肾素-血管紧张素系统:新成员,新效应

肾素-血管紧张素系统（RAS）通过作用于心血管、肾脏、肾上腺，控制体液、电解质平衡以及动脉压，是机体重要的调控系统。经典的RAS主要成分有肾素、血管紧张素原（AGT）、血管紧张素Ⅰ（AngⅠ）、血管紧张素Ⅱ（AngⅡ）、血管紧张素转换酶（ACE）、血管紧张素受体1（AT1）、血管紧张素受体2（AT2R）。     

血管紧张素转换酶2在心血管系统中的意义

血管紧张素转换酶2（ACE2）是2000年才发现的肾素-血管紧张素系统的新成员,主要表达于心脏、肾脏和睾丸。ACE2的主要生物学效应是降解血管紧张素II（AngII）产生Ang1-7,Ang1-7具有舒张血管、抗增生、抗炎症的作用,对衰竭心脏有保护作用。研究发现ACE2基因敲除小鼠心功能受损,AngII水平升高。本文综述了ACE2的生物学效应以及在心血管系统中的意义。     

肾素-血管紧张素系统与胰腺炎

循环肾素一血管紧张素系统（RAS）是复杂的神经内分泌系统，也是应激反应系统，在维持机体血压和水、电解质平衡中发挥重要作用。血管紧张素原由肝脏产生，在肾脏产生的肾素作用下转换为血管紧张素Ⅰ（AngⅠ），由肺脏产生的血管紧张素转换酶（ACE）转换为血管紧张素Ⅱ（AngⅡ），在其他一些酶的作用下还可以产生其他一些活性物质，如AngⅡ、AngⅣ（Ang3～8）和Ang1～7，AngⅡ是主要的活性物质。血管紧张素受体包括AT1、AT2、AT3、AT4四种，AT1又分两个亚型，AT1a和AT1b。已知大部分AngⅡ活性是由AT1受体介导的。最近研究证明，很多组织器官存在局部RAS，如大脑、心脏、肾脏、性腺、肾上腺、胰腺等，这种组织RAS独立地通过旁分泌和（或）自分泌方式在各自组织器官的生理和病理生理过程中发挥重要作用，应用局部组织RAS拮抗剂可对这些组织器官疾病产生积极作用。[第一段]     

血管紧张素1-7：肾素-血管紧张素系统新调节因子

血管紧张素（Ang）1-7是肾素-血管紧张素系统的新调节因子，它能够拮抗AngⅡ的扩血管和促增殖等效应，并对肾脏发挥复杂的调节作用。通过药物作用干预血管紧张素酶2-Ang-（1-7）-Mas轴的功能，将会为心血管疾病、肾脏、肝脏疾病和糖尿病的治疗提供新的可能。     

血管紧张素转换酶2与高血压

血管紧张素转换酶2与血管紧张素转换酶一样参与肾素-血管紧张素系统中血管紧张素的代谢。它通过将血管紧张素Ⅱ水解成血管紧张素1-7对抗血管紧张素转换酶-血管紧张素Ⅱ代谢轴,是平衡肾素-血管紧张素系统内部调节的另一血管紧张素代谢通路。这种系统的内部调节在调节心血管系统活动中起重要作用,其平衡的破坏与高血压等相关疾病的发生发展密切相关,通过调节血管紧张素2来治疗高血压及其并发症可能是本世纪高血压治疗学上的新靶点。     

血管紧张素转换酶2基因多态性与肾脏损害

肾素血管紧张素系统（RAS）是体内调节神经体液和心血管功能的主要系统。新发现的多肽酶血管紧张素转换酶2（ACE2）通过产生血管紧张素（Ang）1-7和水解部分AngⅡ,拮抗由ACE水解产物AngⅡ介导的缩血管作用，并抑制血管平滑肌细胞增殖。研究表明糖尿病大鼠肾脏ACE2表达下降，糖尿病、高血压和代谢综合征均可损害肾脏，本研究旨在探讨这三种疾病患者ACE2基因A/C多态分布情况及其与肾脏损害的关系。     

血管紧张素转换酶2及其转换产物对心血管系统的作用

新近发现一种血管紧张素转换酶(ACE)同类酶,命名为血管紧张素转换酶2(ACE2),此酶在结构、功能等方面与ACE有所 不同,其转换产物血管紧张素-(1-9)和血管紧张素-(1-7)在功能上与血管紧张素转换酶转换产物AngⅡ部分相拮抗。本文就此酶 及其产物的研究做一综述。     

