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Michel MC, Brunner HR, Foster C, Huo Y. Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease. Pharmacol Ther 2016; 164:1-81. [PMID: 27130806 DOI: 10.1016/j.pharmthera.2016.03.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 03/30/2016] [Indexed: 02/07/2023]
Abstract
We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.
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Affiliation(s)
- Martin C Michel
- Dept. Pharmacology, Johannes Gutenberg University, Mainz, Germany; Dept. Translational Medicine & Clinical Pharmacology, Boehringer Ingelheim, Ingelheim, Germany.
| | | | - Carolyn Foster
- Retiree from Dept. of Research Networking, Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT, USA
| | - Yong Huo
- Dept. Cardiology & Heart Center, Peking University First Hospital, Beijing, PR China
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Foundations of Pharmacotherapy for Heart Failure With Reduced Ejection Fraction: Evidence Meets Practice, Part I. J Cardiovasc Nurs 2015; 31:101-13. [PMID: 26296245 DOI: 10.1097/jcn.0000000000000284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pharmacologic treatment for systolic heart failure, otherwise known as heart failure with reduced ejection fraction, has been established through clinical trials and is formulated into guidelines to standardize the diagnosis and treatment. The premise of pharmacologic therapy in heart failure with reduced ejection fraction is aimed primarily at interrupting the neurohormonal cascade that is responsible for altering left ventricular shape and function. This is the first in a series of articles to describe the pharmacologic agents in the guidelines that impact the morbidity and mortality associated with heart failure. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and vasodilators will be presented in the context of the mechanism of action in heart failure, investigational trials that showed beneficial effects, and the practical application for clinical use.
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Guo X, Saini HK, Wang J, Gupta SK, Goyal RK, Dhalla NS. Prevention of remodeling in congestive heart failure due to myocardial infarction by blockade of the renin–angiotensin system. Expert Rev Cardiovasc Ther 2014; 3:717-32. [PMID: 16076281 DOI: 10.1586/14779072.3.4.717] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ventricular remodeling subsequent to myocardial infarction (MI) is a complex process and is considered to be a major determinant of the clinical course of congestive heart failure (CHF). Emerging evidence suggests that activation of the renin-angiotensin system (RAS) plays an important role in post-MI ventricular remodeling; however, it is becoming clear that this is one of several neurohumoral systems that are activated in CHF. Blockade of RAS by angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists attenuates the ventricular dysfunction, but the effects of individual drugs in reducing the morbidity and mortality in CHF patients are variable. Furthermore, there is a difference of opinion as to the time of initiation of therapy with RAS blockers after the onset of MI. Since blockade of RAS partially improves cardiac function, it is suggested that a combination therapy involving RAS blockers (angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists) and agents that affect other neurohumoral systems may prove useful for improved treatment of CHF. Although activation of RAS has been shown to promote oxidative stress in experimental studies, the use of antioxidant therapy in CHF patients is controversial. Recent experimental studies have shown that ventricular remodeling in CHF is associated with remodeling of subcellular organelles such as sarcolemma, sarcoplasmic reticulum, myofibrils and extracellular matrix in terms of their molecular structure and composition. Since attenuation of remodeling in one and/or more subcellular organelles by different agents may prevent the progression of CHF, it is a challenge to develop specific drugs affecting molecular mechanisms associated with subcellular remodeling for the improved therapy of CHF.
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Affiliation(s)
- Xiaobing Guo
- University of Manitoba, Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, Faculty of Medicine, Winnipeg, Canada
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Saleem TSM, Bharani K, Gauthaman K. ACE inhibitors - angiotensin II receptor antagonists: A useful combination therapy for ischemic heart disease. Open Access Emerg Med 2010; 2:51-9. [PMID: 27147838 PMCID: PMC4806827 DOI: 10.2147/oaem.s10507] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Morbidity and mortality from cardiovascular diseases are still high, even with the use of the best available therapies. There is mounting evidence that excessive renin-angiotensin system activation triggers much of the damaging and progressive nature of cardiovascular and kidney diseases through expression of angiotensin II. Moreover, angiotensin II play a major role in the development of end organ damage through a variety of inflammatory mechanisms. Today, angiotensins-converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists have clearly demonstrated their efficacy in preventing target organ damage and in reducing cardiovascular morbidity and mortality in ischemic heart disease (IHD). Moreover, the development of angiotensin II receptor antagonists has enabled a large gain in tolerability and safety. Several clinical trials have firmly established that these drugs act on the renin–angiotensin system, reducing the incidence of coronary events with monotherapy and combination therapy. In this review we summarize the role mono- and combined therapy of ACE inhibitors and angiotensin II receptor antagonists play in ischemic heart disease. In this respect the review will improve ideas for developing new formulations with combinations of these drugs in the future.
