-多聚酶链式反应（RT—PCR）法，对AGT及AT1和AT2在增生性瘢痕中的基因表达进行病理学检测和观察。结果在正常皮肤和增生性瘢痕中AT1和AT2基因mRNA均有表达。在增生期增生性瘢痕中AT1和AT2基因mRNA的表达增加，与正常皮肤中的表达相比差异有显著意义（P〈0．05）；而在成熟期增生性瘢痕中AT1和AT2基因mRNA的表达减弱。与AngⅡ受体基因的表达相类似；AGT在增生期增生性瘢痕中的表达增加，在成熟期增生性瘢痕中的表达减弱。结论在增生性瘢痕形成过程中血管紧张素系统被激活，AngⅡ的AT1和AT2的基因表达增加，AngⅡ可能通过AT1和AT2调节增生性瘢痕的发生和成熟。     

血管紧张素Ⅱ受体在皮肤血管瘤不同时期的表达

目的：观察血管紧张素Ⅱ 1型受体（AT1）和2型受体（AT2）在毛细血管瘤组织中的表达，探讨血管紧张素Ⅱ与毛细血管瘤发生、发展及自然消退可能的关系.方法：采用免疫组织化学的方法检测AT1和AT2受体在29例毛细血管瘤和9例正常皮肤组织中的表达和分布规律.结果：在增生期毛细血管瘤组织中扩张的微血管内皮细胞仅见AT1受体表达，未见AT2受体表达.在消退期毛细血管瘤组织中扩张的微血管内皮细胞可同时检测到AT1和AT2受体阳性染色信号.结论：血管紧张素Ⅱ可能通过AT1和AT2受体参与血管瘤的发生、发展及自然消退。     

血管紧张素转化酶和血管紧张素Ⅱ受体在银屑病患者皮损中的表达

目的:观察血管紧张素转化酶(ACE)、血管紧张素Ⅱ1型(AT1)和2型(AT2)受体在银屑病患者皮损和非皮损以及正常皮肤中的表达特征,探讨血管紧张素系统与银屑病发病机制中表皮角质形成细胞过度增殖和异常角化的关系。方法:用免疫荧光组织化学方法和常规病理技术检测ACE、AT1和AT2受体在12例银屑病患者典型皮损和非皮损以及5例正常皮肤组织中的表达和分布规律。结果:在正常皮肤组织,ACE的表达主要定位于表皮基底层角质形成细胞,AT1和AT2受体在整个表皮层均有阳性表达,但荧光信号较弱。在银屑病患者非皮损处,ACE、AT1和AT2受体的表达与正常皮肤相似。在银屑病皮损中的表皮层角质形成细胞ACE表达明显增加,整个表皮层均可见较强绿荧光颗粒,真皮浅层成纤维细胞亦可见绿色荧光颗粒。和ACE的表达变化类似,在银屑病皮损中AT1和AT2受体表达也明显增加,表皮全层可见分布密集的荧光颗粒,真皮浅层成纤维细胞也可见荧光颗粒。结论:在银屑病患者皮损处肾素-血管紧张素系统(RAS)被激活,AngⅡ产生和其受体表达增加,AngⅡ可能通过其受体参与银屑病患者皮损处角质形成细胞的过度增殖角化不全的组织学改变。     

血管紧张素II及其受体在人卵巢的表达

目的　探讨卵巢血管紧张素II(AngII)及其受体 (AT1、AT2 )在人卵巢的表达与分布。　方法　免疫组化法检测33份人卵巢组织标本中AngII及其受体AT1、AT2的表达与分布。　结果　AngII及受体AT1、AT2在卵巢的分布基本一致 ,三者在卵母细胞均有表达 ,大卵泡尤其是排卵前卵泡的颗粒细胞含量丰富 ,卵泡膜细胞几无表达 ;颗粒黄体细胞与膜黄体细胞三者含量均丰富 ,并伴随黄体退化而消失。　结论　AngII及其受体可在人卵巢局部生成 ,并存在于同一种细胞内 ,提示它们可能以自分泌方式参与卵巢功能的调节。     

