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Antiatherosclerotic effects of the novel angiotensin receptor antagonist Fimasartan on plaque progression and stability in a rabbit model: a double-blind placebo-controlled trial. J Cardiovasc Pharmacol 2014; 62:229-36. [PMID: 23615162 DOI: 10.1097/fjc.0b013e318297458b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To evaluate the effect of the novel angiotensin receptor blocker Fimasartan on the development of atherosclerosis and plaque stabilization in an animal model. METHODS Twenty-four rabbits received an aortic balloon injury from 30 cm to a level just above the aortic valve to the iliac bifurcation using 3 Fr Fogarty catheters on third day of the experiment, followed by a 1% cholesterol diet for 8 weeks. The rabbits were randomized to receive placebo or 3 or 6 mg · kg⁻¹ · d⁻¹ Fimasartan. The study was double blinded. The rabbits started receiving their medications 2 days before the aortic balloon injury and treatment continued. Atherosclerosis burden was determined by calculating the intima-media ratio of the infrarenal portion of the aorta because the bulk of the atherosclerotic burden was limited to the infrarenal region. The frequency of plaque disruption with thrombosis and the proportions of the plaques that were occupied by macrophages, smooth muscle cells, and collagen were determined. RESULTS Relative to the placebo group, the Fimasartan-treated rabbits had less atherosclerosis [intima-media ratio (mean ± SEM) of 1.14 ± 0.21 vs. 1.51 ± 0.26, P = 0.005], fewer disrupted plaques with thrombi (3 of 16 vs. 5 of 8, P = 0.047), lower proportion of macrophages (17.5% ± 2.5% vs. 26% ± 3.5%, P = 0.03), higher proportion of smooth muscle cells (43.5% ± 8.3% vs. 11.9% ± 2.1%, P = 0.001), and higher proportion of collagen (34.3% ± 6.4% vs. 19.7% ± 2.1%, P = 0.02). CONCLUSIONS These results show that the newly developed angiotensin receptor blocker, Fimasartan, attenuated atherosclerosis progression and reduced macrophage accumulation in the rabbit aortic plaques.
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Measuring and targeting aldosterone and renin in atherosclerosis-a review of clinical data. Am Heart J 2011; 162:585-96. [PMID: 21982648 DOI: 10.1016/j.ahj.2011.06.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Accepted: 06/21/2011] [Indexed: 01/13/2023]
Abstract
Our understanding of the development and progression of atherosclerosis has increased substantially over the past decades. A significant role for the renin-angiotensin-aldosterone system (RAAS) in this process has gained appreciation in recent years. Preclinical and clinical studies have associated components of the RAAS with various cardiovascular disease conditions. Classically known for its contribution to hypertension, dysregulation of the system is now also believed to promote vascular inflammation, fibrosis, remodeling, and endothelial dysfunction, all intimately related to atherosclerosis. The reduction in cardiovascular mortality and morbidity, as seen with the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, supports the concept that RAAS is involved in the pathogenesis of atherosclerotic disease. However, the underlying molecular mechanisms of the pathophysiology remain to be completely understood. Evidence points toward additional benefit from therapeutic approaches aiming at more complete inhibition of the system and the possible utility of renin or aldosterone in the prediction of cardiovascular outcome. This review will summarize the current knowledge from clinical studies regarding the presumptive role of renin and aldosterone in the prediction and management of patients with atherosclerosis. For this purpose, a literature search was performed, focusing on available clinical data regarding renin or aldosterone and cardiovascular outcome.
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Chon H, Neumann J, Boer P, Joles JA, Braam B. Enhanced Angiotensin II type 1 receptor expression in leukocytes of patients with chronic kidney disease. Eur J Pharmacol 2011; 666:205-10. [PMID: 21640098 DOI: 10.1016/j.ejphar.2011.05.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 04/20/2011] [Accepted: 05/11/2011] [Indexed: 11/26/2022]
Abstract
Previously, we demonstrated increased Angiotensin II type I receptor expression in leukocytes from patients with untreated, but not in treated, essential hypertension (essential hypertension). We hypothesized that the Angiotensin II AT1 receptor is also increased in leukocytes from patients with chronic kidney disease, however and can still be corrected with combined anti-hypertensive treatment with renin-angiotensin system (RAS) blockers and statins. Blood pressure, cholesterol, renal function oxidative stress parameters, inflammation, and leukocyte Angiotensin II AT1 receptor mRNA expression were measured both on and (6 weeks) off treatment. Data were compared to data of 10 healthy control subjects. Untreated chronic kidney disease patients (n=20) had higher blood pressure, cholesterol and leukocyte Angiotensin II AT1 receptor mRNA expression, but no different ox-LDL, thiobarbituric acid reactive substances, paraoxonase activity or hs-CRP. OxLDL and Lipoprotein(a) were increased in untreated chronic kidney disease. Angiotensin II AT1 receptor expression inversely correlated with renal function (R(2)=0.15, P<0.03) and Lipoprotein(a) but not with the other parameters. Treatment with RAS blockers and statins normalized blood pressure and cholesterol, however it did not correct enhanced leukocyte Angiotensin II AT1 receptor expression. Leukocyte Angiotensin II AT1 receptor expression is inappropriately high in chronic kidney disease, correlates inversely with renal function and does not depend on antihypertensive and lipid-lowering treatment. The uremic environment seems to dominate over previously reported actions of high blood pressure and cholesterol to enhance leukocyte Angiotensin II AT1 receptor expression.
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Affiliation(s)
- Helena Chon
- Nephrology and Hypertension, UMC Utrecht, Utrecht, Netherlands
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Sun P, Zhang W, Zhu W, Yan H, Zhu J. Expression of renin-angiotensin system on dendritic cells of patients with coronary artery disease. Inflammation 2010; 32:347-56. [PMID: 19669395 DOI: 10.1007/s10753-009-9141-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Dendritic cells (DCs) and renin-angiotensin system (RAS) have both been reported to contribute to the pathogenesis of atherosclerosis. Recently researches find the RAS expression on DCs and its effect on DCs' differentiation and proinflammatory function. The pattern of RAS expression on DCs derived from normal monocytes vs that on DCs derived from cornoary artery diease was investigated. In 82 coronary artery disease (CAD) patients and healthy controls (CTL), expressions of angiotensin I-converting enzyme (ACE), angiotensin AT1 receptor and DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN) on DCs were measured by western-blot: CAD patients had an increased expression of ACE, AT1 receptor and DC-SIGN compared to controls especially in acute myocardial infarction (AMI). Cardiovascular risk factors of cardiovascular disease and circulating anigotensin II (Ang II) were assessed and found increased in AMI compared with CTL. The DC-SIGN and high-sensitivity C-reactive protein (hsCRP) also had significant correlations with RAS expression on DCs. Our research demonstrated the RAS expressions on DCs and their increase in CAD especially AMI. The RAS activation on DCs may cause a series of changes such as enhancing recruitment of DCs, activating the T cells and increasing their proinflammtory functions. The recruitment and T cells contact ability of DCs increases through DC-SIGN may be one of pathogenesis of atherosclerosis and this function may promoted by tissue RAS. CRP may also have some effect to the local RAS exprssion on DCs.
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Affiliation(s)
- Peiyu Sun
- Department of Cardiology, School of Medicine, the First Affiliated Hospital of Zhejiang University, No 79, Qin chun Road, Hangzhou 310003, Zhejiang Province, China
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Aihara K, Ishii H, Yoshida M. Casein-derived tripeptide, Val-Pro-Pro (VPP), modulates monocyte adhesion to vascular endothelium. J Atheroscler Thromb 2010; 16:594-603. [PMID: 19907102 DOI: 10.5551/jat.729] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM A food-derived bioactive tripeptide, Val-Pro-Pro (VPP), has been shown to possess angiotensin I-converting enzyme (ACE) inhibitory activity and foods containing such peptides exhibit an anti-hypertensive effect in clinical settings. METHODS The present study focused on the effect of VPP on monocyte adhesion to endothelium under flow conditions using phorbol 12-myristate 13-acetate (PMA)-stimulated monocytic THP-1 cells. RESULTS Pre-incubation of THP-1 cells with VPP (1 mM, 24 hours) significantly decreased the PMA-induced adhesion of THP-1 cells (p<0.05) to human umbilical vein endothelial cells (HUVECs). PMA-induced up-regulation of beta1 and beta2 integrin activation in THP-1 cells was downregulated by VPP, which significantly suppressed only the PMA-induced phosphorylation of JNK (p<0.05) in THP-1 cells. In addition, preincubation of THP-1 with SP600125, a specific inhibitor of JNK, resulted in significant reduction of the PMA-induced adhesion of THP-1. Interestingly, another tripeptide with comparable ACE inhibitory activity, Leu-Gly-Pro (LGP), failed to reduce the PMA-induced adhesion of THP-1, suggesting a distinct anti-inflammatory effect of VPP on THP-1 adhesion. CONCLUSION These observations suggest that VPP moderates monocyte adhesion to inflamed endothelia via attenuation of the JNK pathway in monocytes, which might contribute to the primary prevention of atherosclerosis.