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Affiliation(s)
- T S Mohamed Saleem
- Department of Pharmacology, Annamacharya College of Pharmacy, Rajampet-516126, Kadapa Dist, Andhra Pradesh, India
| | - K Bharani
- Department of Pharmacology, Annamacharya College of Pharmacy, Rajampet-516126, Kadapa Dist, Andhra Pradesh, India
| | - K Gauthaman
- Department of Drug Technology, Higher Institute of Medical Technology, Derna, Libya
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De Arcangelis V, Soto D, Xiang Y. Phosphodiesterase 4 and phosphatase 2A differentially regulate cAMP/protein kinase a signaling for cardiac myocyte contraction under stimulation of beta1 adrenergic receptor. Mol Pharmacol 2008; 74:1453-62. [PMID: 18703669 DOI: 10.1124/mol.108.049718] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of the beta adrenergic receptor (betaAR) induces a tightly controlled cAMP/protein kinase A (PKA) activity to ensure an agonist dose-dependent and saturable contraction response in animal heart. We have found that stimulation of beta(1)AR by isoproterenol induces maximal contraction responses at the dose of 1 microM in cardiac myocytes; however, cAMP accumulation continues to increase with higher agonist concentrations. Dose-dependent cAMP accumulation is tightly controlled by negative regulator phosphodiesterase 4 (PDE4) that hydrolyzes cAMP. At 1 nM isoproterenol, cAMP accumulation is minimal because of the hydrolysis of cAMP by PDE4, which leads to a small increase in PKA phosphorylation of phospholamban and troponin I (TnI), and contraction responses. Inhibition of PDE4 activity with rolipram enhances cAMP accumulation, yields maximal PKA phosphorylation of phospholamban and TnI, and myocyte contraction responses. In contrast, at 10 microM isoproterenol, despite the negative effect of PDE4, cAMP accumulation is sufficient for maximal PKA phosphorylation of phospholamban and TnI. Inhibition of PDE4 with rolipram enhances cAMP accumulation, but not PKA phosphorylation and contraction responses. It is interesting that activities of both PKA and protein phosphatase 2A (PP2A) are enhanced under beta(1)AR activation with 10 microM isoproterenol, and PP2A is recruited to PKA/A kinase-anchoring protein complex. Inhibition of PP2A with okadaic acid further enhances the phosphorylation of phospholamban and TnI as well as contraction responses induced by 10 microM isoproterenol. Therefore, PP2A plays a key role in limiting PKA phosphorylation of phospholamban and TnI for myocyte contraction responses under beta(1)AR stimulation.
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Affiliation(s)
- Vania De Arcangelis
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA
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Ramchandra R, Hood SG, Watson AMD, May CN. Responses of cardiac sympathetic nerve activity to changes in circulating volume differ in normal and heart failure sheep. Am J Physiol Regul Integr Comp Physiol 2008; 295:R719-26. [PMID: 18635453 DOI: 10.1152/ajpregu.00824.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Factors controlling cardiac sympathetic nerve activity (CSNA) in the normal state and those causing the large increase in activity in heart failure (HF) remain unclear. We hypothesized from previous clinical findings that activation of cardiac mechanoreceptors by the increased blood volume in HF may stimulate sympathetic nerve activity (SNA), particularly to the heart via cardiocardiac reflexes. To investigate the effect of volume expansion and depletion on CSNA we have made multiunit recordings of CSNA in conscious normal sheep and sheep paced into HF. In HF sheep (n = 9) compared with normal sheep (n = 9), resting levels of CSNA were significantly higher (34 +/- 5 vs. 93 +/- 2 bursts/100 heart beats, P < 0.05), mean arterial pressure was lower (76 +/- 3 vs. 87 +/- 2 mmHg; P < 0.05), and central venous pressure (CVP) was greater (3.0 +/- 1.0 vs. 0.0 +/- 1.0 mmHg; P < 0.05). In normal sheep (n = 6), hemorrhage (400 ml over 30 min) was associated with a significant increase in CSNA (179 +/- 16%) with a decrease in CVP (2.7 +/- 0.7 mmHg). Volume expansion (400 ml Gelofusine over 30 min) significantly decreased CSNA (35 +/- 12%) and increased CVP (4.7 +/- 1.0 mmHg). In HF sheep (n = 6) the responses of CSNA to both volume expansion and hemorrhage were severely blunted with no significant changes in CSNA or heart rate with either stimulus. In summary, these studies in a large conscious mammal demonstrate that in the normal state directly recorded CSNA increased with volume depletion and decreased with volume loading. In contrast, both of these responses were severely blunted in HF with no significant changes in CSNA during either hemorrhage or volume expansion.