血管紧张素Ⅱ受体在胰腺纤维化大鼠胰腺组织中的表达及其意义

目的动态观察血管紧张素II受体在胰腺纤维化大鼠胰腺组织中的表达并探讨其可能意义。方法采用胰管内注射2%三硝基苯磺酸(TNBS)诱导大鼠胰腺纤维化模型。制模后第3、21、28、35、42、49天分别处死大鼠,每组6只大鼠。对照组仅行剖腹术而未注射TNBS。应用VanGieson(V-G)染色观察胰腺组织纤维化程度。免疫组化和RT-PCR检测胰腺组织AT1蛋白、血管紧张素II受体mRNA和TNF-αmRNA表达。结果模型组大鼠胰腺组织细胞外基质合成较对照组明显增加。胰腺组织TNF-αmRNA表达逐渐增加并于第五周达峰值。AT1、AT2mRNA表达随时间不同呈不同程度的增加,分别于第28天、第35天达到峰值(382%和314%)。与AT1B受体mRNA相比,AT1受体亚型AT1AmRNA表达水平升高更为明显。免疫组化结果提示,模型组大鼠胰腺组织AT1蛋白表达增加并主要分布于纤维化区域。结论血管紧张素II可能通过AT1、AT2介导的途径参与了TNBS诱导的大鼠胰腺组织纤维化形成过程。     

介导血管紧张素Ⅱ上调近端肾小管上皮细胞金属蛋白酶组织抑制剂1表达的信号分子研究

目的 研究信号转导子和转录激活子(STAT)在血管紧张素Ⅱ(AngⅡ)诱导人近端肾小管上皮细胞系HK-2细胞表达基质金属蛋白酶组织抑制剂1(TIMP-1)过程中的作用。方法 采用凝胶阻滞电泳(EMSA)测定DNA-STAT结合活性变化。Supershift和Western印迹分析STAT蛋白的组成。激光扫描共聚焦显微镜观察活化STAT蛋白的核转位。采用RT-PCR方法检测HK-2细胞AT1和AT2受体的表达。Northern印迹检测TIMP-1的mRNA表达。结果 AngⅡ能够以剂量和时间依赖方式激活STAT1和STAT3。AngⅡ刺激后TIMP-1 mRNA的表达显著增加。HK-2细胞可表达AT1和AT2两种受体。AngⅡ激活STAT蛋白和上调TIMP-1的作用能被AT1受体拮抗剂阻断，而不能被AT2受体拮抗剂阻断。结论 AngⅡ通过激活近端肾小管上皮细胞的AT1受体来活化STAT1和STAT3信号分子，并可以进而上调TIMP-1的mRNA表达。     

人增生性瘢痕中血管紧张素Ⅱ受体表达的研究

目的观察血管紧张素Ⅱ（AngⅡ）1型受体（AT1）和2型受体（AT2）在人增生性瘢痕和正常皮肤中的表达特征及其对瘢痕形成的影响。方法用免疫组织化学方法和常规病理技术检测AT1和AT2受体在18例增生性瘢痕和7例正常皮肤组织中的表达和分布规律。结果在正常皮肤中，AT1和AT2受体主要分布于表皮角质形成细胞的胞膜、真皮毛细血管。在生长活跃的增生性瘢痕组织中，AT1和AT2受体表达增强（P〈0．05），成纤维细胞亦可见较强的阳性染色信号。随瘢痕逐渐成熟AT1和AT2受体表达逐渐减弱，但仍高于正常皮肤（P〈0．05）。结论AngⅡ可能通过AT1和AT2受体参与增生性瘢痕的形成，深入研究AT1和AT2受体在这个过程中的作用将有助于理解增生性瘢痕形成的机制。     

Tubular expression of angiotensin II receptors and their regulation in IgA nephropathy