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Affiliation(s)
- Kotaro Aihara
- Functional Food and Drink Development Laboratory, Calpis Co., Ltd, Japan
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Kimouli M, Miyakis S, Georgakopoulos P, Neofytou E, Achimastos AD, Spandidos DA. Polymorphisms of fractalkine receptor CX3CR1 gene in patients with symptomatic and asymptomatic carotid artery stenosis. J Atheroscler Thromb 2009; 16:604-10. [PMID: 19755791 DOI: 10.5551/jat.1107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM The chemokine fractalikine is expressed in vascular endothelium, exerting a pro-atherogenic effect. Two single-nucleotide polymorphisms of the CX3CR1 gene (T280M and V249I) affect frac-talkine receptor expression and function. We aimed to assess the prevalence of CX3CR1 polymor-phisms and the association with ischemic cerebrovascular attacks in a cohort of carotid atheromatous disease patients and age-matched controls. METHODS Using PCR-RFLP, we analyzed allelotypes for T280M and V249I in 150 patients with and 151 controls without carotid atherosclerosis assessed using carotid duplex ultrasound; the subjects were patients admitted for any reason to a tertiary hospital. Genotype data were compared with modifiable risk factors for cerebrovascular disease and the reason for admission, using ischemic stroke as an endpoint. Stroke types associated with carotid atherosclerosis were analysed separately. RESULTS The M280 allelic frequency was lower among carotid atherosclerosis patients than controls (0.15 versus 0.23, adjusted OR 0.47, 95% CI 0.30-0.74). Absence of M280 allele was an indepen-dent factor associated with carotid atherosclerosis (OR 3.70, 95% CI 1.92-7.14), stronger than hypertension, dyslipidemia, diabetes and cigarette smoking. The I249 allele was also under-repre-sented in carotid atherosclerosis; this was not statistically significant. T280M and V249I genotypes were not associated with admission due to ischemic stroke of the large vessel subtype (TOAST classi-fication, 73 episodes), whereas carotid atherosclerosis, previous ischemic event, age, hypertension, diabetes, hyperlipidemia and cigarette smoking were all independently associated. CONCLUSIONS The M280 fractalkine receptor gene allele is associated with a lower risk of carotid ath-eromatous disease, independent from the modifiable cerebrovascular risk factors.
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Affiliation(s)
- Maria Kimouli
- Laboratory of Virology, Medical School, University of Crete, Greece
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Wu R, Zeng Y. Does angiotensin II-aldosterone have a role in radiation-induced heart disease? Med Hypotheses 2008; 72:263-6. [PMID: 19095366 DOI: 10.1016/j.mehy.2008.09.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 08/18/2008] [Accepted: 09/03/2008] [Indexed: 11/18/2022]
Abstract
Radiation-induced heart disease (RIHD) is the potentially lethal side effect of radiation therapy. Clinical trials and epidemiologic studies show the adverse impact of RIHD on the outcome of long-term cancer survivors. However, what factors affect RIHD and how RIHD develop are not yet clear. On the other hand, as we all known, angiotensin II (Ang II) and aldosterone play a vital pathophysiological role in the common cardiovascular disease, including hypertension, atherosclerosis, heart failure, myocardial infarction and cardiac hypertrophy. The pathophysiology of these various syndromes is similar, starting by prior microvascular injury that leads to subsequent myocardium ischemia, all of which cause late fibrous scars. So the pathophysiology of RIHD is similar to the common heart diseases induced by angiotensin-aldosterone. But the effect of angiotensin-aldosterone on RIHD has little been studied. Thus, in the present hypothesis we suggest that angiotensin II-aldosterone plays an important pathophysical role in RIHD, which was confirmed by our pilot study.
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Affiliation(s)
- Rong Wu
- Department of Medical Oncology, Shengjing Hospital of China Medical University, 39 Huaxiang Road, Shenyang 110022, PR China
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Crocetin suppresses angiotensin II-induced vascular smooth-muscle cell proliferation through inhibition of ERK1/2 activation and cell-cycle progression. J Cardiovasc Pharmacol 2008; 50:519-25. [PMID: 18030061 DOI: 10.1097/fjc.0b013e31813c114e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Excessive proliferation of vascular smooth cells (VSMCs) plays a critical role in the development of atherosclerosis, and inhibition of VSMCs proliferation has been proved to be beneficial to this disease. In the present study, we investigated the antiproliferative effect of crocetin, a carotinoid (Fig. 1, >98%, HPLC) with potent antioxidant capacity, on bovine aortic VSMCs (BASMCs), and the possible mechanisms involved. The results indicate that crocetin potently inhibited AngII-induced BASMC proliferation, as evaluated by MTT assay and [3H]-thymidine incorporation assay. Flow cytometry analysis showed that crocetin markedly blocked AngII-induced cell-cycle progression by arresting the cells in the G0/G1 phase. Consistently, crocetin markedly suppressed AngII-induced activation of extracellular signal-regulated kinase1/2 (ERK1/2) and its downstream effector c-fos expression, which is a prerequisite for cell-cycle progression. In addition, crocetin significantly decreased AngII-induced intracellular reactive oxygen species and increased the activity of superoxide dismutase. Taken together, these results indicate that crocetin was capable of inhibiting BASMC proliferation by blocking cell-cycle progression, which might be associated with the suppression of ERK1/2 activation and c-fos expression. These results might be related, at least partly, to the antioxidant property of crocetin.
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Kojima C, Kawakami A, Takei T, Nitta K, Yoshida M. Angiotensin-Converting Enzyme Inhibitor Attenuates Monocyte Adhesion to Vascular Endothelium through Modulation of Intracellular Zinc. J Pharmacol Exp Ther 2007; 323:855-60. [PMID: 17878405 DOI: 10.1124/jpet.107.127944] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To elucidate an anti-inflammatory role of angiotensin-converting enzyme inhibitors (ACEIs) in cardiovascular disease, we studied the effect of ACEIs in monocyte adhesion to endothelial cells and underlying molecular mechanisms. Treatment of human monocytic THP-1 cells with monocyte chemoattractant protein-1 (MCP-1; 100 ng/ml; 10 min) significantly increased their adhesion to human umbilical vein endothelial cells (HUVECs) under flow condition (P < 0.001). Preincubation of THP-1 cells with imidaprilat (50 nM; 4 h), an active metabolite of imidapril, reduced MCP-1-triggered THP-1 cell adhesion (P < 0.01). Similar effects were obtained with experiments using human peripheral monocytes (P < 0.05). MCP-1 activated protein kinase C (PKC)alpha in THP-1 cells, resulting in the up-regulation of alpha4 and beta2 integrin. Imidaprilat attenuated MCP-1-induced PKC activation and integrin up-regulation in THP-1 cells. Imidaprilat also inhibited THP-1 cell adhesion induced by phorbol 12-myristate 13-acetate (PMA), a potent PKC activator. In attempt to elucidate the mechanisms for the modulation of PKC activity by imidaprilat, we found that MCP-1 or PMA increased labile zinc in THP-1 cells, which was canceled by imidaprilat. Indeed, zinc/pyrithione activated PKC and increased THP-1 cell adhesion. Zinc chelator as well as PKC inhibitor inhibited these processes, suggesting the role for labile zinc in PKC activation and THP-1 cell adhesion. Imidaprilat attenuated zinc/pyrithione-induced PKC activation and THP-1 cell adhesion. These data suggest that ACEI reduces MCP-1 or PMA-triggered monocyte adhesion to activated HUVECs by modulating labile zinc in monocytes. Our findings may point out a novel anti-inflammatory mechanism of ACEIs in atherogenesis.
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Affiliation(s)
- Chiari Kojima
- Life Science and Bioethics Research Center, Tokyo Medical and Dental University, 1-5-45 Yushima Bldg. D-9, Bunkyo-ku, Tokyo 113-8519, Japan
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Abstract
There is convincing evidence that angiotensin II, through activation of the angiotensin II type 1 (AT1) receptor, is involved in the atherosclerotic process. Similarly, angiotensin receptor blockers decrease vascular inflammation, hypertrophy and thrombosis, which are the key components of the progression of atherosclerosis. In addition, in several animal models, angiotensin receptor blockade was able to inhibit atherosclerosis. However, the effects of angiotensin receptor blockers on clinical outcome in cardiovascular patients remains to be established. Contradictory results have been found on the reduction of the risk on myocardial infarctions and in-stent restenosis, although there is solid evidence for cerebroprotective effects of these receptor blockers. These differences may be related to the role of the AT2 receptor. This review discusses the role of angiotensin II and angiotensin receptor blockers in the atherosclerotic process and its translation into clinical practice.
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Affiliation(s)
- Adriaan A Voors
- University Medical Center Groningen, Thoraxcenter, Department of Cardiology, Groningen, The Netherlands.