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Affiliation(s)
- Rohit Ramchandra
- Howard Florey Institute, Univ. of Melbourne, Parkville, Victoria, 3010, Australia
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Yamamoto R, Akazawa H, Ito K, Toko H, Sano M, Yasuda N, Qin Y, Kudo Y, Sugaya T, Chien KR, Komuro I. Angiotensin II Type 1a Receptor Signals are Involved in the Progression of Heart Failure in MLP-Deficient Mice. Circ J 2007; 71:1958-64. [DOI: 10.1253/circj.71.1958] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Rie Yamamoto
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Hiroshi Akazawa
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
- Division of Cardiovascular Pathophysiology, Chiba University Graduate School of Medicine
| | - Kaoru Ito
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Haruhiro Toko
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Masanori Sano
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Noritaka Yasuda
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Yingjie Qin
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | - Yoko Kudo
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
| | | | | | - Issei Komuro
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
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Yarbrough WM, Mukherjee R, Squires CE, Reese ES, Leiser JS, Stroud RE, Sample JA, Hendrick JW, Mingoia JT, McLean JE, Hardin AE, Dowdy KB, Spinale FG. Caspase inhibition attenuates contractile dysfunction following cardioplegic arrest and rewarming in the setting of left ventricular failure. J Cardiovasc Pharmacol 2005; 44:645-50. [PMID: 15550782 DOI: 10.1097/00005344-200412000-00004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperkalemic cardioplegic arrest (HCA) and rewarming evokes postoperative myocyte contractile dysfunction, a phenomenon of particular importance in settings of preexisting left ventricular (LV) failure. Caspases are intracellular proteolytic enzymes recently demonstrated to degrade myocardial contractile proteins. This study tested the hypothesis that myocyte contractile dysfunction induced by HCA could be ameliorated with caspase inhibition in the setting of compromised myocardial function. LV myocytes were isolated from control pigs (n = 9, 30 kg) or pigs with LV failure induced by rapid pacing (n = 6, 240 bpm for 21 days) and were randomized to the following: (1) normothermia (2003 myocytes), incubation in cell culture medium for 2 hours at 37 degrees C; (2) HCA only (506 myocytes), incubation for 2 hours in hypothermic HCA solution (4 degrees C, 24 mEq K); or (3) HCA + z-VAD, incubation in hypothermic HCA solution supplemented with 10 microM of the caspase inhibitor z-VAD (z-Val-Ala-Asp-fluoromethyl-ketone, 415 myocytes). Inotropic responsiveness was examined using beta-adrenergic stimulation (25 nM isoproterenol). Ambient normothermic myocyte shortening velocity (microm/s) was reduced with LV failure compared with control values (54 +/- 2 versus 75 +/- 2, respectively, P < 0.05). Following HCA, shortening velocity decreased in the LV failure and control groups (27 +/- 5 and 45 +/- 3, P < 0.05). Institution of z-VAD increased myocyte shortening velocity following HCA in both the LV failure and control groups (49 +/- 5 and 65 +/- 5, P < 0.05). Moreover, HCA supplementation with z-VAD increased beta-adrenergic responsiveness in both groups compared with HCA-only values. This study provides proof of concept that caspase activity contributes to myocyte contractile dysfunction following simulated HCA. Pharmacologic caspase inhibition may hold particular relevance in the execution of cardiac surgical procedures requiring HCA in the context of preexisting LV failure.
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Affiliation(s)
- William M Yarbrough
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Abstract
Through an integrative understanding of cardiovascular pathophysiologic characteristics at the multiorgan level, significant achievements in cardiovascular therapeutics have been achieved and enabled the rationale design and development of drugs such as the angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). In this article, we present a detailed review of the physiologic features of the renin-angiotensin-aldosterone system (RAAS), ACE inhibitors and ARB clinical pharmacologic characteristics, and specific diseases in which they are considered to be the standard of the care as supported by important clinical trial data. It is envisioned that an updated and detailed understanding of ACE inhibitors and ARBs will facilitate their successful use in the treatment of heart failure, myocardial infarction, hypertension, renal failure, and diabetic nephropathy.