Enhanced renal expression for the renin-angiotensin system (RAS) is detected in IgA nephropathy (IgAN). Previous data showed an altered glomerular expression of angiotensin II type 1 receptor (AT1R), suggesting a regulatory response to high intrarenal angiotensin II (Ang II) concentration in IgAN. In this study, the expression and regulation of Ang II receptors were examined in human proximal tubular epithelial cells (PTEC) in IgAN. Tubular expression of AT1R and Ang II type 2 receptor (AT2R) was increased in IgAN. In vitro culture experiment showed that the upregulation of Ang II receptors was not due to the direct effect of IgA but the indirect effect after IgA deposition on human mesangial cell. When PTEC were cultured with conditioned culture medium from human mesangial cells activated with IgA, Ang II production was upregulated, leading to inflammation and apoptosis via the AT1R and AT2R, respectively. Sequential expression of Ang II receptors determined the injury of PTEC induced by mediators in the conditioned medium. The initial interaction between Ang II and AT1R activated both protein kinase C and mitogen-activated protein kinase pathways, leading to inflammatory responses. This early AT1R-dependent event was followed by upregulation of AT2R expression and continued Ang II release. The interaction between Ang II and AT2R subsequently led to expression of cleaved poly[ADP-ribose] polymerase through downregulation of the mitogen-activated protein kinase pathway. The data suggest that appropriate control of Ang II receptor activities in PTEC may ameliorate tubulointerstitial injury in IgAN.     

Angiotensin II activates nuclear transcription factor-kappaB through AT1 and AT2 receptors

BACKGROUND: Recent evidence suggests that angiotensin II (Ang II) induces a variety of proinflammatory mediators including chemokines. Nuclear factor-kappaB (NF-kappaB) activation plays an important role in Ang II-mediated inflammation. The present study investigated which Ang II receptor subtype is involved in NF-kappaB activation. We focused particularly on the Ang II subtype 2 (AT2) receptor because we previously observed that Ang II-induction of the chemokine RANTES in vitro and in vivo is mediated through AT2 receptors.METHODS: AT1 or AT2 receptors were selectively overexpressed in COS7 cells that normally do not express Ang II receptors. In addition, rat glomerular endothelial cells (GER) that express AT1 and AT2 receptors and PC12 cells that exclusively exhibit AT2 receptors were studied also. Ang II-receptor expression was confirmed by Western blots of membrane lysates. NF-kappaB DNA binding in vitro was detected by electrophoretic shift assays. In addition, in vivo transactivation of a reporter gene construct with kappa enhancer coupled to luciferase also was investigated. Expression of the inhibitor of kappaB alpha (IkappaB-alpha) was detected by Western blots.RESULTS: In AT1 or AT2 receptor transfected cells, but not untransfected COS7 cells, 10-7 mol/L Ang II induced NF-kappaB DNA binding in vitro, as detected by electrophoretic shift assays and in vivo transactivation of a reporter gene construct. The AT2 receptor antagonist PD 123319 but not losartan attenuated Ang II-mediated NF-kappaB activation in COS7 cells transfected with AT2 receptors. While Ang II also induced NF-kappaB activation in PC12 cells, this activation was blocked by PD 123319. Finally, stimulation of GERs with Ang II led to the activation of NF-kappaB through both subtypes of Ang II receptors. Nuclear extracts from COS7 cells transfected with AT2 receptors and PC12 cells with NF-kappaB DNA-binding activity consisted of p50/p65 complexes. There was no difference in subunit composition of nuclear proteins from Ang II-stimulated AT1 receptor transfected COS7 cells. An artificial peptide (p-Amino-Phe6-Ang II) with a high affinity for the AT2 receptor also activated NF-kappaB. Ang II-induced activation of NF-kappaB was associated with degradation of IkappaB-alpha in all studied cell lines.CONCLUSIONS: Our results clearly demonstrate in various cell lines that Ang II induces NF-kappaB activation through AT2 receptors. These data may have important therapeutic consequences, because potential Ang II-mediated proinflammatory renal and cardiovascular effects may not be totally antagonized by the currently increased clinical use of AT1 receptor antagonists.     