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Johansson ME, Wickman A, Skøtt O, Gan LM, Bergström G. Blood pressure is the major driving force for plaque formation in aortic-constricted ApoE−/− mice. J Hypertens 2006; 24:2001-8. [PMID: 16957560 DOI: 10.1097/01.hjh.0000244949.65040.de] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Using an aortic constriction model in mice, we studied whether the increase in pressure or the activation of the renin-angiotensin system (RAS) and its main receptors is the main driving force for plaque progression. METHODS Male ApoE mice underwent sham surgery or placement of a suprarenal silver clip around the aorta (AoC). Half the group was treated with the selective AT1 receptor antagonist losartan (30 mg/kg per day) for 4 weeks. RESULTS Anesthetized mean arterial pressure (MAP) was increased in AoC mice compared to sham (106 +/- 3 versus 90 +/- 1 mmHg, P < 0.001). Losartan reduced MAP in sham mice (78 +/- 2 mmHg, P < 0.01) but not in AoC (AoC losartan 104 +/- 2 mmHg). Plasma renin concentration (PRC) was increased in AoC mice compared to sham [1.6 +/- 0.3 versus 0.8 +/- 0.2 milliGoldblatt units (mGU)/ml, P < 0.001]. Losartan treatment augmented this difference (18.7 +/- 3.7 versus 4.6 +/- 1.7 mGU/ml, P < 0.01). AT2 receptor mRNA expression was increased 5.8-fold by aortic constriction in thoracic aorta (P < 0.05) and the major site for expression of the AT2 receptor protein was within the plaques. The plaque area was increased in AoC mice compared to sham (0.61 +/- 0.09 versus 0.07 +/- 0.01%, P < 0.001); however, losartan did not alter plaque area. CONCLUSIONS Our data do not support a role for the AT1 receptor in the progression of atherosclerosis in this model, since blockade with losartan did not alter plaque distribution. Furthermore, we found no support for the counteraction of atherogenesis by increased activity of the RAS acting on the AT2 receptor. Our data suggest that increased pressure is the main driving force for atherosclerosis in this model.
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Affiliation(s)
- Maria E Johansson
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
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Struwe E, Krammer K, Dötsch J, Metzler M, Dörr HG, Cesnjevar R, Rascher W, Koch A. No evidence for angiotensin type 2 receptor gene polymorphism in intron 1 in patients with coarctation of the aorta and Ullrich-Turner syndrome. Pediatr Cardiol 2006; 27:636-9. [PMID: 16944335 DOI: 10.1007/s00246-005-1049-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Accepted: 08/24/2005] [Indexed: 01/09/2023]
Abstract
In male patients with congenital anomalies of the kidney and urinary tract, an increased incidence of a polymorphism in the angiotensin type 2 receptor gene (AT2R) has been identified. The AT2R has been shown to be involved in apoptosis, particularly during embryogenesis. The aim of this study was to examine the A-->1675G transition polymorphism in intron 1 of the AT2R gene that is located on the X chromosome in patients with coarctation of the aorta (CoA) with and without Ullrich-Turner syndrome (UTS). Screening of DNA samples was performed with restriction fragment length polymorphism analysis. Ninety-seven patients with CoA, 28 girls with UTS, 10 girls with UTS and CoA, and 96 control individuals were studied. There was no significant difference in the distribution of A and G-genotypes in any of the patient groups compared to controls. An A-->1675G transition in the AT2R gene seems not to be involved in the pathogenesis of aortic coarctation.
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Affiliation(s)
- E Struwe
- Children's Hospital, University of Erlangen-Nürnberg, Loschgestrasse 15, D-91045 Erlangen, Germany
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Miyazaki M, Takai S. Tissue angiotensin II generating system by angiotensin-converting enzyme and chymase. J Pharmacol Sci 2006; 100:391-7. [PMID: 16799256 DOI: 10.1254/jphs.cpj06008x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It had been believed that angiotensin II (Ang II) was produced by the renin-angiotensin system (RAS), which was established in the 1950's. After a while, people realized that the multiple functions of Ang II could not be explained by the conventional RAS. We have tried to determine the existence of the tissue Ang II generating system. At first, we found that vascular angiotensin-converting enzyme (ACE) was increased to generate local Ang II in the vessels of hypertension and was enhanced in lipid-loaded atherosclerosis, to respond to ACE inhibitor or Ang II antagonist (ARB). In both cases, Ang II production in vessels was independent from the systemic RAS that was estimated by the plasma renin activity. On the way to clarifying the roles of the vascular ACE, we noticed that vascular Ang II production was not completely suppressed by ACE inhibitor alone. This evidence led us to discover different types of chymase as a new Ang II producing enzyme. Now, we have obtained a strategy to distinguish the Ang II one by one, that is, circulating RAS derived, tissue ACE derived, and chymase derived. It is essential to understand not only the intracellular mechanisms of Ang II but also the process of Ang II productions in each disease to show accurate indications of the effectiveness of ACE inhibitor, ARB, and chymase inhibitor.
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Affiliation(s)
- Mizuo Miyazaki
- Department of Pharmacology, Osaka Medical College, Japan.
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Eagleton MJ, Ballard N, Lynch E, Srivastava SD, Upchurch GR, Stanley JC. Early increased MT1-MMP expression and late MMP-2 and MMP-9 activity during Angiotensin II induced aneurysm formation. J Surg Res 2006; 135:345-51. [PMID: 16716358 DOI: 10.1016/j.jss.2006.03.026] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 03/03/2006] [Accepted: 03/11/2006] [Indexed: 11/30/2022]
Abstract
BACKGROUND Angiotensin II (Ang II) is associated with a variety of cardiovascular diseases including aneurysm formation. The aim of this study was to evaluate the temporal changes in MT1-matrix metalloproteinase (MMP) and MMP-2 and -9 expression and activity during the course of Ang II induced experimental aneurysm formation. METHODS Apolipoprotein E knockout mice (ApoE null) were infused with either 1000 ng/kg/min of Ang II (n = 20) or saline (n = 20) and then sacrificed at 7, 14, 21, and 28 days of infusion (n = 5/group/strain). Aortic diameters were measured by digital microscopy. Systolic blood pressure (SBP) was measured in the rodent tail. Suprarenal abdominal aortas had MT1-MMP mRNA levels and MMP-2 and MMP-9 mRNA levels and activity quantitated using reverse transcriptase-polymerase chain reaction (rt-PCR) and gelatin zymography, respectively. Statistical analyses included nonpaired t-test, Fisher's exact test, and analysis of variance (ANOVA). RESULTS Aneurysms occurred in 40, 40, 20, and 80% of ApoE null-Ang II mice at 7, 14, 21, and 28 days, respectively. An early and significant rise in MT1-MMP mRNA occurred in ApoE null mice infused with Ang II mice, while there was no significant change in MMP-2 or MMP-9 mRNA levels. Total MMP-2 and MMP-9 activity increased over time in ApoE null mice infused with Ang II, peaking at 28 days (ANOVA, P < 0.01). SBP was significantly elevated by 7 days in ApoE null mice infused with Ang II compared to ApoE null mice infused with saline (123 +/- 16 versus 102 +/- 6 mm Hg, P < 0.05). CONCLUSIONS Angiotensin II induces an early increase in aortic MT1-MMP expression with a subsequent increase in MMP-2 and MMP-9 activity. The process by which these changes cause aneurysm formation warrants further investigation.
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Affiliation(s)
- Matthew J Eagleton
- Section of Vascular Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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Chon H, Verhaar MC, Koomans HA, Joles JA, Braam B. Role of Circulating Karyocytes in the Initiation and Progression of Atherosclerosis. Hypertension 2006; 47:803-10. [PMID: 16520401 DOI: 10.1161/01.hyp.0000210554.61293.90] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiovascular disease is still hard to predict in an individual. The main focus in cardiovascular research has been on endothelial cells and vascular smooth muscle cells of the vessel wall and their interactions with the blood flow. Alterations in the properties of the blood have received a lot of attention in biochemical terms. Interestingly, alterations in the properties of circulating cells have received less attention. We propose that presence of 1 or more risk factors together with normal physiological stimuli induce redox-dependent changes in leukocyte gene transcription with pathophysiological responses. Thus, risk factors render leukocytes hypersensitive to normal stimuli. Risk factors can be subdivided into physical and chemical factors. Superimposed on physiological regulators of leukocyte function, these risk factors promote a cellular pro-oxidative state. Redox-sensitive transcription factors are activated, leading to responses involving inflammation, adhesion, migration, and additional reactive oxygen species generation. As a consequence, monitoring of individual gene expression signatures of these cells could well increase our understanding of the mechanisms by which leukocytes and, in particular, monocytes function. Furthermore, transcriptomes of these cells could be used to investigate the aggressiveness of the atherosclerotic process or to guide treatment in the patient with risk factors for atherosclerosis.
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Affiliation(s)
- Helena Chon
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
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Saini HK, Xu YJ, Arneja AS, Tappia PS, Dhalla NS. Pharmacological basis of different targets for the treatment of atherosclerosis. J Cell Mol Med 2006; 9:818-39. [PMID: 16364193 PMCID: PMC6740287 DOI: 10.1111/j.1582-4934.2005.tb00382.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The development of atherosclerotic plaque is a highly regulated and complex process which occurs as a result of structural and functional alterations in endothelial cells, smooth muscle cells (SMCs), monocytes/macrophages, T-lymphocytes and platelets. The plaque formation in the coronary arteries or rupture of the plaque in the peripheral vasculature in latter stages of atherosclerosis triggers the onset of acute ischemic events involving myocardium. Although lipid lowering with statins has been established as an important therapy for the treatment of atherosclerosis, partially beneficial effects of statins beyond decreasing lipid levels has shifted the focus to develop newer drugs that can affect directly the process of atherosclerosis. Blockade of renin angiotensin system, augmentation of nitric oxide availability, reduction of Ca(2+) influx, prevention of oxidative stress as well as attenuation of inflammation, platelet activation and SMC proliferation have been recognized as targets for drug treatment to control the development, progression and management of atherosclerosis. A major challenge for future drug development is to formulate a combination therapy affecting different targets to improve the treatment of atherosclerosis.