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Affiliation(s)
- Joseph Wong
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Kim YK, Mankad S, Kim SJ, Takagi G, Tamura T, Gerdes AM, Bishop SP, Kramer CM. Adding angiotensin II type 1 receptor blockade to angiotensin-converting enzyme inhibition limits myocyte remodeling after myocardial infarction. J Card Fail 2003; 9:238-45. [PMID: 12815575 DOI: 10.1054/jcaf.2003.32] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Adding angiotensin II type 1 receptor blockade (ARB) to angiotensin-converting enzyme inhibition (ACEI) further attenuates left ventricular (LV) remodeling in an ovine model of myocardial infarction (MI). We hypothesized that combined therapy with ACEI and ARB (CT) would be additive in the limitation of the myocyte hypertrophy and dysfunction that occurs in untreated adjacent noninfarcted regions during remodeling. METHODS AND RESULTS Nineteen sheep underwent coronary ligation to create a moderate-sized anteroapical infarction. Post-MI day 2, sheep were randomized to therapy with ramipril (ACEI, n = 5) or ramipril plus losartan (CT, n = 6) or none (untreated, n = 8). Infarct size was similar between groups. At 8 weeks post-MI, myocytes were isolated from regions adjacent to and remote from the infarct to measure morphometric indices (cell volume, length, cross-sectional area, width) and parameters of contraction (% shortening and -dL/dt, rate of shortening) and relaxation (+dL/dt [rate of relengthening] and TR 70% [time for 70% relengthening]). Volume % collagen was measured from adjacent and remote regions. Adjacent myocyte volume was different between groups (2.5 +/- 0.1 x 10(4) microm(3) in CT, 3.0 +/- 0.4 x 10(4) microm(3) in ACEI, 3.5 +/- 0.2 x 10(4) microm(3) in untreated, analysis of variance [ANOVA] P =.001) as was length (158 +/- 4 microm, 161 +/- 9 microm, 189 +/- 8 microm, respectively, ANOVA P <.001). Adjacent cell volume and length in CT were lower than untreated (P <.05). Percent shortening and -dL/dt of isolated adjacent myocytes were improved with both ACEI (7.9 +/- 0.3%, -131 +/- 6 microm/sec, P <.05) and CT (7.7 +/- 0.3%, -144 +/- 8 microm/sec, P <.05) compared with no therapy (6.4 +/- 0.4%, -104 +/- 7 microm/sec), as was both +dL/dt and TR 70%. No between-group difference in volume % collagen was found in adjacent or remote regions. CONCLUSION Compared with ACEI alone, the addition of ARB further limits adjacent noninfarcted myocyte hypertrophy during post-MI LV remodeling. Both ACEI alone and CT preserve isolated unloaded myocyte function, but neither significantly reduce interstitial collagen. The additional benefit of ARB on regional and global function in vivo may also be due to other factors including regional load.
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Affiliation(s)
- Young-Kwon Kim
- Department of Cell Biology and Molecular Medicine, UMDNJ-New Jersey Medical School, New Jersey, USA
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Abstract
BACKGROUND Although current therapies have improved heart failure (HF) outcome, hospitalizations continue at high rates. The Valsartan Heart Failure Trial (Val-HeFT) showed that valsartan reduced the risk of first worsening HF hospitalization by 27.5% versus placebo (P <.001). This article analyzes all-cause and investigator-assessed HF hospitalization in Val-HeFT overall and in subgroups defined by preexisting HF therapy. METHODS Val-HeFT was a randomized, double-blind parallel-arm study in which HF patients (New York Heart Association class II-IV) received either valsartan (n = 2511, force-titrated to 160 mg twice daily) or placebo (n = 2499) in addition to prescribed HF therapy. Total and per patient-year investigator-assessed hospitalizations (all-cause or HF) were analyzed according to prescribed therapy at baseline (angiotensin-converting enzyme inhibitors [ACEI] and beta-blockers [BB]). RESULTS Hospitalization for worsening HF accounted for 35% of all hospitalizations. There were 2856 and 3106 total all-cause hospitalizations in the valsartan and placebo groups, respectively, an 8% reduction (P =.145). Valsartan significantly reduced the overall number of investigator-assessed HF hospitalizations (-22.4%, P =.002) and reduced HF hospitalizations in the combination therapy subgroups (significant for ACEI+/BB- P =.003 and ACEI-/BB- P =.028) except those receiving both ACEI and BB. The benefit of valsartan versus placebo was more pronounced in reducing the number of patients with recurrent HF hospitalization (-20.6%) than single hospitalizations (-8.7%). CONCLUSIONS Addition of valsartan to prescribed HF therapy demonstrated significant reductions in HF hospitalizations and was particularly beneficial in reducing recurrent HF hospitalization.