血管紧张素Ⅱ及其受体表达在创面愈合过程中的变化及作用

目的 观察创面愈合过程中血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)及其受体表达的动态变化,以及这种变化与创面愈合过程中细胞增殖和凋亡活动之间的关系,探讨AngⅡ在创面愈合过程中的可能作用.方法 建立小鼠背部全层皮肤缺损创面模型,于创面形成后第0、1、3、5、7、9、11、13、15天切取创面组织标本,用ELISA法检测创面局部组织AngⅡ产生的变化;采用BrdU及TUNEL染色检测创面细胞增殖和凋亡的变化;用免疫组织化学染色和RT-PCR检测创面局部组织AngⅡ受体AT1和AT2表达的组织细胞定位和mRNA水平的变化.结果 小鼠全层皮肤缺损创面局部组织AngⅡ、BrdU标记指数均在伤后逐渐增加,并于第7天达到峰值后即逐渐下降.TUNEL染色阳性细胞数在伤后即开始缓慢增加,并于创面完成上皮化后增加趋势更为明显.正常小鼠皮肤AT1和AT2受体在整个表皮层均有阳性表达,但在真皮层,AT1和AT2受体仅在微血管内皮细胞有阳性表达.AT1受体在角质形成细胞、成纤维细胞均有表达,阳性染色信号在伤后逐渐增加,在第7天最强,以后逐渐下降.AT2受体阳性染色信号也在伤后逐渐增加,7 d以后则逐渐下降.但当创面上皮化完成后,AT2受体阳性染色信号再次增加.RT-PCR结果 显示:AT1和AT2受体mRNA均有表达,AT1、AT2受体mRNA表达在伤后第7天均达到峰值,此后则逐渐下降,且AT2受体mRNA表达在创面上皮化完成后表达再次增加.结论 在创面愈合过程中,AngⅡ可能通过其产生及受体表达的变化调控创面的愈合及后期的塑形改建.AT1受体可能与细胞增殖活动密切相关;AT2受体可能与细胞凋亡及愈合过程中组织重建有关.

Abstract：

Objective This study was undertaken to observe the change in the local level of angiotensin Ⅱ (Ang Ⅱ) and the expression of its corresponding receptors AT1 and AT2 during wound healing, and explore the possible role of Ang Ⅱ in wound healing . Methods A model of full-thickness cutaneous wound was developed on the back of C57/BL6 mice. Specimens were taken from the wound of each mouse on the day 0, 1, 3, 5, 7, 9, 11, 13 and 15 after wounding. The change in the generation of Ang Ⅱ in wounded tissue during the healing process was detected with ELISA. The proliferation and the apoptosis of cells were detected by bromodeoxyuridine (Brdu) and terminal deoxyuncleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) method in wounded skin during the healing process, respectively. The cellular localization and the mRNA level change of Ang Ⅱ receptors in wounded tissue during healing were detected with immunostaining and RT-PCR. Results Ang Ⅱ produced in wounded skin was increased in the first 7 days to reach the peak, and then gradually decreased during wound healing. BrdU labeling index was increased gradually in the first 7 days to reach the peak, and then gradually decreased during wound healing. The number of TUNEL-positive cells was increased slowly in the first 7 days after wounding. The increase in the number of TUNEL-positive cells was more markedly after epithelization of the wound. In normal mice, AT1 and AT2 receptor were found positively expressed in the whole epidermal layer, while positive expression was only found in the endothelial cells of the capillary vessels within the dermal layer, and positive expression was also found in appendages of the skin, i.e. hair follicle, sweat gland and sebaceous gland respectively. Positive staining signal of both AT1 and AT2 receptors were increased in the first 7 days to reach the peak, then gradually decreased. Expression of AT2R was increased again following the epithelization of wound. The result of RT-PCR showed that the expression of both AT1 and AT2 receptors was detectable, and AT1 receptor was increased in the first 7 days to the peak, and then gradually decreased during wound healing, while AT2 receptor expression reached its peak value on day 7, then gradually decreased, and increased again following the epithelization of wound. Conclusions These results indicate that Ang Ⅱ participate in wound repair and related to remolding in the late stage of wound healing through the change in production of angiotensin Ⅱ and expression of AT1 and AT2 receptors. AT1 receptor might be closely associated with cell proliferation,while AT2 receptor might play a role in cell apoptosis and remolding during wound healing.     