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Affiliation(s)
- Harjot K Saini
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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17
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Johansson ME, Wickman A, Fitzgerald SM, Gan LM, Bergström G. Angiotensin II, type 2 receptor is not involved in the angiotensin II-mediated pro-atherogenic process in ApoE-/- mice. J Hypertens 2005; 23:1541-9. [PMID: 16003181 DOI: 10.1097/01.hjh.0000174078.95745.77] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Angiotensin II (Ang II) accelerates atherogenesis in ApoE mice via the angiotensin II, type 1 receptor (AT1) while the type 2 receptor (AT2) is suggested to counteract atherogenesis. To confirm and further explore this possibility, we studied the effect of AT2 receptor antagonism on Ang II-accelerated atherosclerosis. METHODS ApoE mice were fed a standard or high cholesterol diet (1.25%) for 4 weeks. Mice on each diet were treated with either Ang II (0.5 microg/kg per min) or Ang II in combination with PD123319 (3 mg/kg per day). Plaque distribution was assessed by en face quantification of the thoracic aorta and in cross-sections of the aortic root. Mean arterial pressure (MAP) was measured. AT1 and AT2 receptor expression were analysed using real-time polymerase chain reaction (PCR) and the localization of the AT2 receptor protein confirmed with immunohistochemistry. RESULTS Ang II infusion increased MAP only in mice on a standard diet (P < 0.001). Regardless of diet, Ang II-infused mice had 22-30 times increased plaque area in the thoracic aorta (P < 0.001 for both). Ang II had no effect on plaque in the aortic root. Plaque area was not affected by PD123319. AT2 receptor was heavily expressed in the plaques and increased six- to ninefold by a high cholesterol diet and Ang II infusion (P < 0.01). CONCLUSION Ang II increases the extent of atherosclerosis in ApoE mice. Despite up-regulation of the AT2 receptor, we found no support for an effect of the AT2 receptor on atherogenesis in this model.
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Affiliation(s)
- Maria E Johansson
- Department of Physiology, Institute of Physiology and Pharmacology, The Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
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18
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Takai S, Jin D, Sakaguchi M, Muramatsu M, Miyazaki M. The regressive effect of an angiotensin II receptor blocker on formed fatty streaks in monkeys fed a high-cholesterol diet. J Hypertens 2005; 23:1879-86. [PMID: 16148612 DOI: 10.1097/01.hjh.0000182527.52063.32] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To clarify the regressive effect of an angiotensin II type 1 receptor blocker (ARB) on already formed fatty streaks, we investigated the effect of the administration of an ARB, olmesartan, on formed fatty streaks in monkeys fed a high-cholesterol diet. METHODS After the monkeys were fed a high-cholesterol diet for 6 months, intimal hyperplasia was clearly observed on intravascular ultrasound. For the next 6 months, the high-cholesterol diet was continued, and olmesartan (3 mg/kg per day) or placebo was administered. A control group was fed a normal diet for 12 months. RESULTS Olmesartan did not significantly affect blood pressure or plasma cholesterol levels throughout the experiment. After 6 months of treatment with olmesartan, intimal hyperplasia was significantly lower than before treatment. Acetylcholine-induced relaxation in isolated carotid arteries was significantly less in the high-cholesterol diet placebo-treated group compared to the normal diet group, whereas its response was improved by olmesartan. Serum levels of monocyte chemoattractant protein were significantly increased with a high cholesterol load, but they were significantly suppressed by olmesartan. CONCLUSIONS We have demonstrated for the first time that an ARB, olmesartan, was found to have a regressive effect on formed fatty streaks in monkeys.
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Affiliation(s)
- Shinji Takai
- Department of Pharmacology, Osaka Medical College, Takatsuki City, Osaka, Japan.
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19
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Crook ED, Thallapureddy A, Migdal S, Flack JM, Greene EL, Salahudeen A, Tucker JK, Taylor HA. Lipid abnormalities and renal disease: is dyslipidemia a predictor of progression of renal disease? Am J Med Sci 2003; 325:340-8. [PMID: 12811230 DOI: 10.1097/00000441-200306000-00005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Dyslipidemia is a cardiovascular disease (CVD) risk factor that is associated with enhanced atherosclerosis and plaque instability. Renal insufficiency is associated with abnormalities in lipoprotein metabolism in both the early and the advanced stages of chronic renal failure. These include alterations in apolipoprotein A (apo A)- and B- containing lipoproteins, high-density lipoproteins, and triglycerides. In animal models, these alterations in lipid metabolism and action lead to macrophage activation and infiltration in the kidney with resultant tubulointerstitial and endothelial cell injury. Limited data in humans suggest that, in addition to contributing to CVD, dyslipidemia may be a risk factor for the progression of renal disease. The effects of dyslipidemia on the kidney are mainly observed in those with other risk factors for renal disease progression such as hypertension, diabetes, and proteinuria. Renal disease is a strong risk factor for CVD and African Americans have high rates of renal disease. Therefore, examining the effects of dyslipidemia on the development or progression or renal disease will be an important question for the Jackson Heart Study and is the topic of this review.
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Affiliation(s)
- Errol D Crook
- Department of Medicine, Wayne State University School of Medicine and John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan 48302, USA.
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20
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Takai S, Kim S, Sakonjo H, Miyazaki M. Mechanisms of angiotensin II type 1 receptor blocker for anti-atherosclerotic effect in monkeys fed a high-cholesterol diet. J Hypertens 2003; 21:361-9. [PMID: 12569267 DOI: 10.1097/00004872-200302000-00028] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To clarify the mechanism of the anti-atherosclerotic effect of angiotensin II type 1 receptor blocker (ARB) in primates, we investigated whether an ARB (CS-866) affects the serum markers of inflammation and growth factors, and the endothelial function in monkeys fed a high-cholesterol diet. DESIGN Monkeys fed a high-cholesterol diet for 6 months were divided into two groups: one group was given an ARB, CS-866 (10 mg/kg per day), and the other group was not. The control group was fed a normal diet. RESULTS Blood pressure and the plasma cholesterol level were not affected by CS-866. Plasma levels of angiotensin II, renin, angiotensin converting enzyme and chymase were not changed by the high-cholesterol diet, whereas vascular angiotensin converting enzyme, but not chymase, was significantly increased. Serum levels of macrophage-colony stimulating factor, transforming growth factor-beta1 and intracellular adhesion molecule-1 were significantly increased in monkeys fed a high-cholesterol diet but they were suppressed by CS-866. The relaxation response of isolated carotid arteries to acetylcholine was suppressed in the high-cholesterol group, whereas it was improved by CS-866. CONCLUSIONS CS-866 reduced lipid deposition along with the suppression of serum macrophage-colony stimulating factor, transforming growth factor-beta 1 and intracellular adhesion molecule-1, and the improvement of vascular functions, suggesting that ARB has multiple mechanisms for reducing lipid deposition in primates.
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Affiliation(s)
- Shinji Takai
- Department of Pharmacology, Osaka Medical College, Takatsuki City, Osaka, Japan.
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21
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Yan C, Kim D, Aizawa T, Berk BC. Functional interplay between angiotensin II and nitric oxide: cyclic GMP as a key mediator. Arterioscler Thromb Vasc Biol 2003; 23:26-36. [PMID: 12524221 DOI: 10.1161/01.atv.0000046231.17365.9d] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Angiotensin II (Ang II) and nitric oxide (NO) signaling pathways mutually regulate each other by multiple mechanisms. Ang II regulates the expression of NO synthase and NO production, whereas NO downregulates the Ang II type I (AT1) receptor. In addition, downstream effectors of Ang II and NO signaling pathways also interact with each other. A feedback mechanism between Ang II and NO is critical for normal vascular structure and function. Imbalance of Ang II and NO has been implicated in the pathophysiology of many vascular diseases. In this review, we focus on the diverse ways in which Ang II and NO interact and the importance of the balance between the signaling pathways activated by these mediators.