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Affiliation(s)
- Peter Carson
- Department of Veterans' Affairs, Medical Center, Washington, DC 20422, USA
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Shimoni Y. Inhibition of the formation or action of angiotensin II reverses attenuated K+ currents in type 1 and type 2 diabetes. J Physiol 2001; 537:83-92. [PMID: 11711563 PMCID: PMC2278945 DOI: 10.1111/j.1469-7793.2001.0083k.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
1. Transient and sustained calcium-independent outward K(+) currents (I(t) and I(SS)) as well as action potentials were recorded in cardiac ventricular myocytes isolated from two models of diabetes mellitus. 2. Rats injected (I.V.) with streptozotocin (STZ, 100 mg kg(-1)) 6-10 days before cell isolation developed insulin-dependent (type 1) diabetes. I(t) and I(SS) were attenuated and the action potential prolonged. Incubation of myocytes (6-9 h) with the angiotensin II (ATII) receptor blockers saralasin or valsartan (1 microM) significantly augmented these currents. Inclusion of valsartan (1 g l(-1)) in the drinking water for 5-10 days prior to and following STZ injection partially prevented current attenuation. 3. Incubation of myocytes from STZ-treated rats (6-9 h) with 1 microM quinapril, an angiotensin-converting enzyme (ACE) inhibitor, significantly augmented I(t) and I(SS) and shortened the ventricular action potential. I(t) augmentation was not due to changes in steady-state inactivation or in recovery from inactivation. No acute effects of quinapril were observed. 4. The effects of quinapril and valsartan were abolished by 2 microM cycloheximide. 5. Myocytes were isolated from the db/db mouse, a leptin receptor mutant that develops symptoms of non-insulin-dependent (type 2) diabetes. K+ currents in these cells were also attenuated, and the action potentials prolonged. Incubation of these cells (> 6 h) with valsartan (1 microM) significantly enhanced the transient and sustained outward currents. 6. These results confirm recent suggestions that cardiac myocytes contain a renin-angiotensin system, which is activated in diabetes. It is proposed that chronic release of ATII leads to changes in ionic currents and action potentials, which can be reversed by blocking the formation or action of ATII. This may underlie the proven benefits of ATII receptor blockade or ACE inhibition in diabetes, by providing protection against cardiac arrhythmias.
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Affiliation(s)
- Y Shimoni
- Department of Physiology and Biophysics, Cardiovascular Research Group, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
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Dohi K, Onishi K, Kitamura T, Okinaka T, Ito M, Isaka N, Nakano T. Functional role of endogenous endothelin-1 in congestive heart failure treated with angiotensin II receptor antagonist. THE JAPANESE JOURNAL OF PHYSIOLOGY 2001; 51:445-53. [PMID: 11564281 DOI: 10.2170/jjphysiol.51.445] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Interactions between angiotensin (ANG) II and endothelin (ET)-1 receptor transduction pathways have been unclear in congestive heart failure (CHF). Therefore the objects of this study are, in CHF, whether production of ET-1 is modulated by ANG II and/or whether hemodynamic effects of endogenous ET-1 are modulated by ANG II. Twelve dogs were randomly assigned to two groups: untreated (n = 6) and treated with ANG II type 1 (AT1) receptor antagonist (TCV116, 1.5 mg/kg/d) (n = 6). After rapid ventricular pacing (240 bpm) for 4 weeks, plasma and cardiac ET-1 levels were compared between the two groups. Acute hemodynamic effects of a nonspecific ET(A&B) receptor antagonist, TAK044 (3 mg/kg plus 3 mg/kg/h i.v.) were examined in both groups by a conductance catheter and a micromanometer. After 4 weeks of pacing, plasma and cardiac tissue ET-1 levels were elevated in both groups to a similar degree. In the group treated with TCV116, TAK044 produced an increase in stroke volume and a decrease in total systemic resistance; heart rate was unchanged. The time constant of left ventricular (LV) relaxation was significantly decreased. The slope of LV end-systolic pressure-volume relation (E(ES)) was increased (p < 0.05), indicating an increased LV contractility. Thus endogenous ET-1 produces an arterial vasoconstriction and impairs LV contractility and relaxation in CHF with AT1 receptor antagonism. These hemodynamic responses to TAK044 in CHF treated with TCV116 were similar in untreated CHF. These results suggest that the production of ET-1 and the cardiac effects of endogenous ET-1 in CHF may be unaffected by ANG II acting through AT1 receptors.