血管紧张素转换酶2的研究进展

血管紧张素转换酶2是肾素-血管紧张素系统的一个新成员,是迄今为止发现的第一个人类血管紧张素转换酶同族物。它能水解血管紧张素Ⅰ,生成血管紧张素(1-9),水解血管紧张素Ⅱ,生成血管紧张素(1-7),不仅能调节心血管功能和肾功能,而且在一系列炎症和免疫机制发挥作用的疾病发展过程中起一定作用。现就血管紧张素转换酶2的研究现状进行综述。     

血管紧张素转换酶Ⅱ与冠状动脉粥样硬化性心脏病的关系

肾素-血管紧张素系统与心血管疾病的发生发展有着复杂而密切的联系。近年来,一种新的血管紧张素转换酶Ⅱ被发现,血管紧张素转换酶Ⅱ的新的代谢通路对肾素-血管紧张素系统传统代谢通路可能有着负性调节作用,它参与了包括血管:紧张素在内的多种肽的代谢过程,在心血管疾病的病理生理方面发挥着重要作用。最近一些研究表明血管紧张素转换酶Ⅱ在动脉粥样硬化发展过程中起到了保护作用,这为动脉粥样硬化和心血管疾病的治疗和预防提供了新的策略。     

血管紧张素转化酶抑制剂和血管紧张素受体拮抗剂与肾保护作用

目前认为肾素血管紧张素系统（RAS）参与了慢性肾脏疾病的进展,阻断RAS能延缓肾脏疾病进展。血管紧张素转化酶抑制剂（ACEI）及血管紧张素ⅡAT1受体拮抗剂（AT1RA）是阻断RAS的主要药物。本文就此两类药物的肾保护作用进行综述,以供临床用药参考。     

Upregulation of hepatic angiotensin-converting enzyme 2 (ACE2) and angiotensin-(1-7) levels in experimental biliary fibrosis

BACKGROUND/AIMS: Angiotensin-converting enzyme 2 (ACE2), its product, angiotensin-(1-7) and its receptor, Mas, may moderate the adverse effects of angiotensin II in liver disease. We examined the expression of these novel components of the renin angiotensin system (RAS) and the production and vasoactive effects of angiotensin-(1-7) in the bile duct ligated (BDL) rat. METHODS: BDL or sham-operated rats were sacrificed at 1, 2, 3 and 4 weeks. Tissue and blood were collected for gene expression, enzyme activity and peptide measurements. In situ perfused livers were used to assess angiotensin peptide production and their effects on portal resistance. RESULTS: Hepatic ACE2 gene and activity (P<0.0005), plasma angiotensin-(1-7) (P<0.0005) and Mas receptor expression (P<0.01) were increased following BDL compared to shams. Perfusion experiments confirmed that BDL livers produced increased angiotensin-(1-7) (P<0.05) from angiotensin II and this was augmented (P<0.01) by ACE inhibition. Whilst angiotensin II increased vasoconstriction in cirrhotic livers, angiotensin-(1-7) had no effect on portal resistance. CONCLUSIONS: RAS activation in chronic liver injury is associated with upregulation of ACE2, Mas and hepatic conversion of angiotensin II to angiotensin-(1-7) leading to increased circulating angiotensin-(1-7). These results support the presence of an ACE2-angiotensin-(1-7)-Mas axis in liver injury which may counteract the effects of angiotensin II.     

Evidence against a major role for angiotensin converting enzyme-related carboxypeptidase (ACE2) in angiotensin peptide metabolism in the human coronary circulation

OBJECTIVE: To investigate the role of angiotensin-converting enzyme-related carboxypeptidase (ACE2) in angiotensin peptide metabolism in the human coronary circulation. METHODS: Angiotensin I and angiotensin II, and their respective carboxypeptidase metabolites, angiotensin-(1-9) and angiotensin-(1-7), were measured in arterial and coronary sinus blood of heart failure subjects receiving angiotensin-converting enzyme (ACE) inhibitor therapy and in normal subjects not receiving ACE inhibitor therapy. In addition, angiotensin I, angiotensin II and angiotensin-(1-7) were measured in arterial and coronary sinus blood of subjects with coronary artery disease before, and at 2, 5 and 10 min after, intravenous administration of ACE inhibitor. RESULTS: In comparison with normal subjects, heart failure subjects receiving ACE inhibitor therapy had a greater than 40-fold increase in angiotensin I levels, but angiotensin-(1-9) levels were low (1-2 fmol/ml), and similar to those of normal subjects. Moreover, angiotensin-(1-7) levels increased in parallel with angiotensin I levels and the angiotensin-(1-7)/angiotensin II ratio increased by 7.5-fold in coronary sinus blood. Intravenous administration of ACE inhibitor to subjects with coronary artery disease rapidly decreased angiotensin II levels by 54-58% and increased angiotensin I levels by 2.4- to 2.8-fold, but did not alter angiotensin-(1-7) levels or net angiotensin-(1-7) production across the myocardial vascular bed. CONCLUSIONS: The failure of angiotensin-(1-9) levels to increase in response to increased angiotensin I levels indicated little role for ACE2 in angiotensin I metabolism. Additionally, the levels of angiotensin-(1-7) were more linked to those of angiotensin I than angiotensin II, consistent with its formation by endopeptidase-mediated metabolism of angiotensin I, rather than by ACE2-mediated metabolism of angiotensin II.     