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Affiliation(s)
- Chen Yan
- Center for Cardiovascular Research, University of Rochester, Rochester, NY, USA
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22
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Ghosh S, Sica D, Schoolwerth AC, Quigg RJ, Haas M, Fakhry I, Gehr TWB. The role of the renin-angiotensin system in cholesterol and puromycin mediated renal injury. Am J Med Sci 2002; 324:296-304. [PMID: 12495295 DOI: 10.1097/00000441-200212000-00002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Puromycin aminonucleoside (PAN) nephropathy is a widely studied model of glomerular sclerosis (GS) in the rat, and cholesterol feeding exacerbates the injury induced by PAN. The importance of the interaction of angiotensin II (Ang II) with the AT2 receptor is unclear. We investigated the role of the renin-angiotensin system, particularly with regard to AT1 and AT2 receptor dynamics, in PAN and cholesterol-mediated GS. METHODS Sprague-Dawley rats were given a 4% cholesterol diet (group II), subcutaneous PAN (group III), or a 4% cholesterol diet and PAN (group IV) and compared with a control group given PAN vehicle (group I). After 16 weeks, kidneys were harvested and tissue Ang II concentration, angiotensin-converting enzyme (ACE) activity, and ACE, AT1, and AT2 mRNA levels were determined. RESULTS Compared with control rats, proteinuria was significantly higher in groups II to IV. Kidney ACE activity and ACE mRNA levels in groups III and IV were 2- and 3-fold higher than in groups I and II, respectively. Kidney Ang II concentration also was increased in the experimental groups. Whereas kidney AT1 mRNA was significantly lower in groups III and IV, kidney AT2 mRNA was significantly increased in groups II to IV. CONCLUSION In these experimental models of GS, there is significant activation of the tissue-based renin-angiotensin system. Puromycin with and without cholesterol decreased the AT1 receptor mRNA and increased the AT2 receptor mRNA. Up-regulation of AT2 receptors may be important in ameliorating the proliferative effects of Ang II, which presumably occur through the AT1 receptor.
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Affiliation(s)
- Siddhartha Ghosh
- Department of Internal Medicine, Division of Nephrology, Virginia Commonwealth University, Richmond, VA 23298, USA
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Hosoya K, Ishimitsu T. Protection of the cardiovascular system by imidapril, a versatile angiotensin-converting enzyme inhibitor. CARDIOVASCULAR DRUG REVIEWS 2002; 20:93-110. [PMID: 12177688 DOI: 10.1111/j.1527-3466.2002.tb00185.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Imidapril hydrochloride (imidapril) is a long-acting, non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor, which has been used clinically in the treatment of hypertension, chronic congestive heart failure (CHF), acute myocardial infarction (AMI), and diabetic nephropathy. It has the unique advantage over other ACE inhibitors in causing a lower incidence of dry cough. After oral administration, imidapril is rapidly converted in the liver to its active metabolite imidaprilat. The plasma levels of imidaprilat gradually increase in proportion to the dose, and decline slowly. The time to reach the maximum plasma concentration (T(max)) is 2.0 h for imidapril and 9.3 h for imidaprilat. The elimination half-lives (t(1/2)) of imidapril and imidaprilat is 1.7 and 14.8 h, respectively. Imidapril and its metabolites are excreted chiefly in the urine. As an ACE inhibitor, imidaprilat is as potent as enalaprilat, an active metabolite of enalapril, and about twice as potent as captopril. In patients with hypertension, blood pressure was still decreased at 24 h after imidapril administration. The antihypertensive effect of imidapril was dose-dependent. The maximal reduction of blood pressure and plasma ACE was achieved with imidapril, 10 mg once daily, and the additional effect was not prominent with higher doses. When administered to patients with AMI, imidapril improved left ventricular ejection fraction and reduced plasma brain natriuretic peptide (BNP) levels. In patients with mild-to-moderate CHF [New York Heart Association (NYHA) functional class II-III], imidapril increased exercise time and physical working capacity and decreased plasma atrial natriuretic peptide (ANP) and BNP levels in a dose-related manner. In patients with diabetic nephropathy, imidapril decreased urinary albumin excretion. Interestingly, imidapril improved asymptomatic dysphagia in patients with a history of stroke. In the same patients it increased serum substance P levels, while the angiotensin II receptor antagonist losartan was ineffective. These studies indicate that imidapril is a versatile ACE inhibitor. In addition to its effectiveness in the treatment of hypertension, CHF, and AMI, imidapril has beneficial effects in the treatment of diabetic nephropathy and asymptomatic dysphagia. Good tissue penetration and inhibition of tissue ACE by imidapril contributes to its effectiveness in preventing cardiovascular complications of hypertension. The major advantages of imidapril are its activity in the treatment of various cardiovascular diseases and lower incidence of cough compared with some of the older ACE inhibitors.
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Affiliation(s)
- Kazuyoshi Hosoya
- Department of Hypertension and Cardiorenal Medicine, Dokkyo University School of Medicine, Mibu, Tochigi, Japan
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24
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Abstract
PURPOSE OF REVIEW The concept that angiotensin II plays a central role in early atherogenesis, progression to atherosclerotic plaque, and the most serious clinical sequelae of coronary artery disease is the subject of considerable current interest. Results from recent large clinical trials confirm that blunting of the renin-angiotensin system through either angiotensin converting enzyme inhibition or angiotensin II type 1 receptor blockade incurs significant beneficial outcomes in patients with coronary artery disease. The exact mechanisms for these effects are not yet clear, but are suggested by studies demonstrating that suppression of the renin-angiotensin system is associated with muted vascular oxidative stress. RECENT FINDINGS As most of the biological effects of the renin-angiotensin system occur through stimulation of the angiotensin II type 1 receptor, the focus of this review is on changes in the vascular wall mediated by this receptor and primarily related to endothelial and vascular smooth muscle cells, monocyte/macrophages and platelets. The interactions between angiotensin II and nitric oxide exert particular demands on the vascular capacity to adapt to dyslipidemia, hypertension, estrogen deficiency and diabetes mellitus that appear to exacerbate atherogenesis. Associated with each of these conditions is angiotensin II-mediated stimulation of macrophages, platelet aggregation, plasminogen activator inhibitor 1, endothelial dysfunction, vascular smooth muscle cell proliferation and migration, apoptosis, leukocyte recruitment, fibrogenesis and thrombosis. SUMMARY Inhibition of the actions of angiotensin II serves a dual purpose: indirectly through reduction of mechanical stress on the vascular wall, and directly by diminished stimulation for vascular restructuring and remodeling. Collectively, data from studies published over the last year confirm and extend the notion that angiotensin II is a true cytokine prevalent at all stages of atherogenesis.
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Affiliation(s)
- William B Strawn
- Hypertension and Vascular Disease Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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25
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Wilfert K, Guski H, Persson PB, Stauss HM. Cardiovascular responses to angiotensin II in atherosclerosis. ACTA PHYSIOLOGICA SCANDINAVICA 2002; 176:95-100. [PMID: 12354168 DOI: 10.1046/j.1365-201x.2002.01025.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atherosclerosis is associated with increased angiotensin II AT1-receptor expression and vascular hyperresponsiveness to angiotensin II. Nevertheless, atherosclerosis is often not accompanied by hypertension. We studied if the hypertensive effect of angiotensin II is more pronounced in atherosclerosis. Rabbits were fed a high-cholesterol diet (n = 10) for 12 weeks, followed by a standard diet for another 6 weeks. Control animals received the standard diet (n = 8) for 18 weeks. After 18 weeks, haemodynamic measurements were performed during a baseline recording and during an intravenous infusion of angiotensin II (0.4 microg kg-1 min-1). Atherosclerosis in the high-cholesterol group was verified by histological and lipidchemical tissue examinations. During angiotensin II infusion, total peripheral resistance (TPR) increased more in the high-cholesterol group than in controls (+81.6 +/- 12.4 vs. +40.6 +/- 9.7 mmHg min L-1, P < 0.05). While cardiac output and stroke volume (SV) decreased more in the high-cholesterol group (P < 0.05), reflex bradycardia was stronger in the control group (P < 0.05), indicating a reduced baroreceptor reflex sensitivity in atherosclerosis. Despite the larger increase in TPR and the reduced baroreceptor reflex sensitivity in the high-cholesterol group, maximum blood pressure response to angiotensin II was similar in both groups. The lack of a greater blood pressure response to angiotensin II in the high-cholesterol group could be the result of the early stages of heart failure. Under resting conditions, heart failure seems to be fully compensated, as baseline haemodynamic parameters were similar in the high-cholesterol group and in controls. However, during angiotensin II infusion, the compensatory mechanisms do not prevent a stronger fall in cardiac output and SV. Therefore, the blood pressure response to angiotensin II is not exaggerated in atherosclerotic animals, as vascular hyperresponsiveness to angiotensin II is opposed by the stronger fall in cardiac output and SV.
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Affiliation(s)
- K Wilfert
- Johannes-Müller-Institut für Physiologie, Charité, Humboldt-Universität zu Berlin, Berlin, Germany
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26
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Abstract
The possible inhibition of lipid deposition into vascular tissues by a novel angiotensin II type 1 receptor antagonist, olmesartan, was investigated in a primate high-cholesterol model. Twelve monkeys that were fed a high-cholesterol (4% cholesterol and 6% corn oil) diet for 6 months were divided into two groups: one group was given olmesartan medoxomil (10 mg/kg per day), and the other group was given no medication. A further control group of six monkeys was fed a normal diet throughout the study. The level of low-density lipoprotein (LDL) cholesterol was increased by the high-cholesterol diet, whereas that of high-density lipoprotein (HDL) cholesterol was decreased. Olmesartan decreased the areas of lipid deposition on the aortic surface and intimal cross-section area, but not the mean blood pressure and the levels of LDL and HDL cholesterol. The relaxation response of isolated carotid arteries to acetylcholine was suppressed in the high-cholesterol group, but this was improved by olmesartan. Olmesartan inhibited the accumulation of macrophages in the intimal layer. Serum levels of transforming growth factor (TGF)-beta1, macrophage colony-stimulating factor (M-CSF) and intracellular adhesion molecule (ICAM)-1 were increased in monkeys fed the high-cholesterol diet, but they were suppressed by olmesartan, although the decrease was not significant. Olmesartan reduced lipid deposition, accompanied by the improvement of vascular functions and the inhibition of macrophage accumulation in the intimal layer and showed a trend towards the suppression of serum TGF-beta1, M-CSF and ICAM-1.