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Affiliation(s)
- K Dohi
- The First Department of Internal Medicine, Mie University School of Medicine, Tsu, 514-8507, Japan
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McElmurray JH, Mukherjee R, Patterson TM, Goldberg A, King MK, Hendrick JW, Gay DM, Clair MJ, Jolly JR, Spinale FG. Comparison of amlodipine or nifedipine treatment with developing congestive heart failure: effects on myocyte contractility. J Card Fail 2001; 7:158-64. [PMID: 11420768 DOI: 10.1054/jcaf.2001.24374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Past studies have suggested that amlodipine, a dihydropyridine L-type Ca(2+) channel antagonist, may exert useful effects in congestive heart failure (CHF). The present study examined the effects of amlodipine or nifedipine treatment in a model of developing CHF on left ventricular (LV) pump function and myocyte contractility. METHODS AND RESULTS Pigs (25 kg) were randomly assigned to 1 of 4 groups: 1) pacing-induced CHF (rapid atrial pacing at 240 bpm) for 3 weeks (n = 9), 2) concomitant Ca(2+) channel blockade with amlodipine (1.5 mg/kg/day) and rapid pacing (n = 7), 3) concomitant Ca(2+) channel blockade with nifedipine (0.7 mg/kg twice daily) and rapid pacing (n = 7), and 4) sham controls (n = 7). LV fractional shortening fell with pacing CHF from baseline values (17% +/- 1% v 42% +/- 1%, P <.05). With rapid pacing and concomitant amlodipine treatment, LV fractional shortening increased from pacing CHF values (24% +/- 1%, P <.05) but was unchanged with concomitant nifedipine treatment (20% +/- 2%, P =.2). LV myocyte velocity of shortening, as measured by high speed videomicroscopy, was reduced with pacing CHF compared with controls (42 +/- 2 microm/s v 87 +/- 9 microm/s, P <.05), and increased from pacing CHF values with amlodipine or nifedipine treatment (62 +/- 8 microm/s, 64 +/- 4 microm/s, respectively; P <.05). Inotropic response to extracellular Ca(2+) (8 mmol/L) was reduced with pacing CHF (94 +/- 5 microm/s v 160 +/- 15 microm/s, P <.05) and increased from CHF values with amlodipine or nifedipine treatment (132 +/- 14 microm/s and 133 +/- 7 microm/s, respectively, P <.05) CONCLUSIONS: These results suggest that the primary mechanism for the effects of amlodipine on myocyte contractility in developing CHF is because of direct Ca(2+) channel blockade.
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Affiliation(s)
- J H McElmurray
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Carson P, Giles T, Higginbotham M, Hollenberg N, Kannel W, Siragy HM. Angiotensin receptor blockers: evidence for preserving target organs. Clin Cardiol 2001; 24:183-90. [PMID: 11288962 PMCID: PMC6654811 DOI: 10.1002/clc.4960240303] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/1999] [Accepted: 01/27/2000] [Indexed: 01/07/2023] Open
Abstract
Hypertension is a major problem throughout the developed world. Although current antihypertensive treatment regimens reduce morbidity and mortality, patients are often noncompliant, and medications may not completely normalize blood pressure. As a result, current therapy frequently does not prevent or reverse the cardiovascular remodeling that often occurs when blood pressure is chronically elevated. Blockade of the renin-angiotensin system (RAS) is effective in controlling hypertension and treating congestive heart failure. Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) inhibit the activity of the RAS, but these two classes of antihypertensive medications have different mechanisms of action and different pharmacologic profiles. Angiotensin-converting enzyme inhibitors block a single pathway in the production of angiotensin II (Ang II). In addition, angiotensin I is not the only substrate for ACE. The ACE inhibitors also block the degradation of bradykinin that may have potential benefits in cardiovascular disease. Bradykinin is, however, the presumed cause of cough associated with ACE inhibitor therapy. Data from clinical trials on ACE inhibitors serve to support the involvement of the RAS in the development of cardiovascular disease. Angiotensin receptor blockers act distally in the RAS to block the Ang II type 1 (AT1) receptor selectively. Thus, ARBs are more specific agents and avoid many side effects. Experimental and clinical trials have documented the efficacy of ARBs in preserving target-organ function and reversing cardiovascular remodeling. In some instances, maximal benefit may be obtained with Ang II blockade using both ARBs and ACE inhibitors. This review describes clinical trials that document the efficacy of ARBs in protecting the myocardium, blood vessels, and renal vasculature.