依那普利、厄贝沙坦及血管紧张素-（1—7）对快速心房起搏犬肾素-血管紧张素系统的影响

目的观察快速心房起搏模型犬血管紧张素转换酶2（ACE2）和血管紧张素III型受体（ATlR）mRNA表达的变化,以及应用依那普利、厄贝沙坦及血管紧张素（Ang）-（1-7）对其影响。方法健康成年杂种犬30只,分为5组：假手术组（S组）,心房起搏对照组（C组）,心房起搏＋依那普利组（EN组）,心房起搏＋厄贝沙坦组（IB组）,心房起搏＋血管紧张素-（1-7）组（A组）,每组6只。S组植入起搏器,但不行起搏刺激及药物干预。C组植入起搏器并起搏,但无药物干预。EN组及IB组分别于起搏开始前3d开始给予口服依那普利2mg·kg^-1·d^-1或厄贝沙坦60mg·kg^-1·d^-1。A组给予Ang-（1-7）6μg·kg^-1·h^-1持续静脉泵人。各组犬经500次／min快速心房起搏2周后,采集右心房肌标本,逆转录聚合酶链式反应（RT—PCR）检测心房肌组织中ACE2和ATlRmRNA表达。结果心房起搏组较假手术组ACE2表达降低,ATlR表达明显升高,应用依那普利、厄贝沙坦和Ang－（1-7）可使ACE2表达增加和ATIR水平下调。结论快速心房起搏2周可诱发心脏局部肾素－血管紧张素（RAS）系统的活化,依那普利、厄贝沙坦和Ang－（1-7）可抑制起搏后的RAS系统激活,降低心房颤动的易感性。Ang－（1-7）的心脏保护作用可能通过下调ATIR和上调ACE2来介导。     

血管紧张素转换酶2与糖尿病

肾素-血管紧张素系统（RAS）的过度激活在糖尿病及其慢性并发症的发生发展中发挥重要作用。血管紧张素转换酶（ACE）2作为RAS的新成员,可高效水解血管紧张素（Ang）Ⅱ生成Ang（1-7）,并竞争性作用于ACE的底物AngⅠ,与ACE共同调节RAS稳态。ACE2可改善胰岛血供、胰岛素分泌、减少胰岛纤维化及胰岛素抵抗,并延缓糖尿病慢性并发症的发生发展。深入研究ACE2,对防治糖尿病及其慢性并发症具有重要意义。     

Angiotensin-(1-7) is a modulator of the human renin-angiotensin system.

The renin-angiotensin system is important for cardiovascular homeostasis. Currently, therapies for different cardiovascular diseases are based on inhibition of angiotensin-converting enzyme (ACE) or angiotensin II receptor blockade. Inhibition of ACE blocks metabolism of angiotensin-(1-7) to angiotensin-(1-5) and can lead to elevation of angiotensin-(1-7) levels in plasma and tissue. In animal models, angiotensin-(1-7) itself causes or enhances vasodilation and inhibits vascular contractions to angiotensin II. The function of angiotensin-(1-5) is unknown. We investigated whether angiotensin-(1-7) and angiotensin-(1-5) inhibit ACE or antagonize angiotensin-induced vasoconstrictions in humans. ACE activity in plasma and atrial tissue was inhibited by angiotensin-(1-7) up to 100%, with an IC(50) of 3.0 and 4.0 micromol/L, respectively. In human internal mammary arteries, contractions induced by angiotensin I and II and the non-ACE-specific substrate [Pro(11),D-Ala(12)]-angiotensin I were antagonized by angiotensin-(1-7) (10(-5) mol/L) in a noncompetitive way, with a 60% inhibition of the maximal response to angiotensin II. Contractions to ACE-specific substrate [Pro(10)]-angiotensin I were also inhibited, an effect only partly accounted for by antagonism of angiotensin II. Angiotensin-(1-5) inhibited plasma ACE activity with a potency equal to that of angiotensin I but had no effect on arterial contractions. In conclusion, angiotensin-(1-7) blocks angiotensin II-induced vasoconstriction and inhibits ACE in human cardiovascular tissues. Angiotensin-(1-5) only inhibits ACE. These results show that angiotensin-(1-7) may be an important modulator of the human renin-angiotensin system.     