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Affiliation(s)
- M Miyazaki
- Department of Pharmacology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki City, Osaka 569-8686, Japan.
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27
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Ortlepp JR, Breuer J, Eitner F, Kluge K, Kluge R, Floege J, Hollweg G, Hanrath P, Joost HG. Inhibition of the renin-angiotensin system ameliorates genetically determined hyperinsulinemia. Eur J Pharmacol 2002; 436:145-50. [PMID: 11834258 DOI: 10.1016/s0014-2999(01)01587-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study was performed in order to assess the potentially different effects of the angiotensin-converting enzyme inhibitor captopril and of the angiotensin II receptor antagonist irbesartan on the metabolic syndrome in an animal model. Male NZO/BL6 F1 mice were treated with captopril, irbesartan, or placebo for 10 months: Control animals treated with placebo developed a metabolic syndrome with obesity (55.5+/-6.3 g), hypertension (146+/-10 mm Hg), hyperinsulinemia (7.2+/-5.7 ng/ml), hypercholesterolemia (5.1+/-0.7 mmol/l), cardiac hypertrophy (269+/-44 mg) and atherosclerotic plaques in the ascending aorta (3.6+/-1.5 microm(2)). Treatment with angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonist significantly (p<0.001) reduces hypertension (73+/-5 and 78+/-11 mm Hg), cardiac hypertrophy (203+/-26 and 202+/-18 mg) and atherosclerosis (2.2+/-0.9 and 1.8+/-0.8 microm(2)). In addition, they prevented the development of obesity (42.2+/-3.5 and 38.3+/-2.8 g) and hyperinsulinemia (3.6+/-1.5 and 1.8+/-0.4 ng/ml). In conclusion, long-term treatment with an angiotensin-converting enzyme inhibitor or an angiotensin II receptor antagonist can ameliorate obesity and hyperinsulinemia in a genetically determined mouse model.
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Affiliation(s)
- J R Ortlepp
- Medical Clinic I, University Hospital of Aachen, Pauwelsstrasse 30, 52057, Aachen, Germany.
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28
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Dell'Italia LJ, Rocic P, Lucchesi PA. Use of angiotensin-converting enzyme inhibitors in patients with diabetes and coronary artery disease. Curr Probl Cardiol 2002; 27:6-36. [PMID: 11815752 DOI: 10.1067/mcd.2002.121580] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Louis J Dell'Italia
- Birmingham Veteran Affairs Medical Center, Department of Medicine, University of Alabama at Birmingham, USA
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29
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Nishimoto M, Takai S, Kim S, Jin D, Yuda A, Sakaguchi M, Yamada M, Sawada Y, Kondo K, Asada K, Iwao H, Sasaki S, Miyazaki M. Significance of chymase-dependent angiotensin II-forming pathway in the development of vascular proliferation. Circulation 2001; 104:1274-9. [PMID: 11551879 DOI: 10.1161/hc3601.094304] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Vascular tissues of humans and dogs contain chymase as an angiotensin II-forming enzyme. In this study, we investigated whether chymase-dependent angiotensin II formation plays a crucial role in the development of vascular proliferation in dog grafted veins. METHODS AND RESULTS The right external jugular vein of dogs was grafted to the ipsilateral carotid artery. As a control group, the right external jugular veins in dogs that had not received grafts were used. In the chymase inhibitor-treated group, the vein was infiltrated with 10 micromol/L Suc-Val-Pro-Phe(P)(OPh)(2) and was grafted to the carotid artery. In the placebo-treated group, ACE activity in the grafted veins was significantly lower than that in the control veins up to 7 days after the operation, whereas chymase activity was increased significantly. After 7 days, the mRNA levels of collagen I, collagen III, and fibronectin, all of which are induced by an increase of angiotensin II action, were significantly increased in the grafted veins, and the intima-media ratio of the grafted veins was also increased. In the chymase inhibitor-treated group, the chymase activity in the grafted veins 7 days after the operation was suppressed to 12.1%. The elevated mRNA levels of fibronectin, collagen I, and collagen III in the grafted veins were significantly suppressed by treatment with the chymase inhibitor, and the intima-media ratio was also decreased significantly. CONCLUSIONS We demonstrate for the first time that chymase-dependent angiotensin II formation plays an important role in the development of vascular proliferation in the grafted veins.
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Affiliation(s)
- M Nishimoto
- Department of Pharmacology, Osaka Medical College, Osaka City University Medical School, Osaka, Japan
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30
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Affiliation(s)
- J Menard
- Faculté de Médecine, Université Paris, 75270 Paris, France
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31
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Miyazaki M, Takai S. Local angiotensin II-generating system in vascular tissues: the roles of chymase. Hypertens Res 2001; 24:189-93. [PMID: 11409639 DOI: 10.1291/hypres.24.189] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Roles of each angiotensin II producing enzymes of each of the angiotensin II-producing enzymes were reviewed based on experimental models. In vascular tissues, angiotensin II is potentially cleaved from angiotensin I by angiotensin converting enzyme (ACE) and chymase. It has been confirmed that vascular tissues of humans, monkeys, dogs and hamsters have a chymase-dependent angiotensin II-forming pathway. Much like other hypertensive models, hamster hypertensive models show high levels of vascular ACE activity, but not chymase activity. In hypertensive hamsters, administration of either an ACE inhibitor or an angiotensin II type 1 (AT1) receptor antagonist resulted in similar reductions in blood pressure, suggesting that chymase is not involved in the maintenance of high blood pressure in this model. In monkeys fed a high-cholesterol diet, ACE activity was increased in the atherosclerotic lesions, and an ACE inhibitor and an AT1 receptor antagonist prevented atherosclerosis to a similar degree, suggesting that ACE may be mainly involved in the development of atherosclerosis. After balloon injury in dog vessels, both ACE and chymase activities were locally increased about 3-fold in the injured arteries, and an AT1 receptor antagonist was effective in preventing the intimal formation, but an ACE inhibitor was ineffective. In dog grafted veins, the activities of chymase were increased 15-fold, but those of ACE were increased only 2-fold, and the intimal formation was suppressed by either an AT1 receptor antagonist or a chymase inhibitor. In the normal vascular tissues, ACE plays a crucial role for angiotensin II production, whereas chymase is stored in mast cells in an inactive form. Chymase acquires the ability to form angiotensin II following mast cells activation followed by mast cells activation by a strong stimulus such as occurs in catheter-injury or grafting. Together, these results indicate that chymase plays a major role in the vascular angiotensin II-generating system, particularly in cases of vascular injury.
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Affiliation(s)
- M Miyazaki
- Department of Pharmacology, Osaka Medical College, Takatsuki, Japan.
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Abstract
CS-866 is a new angiotensin II receptor blocker that has demonstrated effectiveness for lowering blood pressure in animal models of hypertension. Given the proposed involvement of the renin-angiotensin system in diabetic nephropathy and atherosclerosis, we have tested CS-866 in animal models of these conditions. The renal protective properties of CS-866 were examined in the Zucker diabetic fatty (ZDF) rat, a model of type 2 diabetes that develops progressive hyperglycemia, glomerulosclerosis, and proteinuria. Treatment of ZDF rats with CS-866 in the diet for 19 weeks resulted in a dose-dependent reduction in urinary protein excretion compared with vehicle-treated control rats, which was independent of changes in blood pressure and glycemic state. The antiatherosclerotic properties of CS-866 were tested in 2 animal models. In the first study, cynomolgus monkeys were fed a high-cholesterol diet for 6 months while receiving CS-866 or vehicle. At the end of this period, CS-866-treated animals had 64% less plaque area in the aorta than controls. CS-866 was also tested in the Watanabe heritable hyperlipidemic (WHHL) rabbit model of atherosclerosis. WHHL rabbits were treated for 32 weeks with CS-866 (1 mg/kg), pravastatin (50 mg/kg), a combination of the 2 drugs, or vehicle. CS-866 had no effect on plasma cholesterol levels and reduced blood pressures minimally. Pravastatin alone reduced serum cholesterol but had no effect on blood pressure or lesion area. In contrast, treatment with CS-866 resulted in a 40% reduction in lesion area compared with vehicle-treated control when given alone and a 50% reduction in combination with pravastatin. On the basis of results from animal models, CS-866 may be a useful treatment for diabetic nephropathy and atherosclerosis.