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Affiliation(s)
- P Carson
- Department of Cardiology, Veterans Affairs Medical Center, Washington, DC, USA
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16
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Suzuki J, Ohta H, Hanada K, Kawai N, Ikeda T, Nakao M, Ikemoto F, Nishikibe M. Acute effects of E-3174, a human active metabolite of losartan, on the cardiovascular system in tachycardia-induced canine heart failure. Hypertens Res 2001; 24:65-74. [PMID: 11213032 DOI: 10.1291/hypres.24.65] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The aim of this study was to evaluate the acute effects of E-3174, a human active metabolite of the AT1 receptor antagonist, losartan, on hemodynamic functions in dogs with severe heart failure (HF). In dogs, insignificant plasma levels of E-3174 are present following administration of losartan, and therefore, the effects of these two drugs can be studied independently in the dog. HF was established by rapid pacing of the right ventricle (250-270 beats/min) for 4 weeks. We examined changes in cardiovascular functions after acute intravenous administration of losartan (1 mg/kg) and E-3174 (0.3 and 1 mg/kg), as well as an ACE inhibitor, enalapril (0.3 and 1 mg/kg), under condition of HF. The HF before treatment was characterized by increases in pre- and after-load of the left ventricle (LV), consequent low cardiac output, and LV dilatation. E-3174 at 0.3 and 1 mg/kg reduced pulmonary artery pressure (-13+/-6% and -22+/-3% from baseline, respectively, p<0.05), pulmonary capillary wedge pressure (-18+/-4% and -36+/-10%, p<0.05) and mean arterial pressure (-24+/-2% and -36+/-7%, p<0.05), increased stroke volume (SV: +12+/-7% p>0.05; +36 +/-19%, p<0.05), and reduced peripheral resistance (-23+/-5% and -41+/-9%, p<0.05), but had no effect on the first derivative of left ventricular pressure (dP/dt/P) or the time constant for relaxation. Effects of losartan at 1 mg/kg were similar to those of 0.3 mg/kg of E-3174. Enalapril at 1 mg/kg caused changes comparable to those seen after E-3174 administration (1 mg/kg), except that the increase in SV (+16+/-8%, p<0.05) with enalapril was not as great as that with E-3174. Both losartan at 1 mg/kg and E-3174 at 0.3 and 1 mg/kg increased fractional shortening to a similar extent (FS: +52+/-12%, +47+/-8% and +56+/-8%), while enalapril at 0.3 and 1 mg/kg had no significant effects on FS. Reflex elevation of plasma renin activity induced by 1 mg/kg of E-3174 was similar to that caused by 1 mg/kg of enalapril, suggesting that the two drugs achieved similar inhibition of the endogenous renin angiotensin system. Our study demonstrated that acute blockade of the AT1 receptor with E-3174 reduced elevated pre- and after-load and consequently increased stroke volume in a canine HF model. With the exception of changes in stroke volume, these effects of E-3174 were comparable to those produced by enalapril, and were 3 times stronger than those by losartan.
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Affiliation(s)
- J Suzuki
- Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical, Co., Ltd., Japan
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17
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Kawai H, Stevens SY, Liang CS. Renin-angiotensin system inhibition on noradrenergic nerve terminal function in pacing-induced heart failure. Am J Physiol Heart Circ Physiol 2000; 279:H3012-9. [PMID: 11087259 DOI: 10.1152/ajpheart.2000.279.6.h3012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic angiotensin-converting enzyme (ACE) inhibition has been shown to improve cardiac sympathetic nerve terminal function in heart failure. To determine whether similar effects could be produced by angiotensin II AT(1) receptor blockade, we administered the ACE inhibitor quinapril, angiotensin II AT(1) receptor blocker losartan, or both agents together, to rabbits with pacing-induced heart failure. Chronic rapid pacing produced left ventricular dilation and decline of fractional shortening, increased plasma norepinephrine (NE), and caused reductions of myocardial NE uptake activity, NE histofluorescence profile, and tyrosine hydroxylase immunostained profile. Administration of quinapril or losartan retarded the progression of left ventricular dysfunction and attenuated cardiac sympathetic nerve terminal abnormalities in heart failure. Quinapril and losartan together produced greater effects than either agent alone. The effect of renin-angiotensin system inhibition on improvement of left ventricular function and remodeling, however, was not sustained. Our results suggest that the effects of ACE inhibitors are mediated via the reduction of angiotensin II and that angiotensin II plays a pivotal role in modulating cardiac sympathetic nerve terminal function during development of heart failure. The combined effect of ACE inhibition and angiotensin II AT(1) receptor blockade on cardiac sympathetic nerve terminal dysfunction may contribute to the beneficial effects on cardiac function in heart failure.