Possible involvement of angiotensin-converting enzyme 2 and Mas activation in inhibitory effects of angiotensin II Type 1 receptor blockade on vascular remodeling

We explored the roles of angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7), and Mas activation in angiotensin II type 1 receptor blockade-mediated attenuation of vascular remodeling. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. After cuff placement, the mRNA level of both ACE2 and Mas was markedly decreased in wild-type mice, whereas ACE mRNA was not changed. Immunostaining of ACE2 and Mas was observed mainly in the media and was reduced in the injured artery. Administration of angiotensin-(1-7) decreased neointimal formation after cuff placement, whereas administration of [D-Ala(7)] angiotensin-(1-7), a Mas antagonist, increased it. Consistent with these results, we also demonstrated that neointimal formation induced by cuff placement was further increased in ACE2 knockout mice. In angiotensin II type 1a receptor knockout mice, mRNA expression and immunostaining of ACE2 and Mas in the injured artery were greater, with less neointimal formation than in wild-type mice. Increased ACE2 expression in the injured artery was also observed by treatment of wild-type mice with an angiotensin II type 1 receptor blocker, olmesartan. These results suggested that activation of the ACE2-angiotensin-(1-7)-Mas axis is at least partly involved in the beneficial effects of angiotensin II type 1 receptor blockade on vascular remodeling.     

Sodium status and angiotensin-converting enzyme inhibition: effects on plasma angiotensin-(1-7) in healthy man

OBJECTIVE: Angiotensin-converting enzyme (ACE) inhibitors provide effective intervention for cardiovascular and renal disease. Changes in angiotensin-(1-7) have been proposed to be involved in the mechanism of action of ACE inhibition (ACEi). In particular, an altered balance between angiotensin II and angiotensin-(1-7) might be involved. A shift in sodium status modifies the activity of the renin-angiotensin-aldosterone system and the effects of ACEi, but its effects on angiotensin-(1-7) are unknown. We therefore studied the effect of a shift in sodium intake on angiotensin-(1-7), during placebo and ACEi. METHODS: A double-blind, placebo-controlled study was conducted in 17 healthy men. The subjects were studied for two 2-week periods: 20 mg/day enalapril and placebo. The first week of each period they used a 50 mmol Na+ diet [low sodium (LS)], the second week a 200 mmol Na+ diet. Angiotensin levels and blood pressure were measured at the end of each week. RESULTS: During placebo, LS intake elicited a three-fold rise in ang-(1-7) that paralleled the rise in other components of the renin-angiotensin system. During ACEi LS did not affect angiotensin II, but did induce a clear-cut rise in angiotensin-(1-7)--to the extent that angiotensin-(1-7) was highest during combination of ACEi and LS. Consequently, during ACEi LS shifted the balance between angiotensin-(1-7) and angiotensin II towards angiotensin-(1-7). CONCLUSION: The sodium status modifies levels of angiotensin-(1-7). During ACEi angiotensin-(1-7) is still subject to stimulation by sodium restriction, and provides opportunity for therapeutic manipulation. Exploration of this opportunity in patient populations may lead to strategies to improve therapeutic benefits of ACEi.     

ACE基因I／D、AT1R基因A1166C多态性与奥美沙坦酯降压作用的关系

目的探讨血管紧张素转换酶（ACE）基因I／D、血管紧张素Ⅱ-1型受体（ATlR）基因A1166C多态性与奥美沙坦酯降压作用的关系。方法76例轻、中度高血压（EH）患者服用奥美沙坦酯治疗8周;用聚合酶链式反应一限制性片段长度多态性对其血白细胞基因组DNA肾索-血管紧张素-醛固酮系统基因多态性位点ACEI／D、ATlRA1166C基因型进行检测。结果ACE基因含D等位基因患者的SBP、DBP、脉压降幅及降压总有效率均高于含I等位基因者,DD＋AA基因型患者的SBP降幅高于DD＋AC基因型者（P均〈0．05）。结论ACE基因含D等位基因EH患者对奥美沙坦酯降压治疗敏感;ACE、AT1R基因联合作用可能影响奥美沙坦酯的降压疗效。