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Affiliation(s)
- H Koike
- Pharmacology and Molecular Biology Research Laboratories, Sankyo Company, Limited, Tokyo, Japan
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Nishimoto M, Takai S, Sawada Y, Yuda A, Kondo K, Yamada M, Jin D, Sakaguchi M, Asada K, Sasaki S, Miyazaki M. Chymase-dependent angiotensin II formation in the saphenous vein versus the internal thoracic artery. J Thorac Cardiovasc Surg 2001; 121:729-34. [PMID: 11279415 DOI: 10.1067/mtc.2001.112467] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES The great saphenous vein graft is known to be less patent than the internal thoracic artery graft. Recently, we reported that chymase-dependent angiotensin II formation plays an important role in the development of intimal hyperplasia in dog grafted veins. In this study we investigated the levels of angiotensin II-forming enzymes, angiotensin-converting enzyme, and chymase in human saphenous veins and internal thoracic arteries. METHODS The saphenous vein and internal thoracic artery specimens were obtained from coronary artery bypass grafts of patients during surgical procedures (saphenous vein, n = 16; internal thoracic artery, n = 16). Activities of angiotensin-converting enzyme and chymase were determined by using the extract from the saphenous vein or internal thoracic artery. Sections of the saphenous vein or internal thoracic artery were stained with van Gieson's elastin stain and were immunostained with anti-human chymase antibody. RESULTS The activities of angiotensin-converting enzyme in the saphenous vein and internal thoracic artery were 0.34 +/- 0.12 and 0.32 +/- 0.17 mU/mg protein, respectively, and the difference was not significant. The chymase activity in the saphenous vein was significantly higher than that in the internal thoracic artery (saphenous vein, 10.1 +/- 0.81 mU/mg protein; internal thoracic artery, 6.21 +/- 1.86 mU/mg protein). Chymase-positive cells in the saphenous vein were located in both the media and adventitia, and those in the internal thoracic artery were located only in the adventitia. The number of chymase-positive cells in the saphenous vein was about 2.6 times that in the internal thoracic artery. CONCLUSION The chymase activity, but not the angiotensin-converting enzyme activity, was significantly higher in the saphenous vein, suggesting that the high levels of chymase activity may be related to the poorer performance of the saphenous vein for use as a bypass conduit.
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Affiliation(s)
- M Nishimoto
- Department of Pharmacology and the Department of Thoracic and Cardiovascular Surgery, Osaka Medical College, 2-7 Daigaku-cho, Takatsuki City, Osaka, Japan
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34
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Abstract
Acute coronary syndromes are caused by plaque rupture. The conventional strategy of prevention of plaque rupture has been driven by the "lipid hypothesis"--if lipid levels are optimized to target levels, the risk of coronary events is decreased. Indeed, the hypothesis has been validated by the dramatic success of statin therapy. However, further major reductions in cardiac events is a realistic goal; various mechanistic and small clinical studies show that statins have beneficial effects in addition to their lipid-lowering properties. One of these beneficial effects is stabilization of plaque. Despite billions of dollars spent on randomized clinical trials, optimal therapy for coronary artery disease is yet to be tested. This therapy might include various combinations of the Mediterranean or low-fat diet, endothelial passivation, lipid-lowering drugs, antioxidants, antiplatelet agents and anti-inflammatory agents.
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Affiliation(s)
- J S Forrester
- Division of Cardiology, Cedars-Sinai Medical Center, and the University of California Los Angeles School of Medicine, 90048, USA
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35
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Schmidt-Ott KM, Kagiyama S, Phillips MI. The multiple actions of angiotensin II in atherosclerosis. REGULATORY PEPTIDES 2000; 93:65-77. [PMID: 11033054 DOI: 10.1016/s0167-0115(00)00178-6] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Angiotensin II (Ang II), the effector peptide of the renin-angiotensin system, has been implied in the pathogenesis of atherosclerosis on various levels. There is abundant experimental evidence that pharmacological antagonism of Ang II formation by angiotensin converting enzyme inhibition or blockade of the cellular effects of Ang II by angiotensin type 1 receptor blockade inhibits formation and progression of atherosclerotic lesions. Angiotensin promotes generation of oxidative stress in the vasculature, which appears to be a key mediator of Ang II-induced endothelial dysfunction, endothelial cell apoptosis, and lipoprotein peroxidation. Ang II also induces cellular adhesion molecules, chemotactic and proinflammatory cytokines, all of which participate in the induction of an inflammatory response in the vessel wall. In addition, Ang II triggers responses in vascular smooth muscle cells that lead to proliferation, migration, and a phenotypic modulation resulting in production of growth factors and extracellular matrix. While all of these effects contribute to neointima formation and development of atherosclerotic lesions, Ang II may also be involved in acute complications of atherosclerosis by promoting plaque rupture and a hyperthrombotic state. Accordingly, Ang II appears to have a central role in the pathophysiology of atherosclerosis.
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Affiliation(s)
- K M Schmidt-Ott
- Department of Physiology, College of Medicine, Box 100274, University of Florida, 32610, Gainesville, FL, USA
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36
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Strawn WB, Chappell MC, Dean RH, Kivlighn S, Ferrario CM. Inhibition of early atherogenesis by losartan in monkeys with diet-induced hypercholesterolemia. Circulation 2000; 101:1586-93. [PMID: 10747353 DOI: 10.1161/01.cir.101.13.1586] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Angiotensin II may contribute to atherogenesis by facilitating the proliferative and inflammatory response to hypercholesterolemia. This study determined, in a primate model of diet-induced atherosclerosis, the effect of AT(1) blockade on fatty-streak formation, plasma lipids, and surrogate markers of vascular injury. METHODS AND RESULTS Male cynomolgus monkeys fed a diet containing 0.067 mg cholesterol/kJ for 20 weeks were given losartan (180 mg/d, n=6) or vehicle (n=8) for 6 weeks starting at week 12 of the dietary regimen. Arterial pressure, heart rate, plasma total and lipoprotein cholesterol concentrations, and lipoprotein particle sizes and subclass distributions were unaffected by treatment. Losartan caused significant (P<0.05) increases in plasma angiotensin II and angiotensin-(1-7). Compared with vehicle-treated controls, losartan reduced the extent of fatty streak in the aorta, the coronary arteries, and the carotid arteries by approximately 50% (P<0.05). A significant (P<0.05) reduction in the susceptibility of LDL to in vitro oxidation, serum levels of monocyte chemoattractant protein-1, and circulating monocyte CD11b expression were also associated with losartan treatment. In addition, serum levels of vascular cell adhesion molecule-1 and E-selectin did not change during treatment but increased after discontinuation of losartan. Serum C-reactive protein, platelet aggregability, and white cell counts were not modified by losartan. CONCLUSIONS This study demonstrates for the first time an antiatherogenic effect of AT(1) receptor blockade in nonhuman primates. Losartan inhibited fatty-streak formation through mechanisms that may include protection of LDL from oxidation and suppression of vascular monocyte activation and recruitment factors.
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Affiliation(s)
- W B Strawn
- Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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37
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Wilfert K, Drischel K, Unbehaun A, Guski H, Persson PB, Stauss HM. Vascular response to angiotensin II in atherosclerosis: role of the baroreflex. Hypertension 2000; 35:685-90. [PMID: 10679518 DOI: 10.1161/01.hyp.35.2.685] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High-cholesterol alimentation is associated with an induction of angiotensin-converting enzyme and angiotensin II receptor expression within the vascular wall of the aorta. Despite an enhanced pressure response to angiotensin II in atherosclerotic conscious rabbits, angiotensin II-induced contraction was reduced in isolated vascular rings from the aorta and unchanged in those from the iliac artery. We, therefore, investigated whether cholesterol-induced atherosclerosis enhances overall vascular responsiveness to angiotensin II in intact animals and whether an altered arterial baroreflex sensitivity can explain the discrepancy between experiments in intact animals and isolated blood vessels. Rabbits were maintained on a high-cholesterol diet (2 g/d cholesterol plus 20 mL/d sunflower seed oil, n=11) or on a standard diet (n=12) for 12 weeks. Total serum lipids markedly increased (P<0.05). Tissue examinations 6 weeks after termination of the high-cholesterol diet revealed distinct atherosclerosis and elevated cholesterol content in the aorta (P<0.05). A high-cholesterol diet did not change baseline hemodynamic parameters. However, angiotensin II-induced increases in total peripheral resistance were larger in the atherosclerotic animals (86.3+/-13.0 versus 41.9+/-9.7 mm Hg. L(-1). min, P<0.05). In addition, the blood pressure pulse interval relationship was markedly reduced (slope: 0.80+/-0.14 versus 0. 49+/-0.06 ms/mm Hg, P<0.05), which suggested that the baroreflex blunted the angiotensin II response to a lesser extent in atherosclerotic animals. In conclusion, the overall vascular responsiveness to angiotensin II is increased in the atherosclerotic rabbit as indicated by the larger increase in total peripheral resistance. An attenuation of the arterial baroreflex sensitivity may contribute to this effect.