Angiotensin II type 1 and type 2 receptors reciprocally modulate pro-inflammatory/ pro-fibrotic reactions in activated splenic lymphocytes

Angiotensin II (Ang II) type 1 receptor (AT1R) has been confirmed to confer renoprotection in the progressive, immune-mediated nephritis in animal models as well as in humans. However, the relative contributions of direct AT1R blockade, indirect counteractivation of Ang II type 2 receptor (AT2R), or both, to renoprotection through AT1R antagonism remains to be clarified. Immunohistochemical studies in the nephritic kidney revealed that tubular epithelial cells and infiltrating immune cells were positive for AT1R and AT2R. In the present study, we investigated the action of Ang II on both receptors on immune cells. A subpopulation of lipopolysaccharide-activated splenic lymphocytes (mixed lymphocyte populations) was positive for AT1R and AT2R. Ang II alone could not induce gene expression of a pro-inflammatory chemokine JE or a pro-fibrotic cytokine transforming growth factor-beta1 in those cells. However, Ang II could significantly suppress the expression of both genes in those cells under AT1R blockade, and this action was mediated through AT2R. Conversely, the pro-inflammatory/pro-fibrotic gene expression could be enhanced by AT2R blockade, and this was mediated through AT1R. AT1R and AT2R expressed in activated immune cells can modulate pro-inflammatory and pro-fibrotic reactions reciprocally. In advanced immune-mediated nephritic kidneys, AT1R antagonism likely confers renoprotection via activation of AT2R.     

Angiotensin IV stimulates plasminogen activator inhibitor-1 expression in proximal tubular epithelial cells.

BACKGROUND: Angiotensin II (Ang II) has been shown to be implicated in the development of renal fibrosis in several forms of chronic glomerulonephritides, but the precise mechanisms of its effects remain unclear. It has recently been reported that Ang II stimulates the expression of plasminogen activator inhibitor-1 (PAI-1) in several cell lines. PAI-1 is a major physiological inhibitor of the plasminogen activator/plasmin system, a key regulator of fibrinolysis and extracellular matrix (ECM) turnover. PAI-1 induction by Ang II in endothelial cells seems to be mediated by Ang IV via a receptor that is different from Ang II type 1 and 2 receptors (AT1 and AT2). METHODS: In this study, we sought to evaluate the effects of Ang IV on PAI-1 gene and protein expression in a well-characterized and immortalized human proximal tubular cell line (HK2) by Northern blot and enzyme-linked immunosorbent assay. RESULTS: Ang IV stimulated PAI-1 mRNA expression, whereas it did not induce a significant increase in tritiated thymidine uptake after 24 hours of incubation. This effect was dose and time dependent. Ang IV (10 nM) induced a 7.8 +/- 3.3-fold increase in PAI-1 mRNA expression. The PAI-1 antigen level was significantly higher in conditioned media and the ECM of cells treated with Ang II and Ang IV than in control cells (both P < 0.02). Although Ang II induced a 4.2 +/- 2. 1-fold increase in PAI-1 mRNA expression, its effect underwent a dose-dependent reduction when amastatin, a potent inhibitor of the endopeptidases that catalyzes the conversion of Ang II to Ang IV, was added. In contrast, amastatin was not able to prevent the expression of PAI-1 mRNA induced by Ang IV. Finally, pretreatment of HK2 cells with losartan and N-Nicotinoyl-Tyr-N3-(Nalpha-CBZ-Arg)-Lys-His-Pro-Ile, the specific antagonists of AT1 and AT2 receptors, failed to modify PAI-1 mRNA expression as induced by Ang II. CONCLUSIONS: Our results demonstrate that Ang II stimulates PAI-1 mRNA expression and the production of its protein in human proximal tubular cells. This is mainly-if not exclusively-due to Ang IV, which acts on a receptor that is different than AT1 or AT2. Therefore, it can be hypothesized that the induction of PAI-1 by Ang IV may be implicated in the pathogenesis of renal interstitial fibrosis in several forms of chronic glomerulonephritides.     

Role of adipose tissue renin-angiotensin system in metabolic and inflammatory diseases associated with obesity

Obesity is a leading cause of death worldwide because of its associated inflammatory disorders such as hypertension, cardiovascular and kidney diseases, dyslipidemia, glucose intolerance, and certain types of cancer. Adipose tissue expresses all components of the renin-angiotensin system necessary to generate angiotensin (Ang) peptides for local function. The angiotensin type 1 (AT1) and type 2 (AT2) receptors mediate the effect of Ang II and recent studies have shown that both receptors may modulate fat mass expansion through upregulation of adipose tissue lipogenesis (AT2) and downregulation of lipolysis (AT1). Thus, both receptors may have synergistic and additive effects to promote the storage of lipid in adipose tissue in response to the nutrient environment. The production of angiotensinogen (AGT) by adipose tissue in rodents also contributes to one third of the circulating AGT levels. Increased adipose tissue AGT production in the obese state may be responsible in part for the metabolic and inflammatory disorders associated with obesity. This supports the notion that besides the traditional role of Ang II produced by the liver in the control of blood pressure, Ang II produced by the adipose tissue may more accurately reflect the role of this hormone in the regulation of fat mass and associated disorders.     

Renal expression of constitutive NOS and DDAH: separate effects of salt intake and angiotensin

BACKGROUND: Nitric oxide (NO) is generated from NO synthase (NOS) isoforms. These enzymes can be inhibited by asymmetric dimethylarginine, which is inactivated by N(G)-N(G)-dimethylarginine dimethylaminohydrolase (DDAH). The neuroneal (nNOS) type I and endothelial (eNOS) type III constitutive NOS isoforms are expressed predominantly in the macula densa and microvascular endothelium of the renal cortex, respectively. DDAH is expressed at sites of NOS expression. Since NO may coordinate the renal responses to angiotensin II (Ang II) and changes in salt intake, we tested the hypothesis that salt intake regulates the expression of nNOS, eNOS and DDAH by Ang II acting on type 1 (AT(1)) receptors. METHODS: Groups (N = 6) of rats were adapted to low-salt (LS) or high-salt (HS) intakes for 10 days. Other groups of LS and HS rats received the AT(1) receptor antagonist losartan for six days (to test the effects of salt independent of AT(1) receptors). A further group of HS rats received an infusion of Ang II for six days (to test the effect of Ang II independent of salt intake). RESULTS: Compared with HS rats, there was a significant (P < 0.05) increase in LS rats of nNOS protein in kidney and immunohistochemical expression in the macula densa, and of eNOS protein expression and immunohistochemical expression in the microvascular endothelium, and of DDAH protein expression. Losartan prevented these effects of salt on the expression of eNOS or DDAH, both of which were also increased by Ang II infusions in HS rats. In contrast, losartan did not prevent the effects of salt on nNOS expression, which was unresponsive to Ang II infusion. The generation of NO(2)(-) released by slices of renal cortex, in the presence of saturating concentrations of L-arginine, was increased by LS, compared to HS, independent of losartan and by Ang II during HS. CONCLUSION: The expressions of eNOS in cortical microvascular endothelium and DDAH in kidney are enhanced by Ang II acting on AT(1) receptors. The expression of nNOS in the macula densa is enhanced by salt restriction independent of Ang II or AT(1) receptors.