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Affiliation(s)
- K Wilfert
- Johannes-Müller-Institut für Physiologie, Berlin, Germany
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38
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Uehara Y, Urata H, Sasaguri M, Ideishi M, Sakata N, Tashiro T, Kimura M, Arakawa K. Increased chymase activity in internal thoracic artery of patients with hypercholesterolemia. Hypertension 2000; 35:55-60. [PMID: 10642275 DOI: 10.1161/01.hyp.35.1.55] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Apart from ACE, various angiotensin II (Ang II)-forming serine proteinases (eg, chymase, kallikrein, and cathepsin G) are known to exist in human tissues, but their clinical significance or the regulatory mechanisms that control their activities are not well established. A recent clinical study has shown that chymase activity was significantly increased in human atherosclerotic or aneurysmal aorta. The association between vascular Ang II-forming activities (AIIFAs) in the human internal thoracic artery (ITA) and various clinical parameters was studied with the use of ITAs obtained from 32 patients who underwent coronary artery bypass graft surgery. Total and ACE- and chymase-dependent AIIFAs in homogenates of ITAs were determined. Total AIIFA was 8.67+/-0.86 (nmol Ang II formed. min(-1). mg protein(-1) [U]), and approximately 95% of the activities were due to chymase. Serum total cholesterol level, but no other risk factors, significantly correlated with chymase- (r=0. 60, P<0.001) and ACE- (r=0.35, P<0.05) dependent AIIFAs, respectively. LDL cholesterol level was also correlated with chymase-dependent AIIFAs (r=0.47, P<0.05). Mast cells identified through the use of toluidine blue or immunohistochemical staining appeared in the adventitia but not in the intima or media of ITAs. Our results suggest that an increased plasma LDL cholesterol level may induce increased arterial chymase and ACE activity.
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Affiliation(s)
- Y Uehara
- Department of Internal Medicine, School of Medicine, Fukuoka University, Fukuoka, Japan
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39
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Takeda K, Ichiki T, Funakoshi Y, Ito K, Takeshita A. Downregulation of angiotensin II type 1 receptor by all-trans retinoic acid in vascular smooth muscle cells. Hypertension 2000; 35:297-302. [PMID: 10642314 DOI: 10.1161/01.hyp.35.1.297] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
All-trans retinoic acid (atRA) is a biologically active metabolite of vitamin A that plays an important role in cell differentiation and proliferation. Although neointimal formation after balloon injury of rat carotid artery is inhibited by atRA, the mechanisms are not clearly understood. Because the renin-angiotensin system is one of the crucial components of atherosclerosis, we examined the effects of atRA on the expression of angiotensin II type 1 receptor (AT(1)-R) in vascular smooth muscle cells. atRA (1 micromol/L) decreased the AT(1)-R mRNA level by 50% after 24 hours; AT(1)-R number was also reduced to the same extent after 48 hours. atRA markedly suppressed promoter activity of the AT(1)-R promoter-luciferase construct, but AT(1)-R mRNA stability was not affected. Cycloheximide blocked the atRA-induced decrease in AT(1)-R mRNA expression, suggesting that this process requires de novo protein synthesis. Simultaneous treatment with an agonist (Ro40-6055) specific for retinoic acid receptor (RAR) and an agonist (Ro25-7836) specific for retinoid X receptor (RXR) suppressed the AT(1)-R mRNA expression comparable to that with treatment with atRA, suggesting that the RAR/RXR heterodimer mediates the effect of atRA in AT(1)-R downregulation. These results suggest that atRA suppressed AT(1)-R mRNA transcription through new protein synthesis induced by RAR/RXR-dependent transcription. This study provides novel insight into a role of atRA as an important molecule that regulates AT(1)-R gene expression and provides possible mechanisms for the suppression of neointimal formation by atRA.
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MESH Headings
- Animals
- Antineoplastic Agents/pharmacology
- Aorta, Thoracic/cytology
- Benzoates/pharmacology
- Binding, Competitive/genetics
- CREB-Binding Protein
- Cells, Cultured
- Cycloheximide/pharmacology
- Down-Regulation/drug effects
- Gene Expression Regulation/drug effects
- Lac Operon
- Luciferases/genetics
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Nuclear Proteins/metabolism
- Promoter Regions, Genetic/physiology
- Protein Synthesis Inhibitors/pharmacology
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/genetics
- Receptors, Retinoic Acid/physiology
- Recombinant Fusion Proteins/genetics
- Retinoid X Receptors
- Tetrahydronaphthalenes/pharmacology
- Trans-Activators/metabolism
- Transcription Factors/physiology
- Tretinoin/pharmacology
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Affiliation(s)
- K Takeda
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Higashi-ku, Fukuoka, Japan
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40
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Usui M, Egashira K, Kitamoto S, Koyanagi M, Katoh M, Kataoka C, Shimokawa H, Takeshita A. Pathogenic role of oxidative stress in vascular angiotensin-converting enzyme activation in long-term blockade of nitric oxide synthesis in rats. Hypertension 1999; 34:546-51. [PMID: 10523324 DOI: 10.1161/01.hyp.34.4.546] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inhibition of nitric oxide (NO) synthesis with N(omega)-nitro-L-arginine methyl ester (L-NAME) activates vascular angiotensin-converting enzyme (ACE) and causes oxidative stress. We investigated the role of oxidative stress in the pathogenesis of ACE activation in rats. Studies involved aortas of rats receiving no treatment, L-NAME, L-NAME plus L-arginine, or L-NAME plus an antioxidant drug (N-acetylcysteine, allopurinol, or ebselen) for 7 days. L-NAME significantly increased oxidative stress (O(2)(-)) and ACE activity. The increased O(2)(-) production was normalized by removal of endothelium. Immunohistochemistry showed the increased ACE activity in the endothelial layer. Treatment with antioxidant drugs did not affect the L-NAME-induced increase in systolic arterial pressure but did prevent increases in vascular O(2)(-) production and ACE activity. These results implicate oxidative stress in the pathogenesis of vascular ACE activation in rats with long-term inhibition of NO synthesis. The observed effects of antioxidant drugs on ACE activation do not appear to involve the hypertension induced by L-NAME.
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Affiliation(s)
- M Usui
- Research Institute of Angiocardiology and Cardiovascular Clinic, Kyushu University Faculty of Medicine, Fukuoka, Japan
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41
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Miyazaki M, Sakonjo H, Takai S. Anti-atherosclerotic effects of an angiotensin converting enzyme inhibitor and an angiotensin II antagonist in Cynomolgus monkeys fed a high-cholesterol diet. Br J Pharmacol 1999; 128:523-9. [PMID: 10516628 PMCID: PMC1571675 DOI: 10.1038/sj.bjp.0702833] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We investigated the relationship between angiotensin II formation and the development of atherosclerotic lesions in the aorta of monkeys (Macaca fascicularis) fed a high-cholesterol (4% cholesterol and 6% corn oil) diet for 6 months, and studied the effects of an angiotensin converting enzyme (ACE) inhibitor, trandolapril (10 mg kg-1 per day, p.o.), and an angiotensin II type 1 receptor antagonist, 2-butyl-4-(methylthio)-1-[[2'[[[(propylamino)carbonyl]amino]sulfonyl] (1,1'-biphenyl)-4-yl]methyl]-1H-imidazole-5-carboxylate (HR 720; 20 mg kg-1 per day, p.o.). 2. The level of low-density lipoprotein was significantly increased by the cholesterol diet, whereas that of high-density lipoprotein was significantly decreased. The relative areas of the atherosclerotic lesions in the thoracic aorta in the normal and cholesterol-diet groups were 1.3+/-0.3 and 64+/-10%, respectively. 3. Plasma renin and ACE activities showed no differences between the normal and cholesterol-diet groups. ACE activity and the concentration of angiotensin II were significantly increased in the aorta of the cholesterol-fed monkeys. 4. Trandolapril and HR 720 decreased significantly the area of the atherosclerotic lesions in the thoracic aorta of cholesterol-fed monkeys, but not the mean blood pressure and the levels of low-density and high-density lipoproteins. 5. In plasma and aorta, trandolapril, but not HR 720, decreased significantly the ACE activities in the cholesterol-fed monkeys, while both of these drugs decreased significantly the angiotensin II levels. 6. In conclusion, blockade of angiotensin II function in vascular tissues by trandolapril or HR 720 may play an important role in preventing the development of atherosclerotic lesions.
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Affiliation(s)
- M Miyazaki
- Department of Pharmacology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki City, Osaka 569-8686, Japan
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42
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Bult H, Herman AG, Matthys KE. Antiatherosclerotic activity of drugs in relation to nitric oxide function. Eur J Pharmacol 1999; 375:157-76. [PMID: 10443573 DOI: 10.1016/s0014-2999(99)00328-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Many studies have shown that loss of endothelium-derived nitric oxide is a major factor of ischemic episodes in patients with coronary artery disease and there is increasing evidence to suggest that nitric oxide might exert antiatherosclerotic actions. Based on these concepts, the results of animal studies on the effects of lipid lowering drugs, antioxidants, angiotensin converting enzyme inhibitors, Ca2+ channel blockers, estrogens and agents which modulate nitric oxide bioavailability are presented and compared to the results of patient studies and clinical trials. In spite of encouraging results obtained with antioxidants in animals, clinical trials could only show a clear positive effect of vitamin E treatment on the outcome of cardiovascular disease. Angiotensin converting enzyme inhibitors can ameliorate endothelial dysfunction in coronary heart disease, but their impact on disease progression remains unclear. There is evidence that estrogen replacement therapy in post-menopausal women may increase the bioavailability of nitric oxide. Finally, improved endothelial function and plaque stability clearly contribute to the clinical benefits of lipid lowering interventions, statins in particular. Taken together, these studies lend support to the concept that improving endothelial function and nitric oxide release might serve as valuable elements in the prevention or therapy of cardiovascular disease.
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Affiliation(s)
- H Bult
- Department of Medicine, University of Antwerp (UIA), Belgium.
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