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Affiliation(s)
- H Kawai
- Cardiology Unit, Department of Medicine, and Department of Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, New York 14642, USA
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18
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Krombach RS, McElmuray JH, Gay DM, Clair MJ, Mukherjee R, Goldberg AT, Baicu SC, Spinale FG. Bradykinin degradation and relation to myocyte contractility. J Cardiovasc Pharmacol Ther 2000; 5:291-9. [PMID: 11150399 DOI: 10.1054/jcpt.2000.16694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Past studies have demonstrated that exogenous bradykinin (BK) causes vasodilation and increases coronary blood flow, effects that may be beneficial in the setting of cardiac disease states. An important pathway for BK degradation is through angiotensin-converting enzyme (ACE), which results in the formation of a degradative peptide, BK((1-7)). The goal of this study was to examine the effects of BK, BK((1-7)), and the potential modulation of BK by ACE inhibition on myocyte contractility. METHODS AND RESULTS Contractile function was examined in isolated adult porcine (n = 15) left ventricular (LV) myocyte preparations in the presence or absence of BK (10(-8) mol/L), BK((1-7)) (10(-8) mol/L), and with pretreatment by ACE inhibition (benazaprilat). Myocyte velocity of shortening fell by over 15% in the presence of BK and by 8% with BK((1-7)) (P <.05 vs basal). ACE inhibition blunted the negative effect of BK on myocyte velocity of shortening by over 60% (P <.05). Furthermore, robust ACE activity coupled with significant BK degradation was demonstrated in LV-isolated myocyte preparations, and BK proteolysis was influenced by ACE inhibition. CONCLUSION These results suggest that BK has a direct effect on LV myocyte contractility, and that this effect may be mediated by proteolysis of BK at the level of the LV myocyte sarcolemma.
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Affiliation(s)
- R S Krombach
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC 29425, USA
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19
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Carson PE. Rationale for the use of combination angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker therapy in heart failure. Am Heart J 2000; 140:361-6. [PMID: 10966531 DOI: 10.1067/mhj.2000.109215] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Heart failure (HF) is a major cause of morbidity and mortality in the United States. The renin-angiotensin system (RAS) plays a major role in its pathophysiology, and angiotensin-converting enzyme (ACE) inhibitors are the cornerstone of therapy. However, HF continues to progress despite this therapy, perhaps because of production of angiotensin II by alternative pathways, which lead to direct stimulation of the angiotensin II receptor. Angiotensin II receptor blocker (ARB) therapy alone or in combination with the ACE inhibitor is a promising approach to block the RAS and slow HF progression more completely. METHODS The current medical literature on the pathophysiology of HF and the use of ACE inhibitors and ARBs was extensively reviewed. RESULTS Evidence from basic science, experimental animals, and clinical trials provides data on the safety and efficacy of RAS inhibition with ACE inhibitors and ARBs as monotherapy and in combination. Data from the Evaluation of Losartan in the Elderly (ELITE) II trial indicate that ARBs alone do not appear to be more effective than ACE inhibitors in HF, but studies evaluating their use in combination are currently ongoing. CONCLUSIONS The addition of an ARB offers more complete angiotensin II receptor blockade of the RAS than can be obtained by ACE inhibitors alone. Combination therapy preserves the benefits of bradykinin potentiation offered by ACE inhibitors while providing potential antitrophic influences of AT(2) receptor stimulation and may play an increased role in the treatment of chronic HF in the future.
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Affiliation(s)
- P E Carson
- Department of Cardiology, Veterans Administration Medical Center, Washington, DC 20422-0001, USA
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20
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Weinberg MS, Weinberg AJ, Zappe DH. Effectively targetting the renin-angiotensin-aldosterone system in cardiovascular and renal disease: rationale for using angiotensin II receptor blockers in combination with angiotensin-converting enzyme inhibitors. J Renin Angiotensin Aldosterone Syst 2000; 1:217-33. [PMID: 11881029 DOI: 10.3317/jraas.2000.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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21
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Azizi M, Linhart A, Alexander J, Goldberg A, Menten J, Sweet C, Ménard J. Pilot study of combined blockade of the renin-angiotensin system in essential hypertensive patients. J Hypertens 2000; 18:1139-47. [PMID: 10954007 DOI: 10.1097/00004872-200018080-00020] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Additive hemodynamic effects of combined blockade of the renin-angiotensin system by an angiotensin I converting enzyme inhibitor and an angiotensin II antagonist have been observed in sodium-depleted normotensive volunteers and in patients with congestive heart failure. OBJECTIVE To investigate whether the same additive hemodynamic effects occur in patients with hypertension and to verify the safety of such an approach. DESIGN Multicenter, randomized, double-blind, parallel-group, pilot study. PATIENTS 177 patients with mild-to-moderate hypertension [diastolic blood pressure (DBP): 95-115 mmHg after a 4-week placebo run-in period] were included in the study. INTERVENTION Combination therapy consisting of 50 mg losartan daily and 10 mg enalapril daily was administered for 6 weeks. The effects of this therapeutic regimen was compared with similar groups of patients who received either 50 mg losartan daily or 10 mg enalapril daily. MAIN OUTCOME MEASURES 24-hour ambulatory mean DBP and clinic DBP measured at trough after 6 weeks of treatment. RESULTS 24-hour ambulatory mean DBP did not significantly differ between treatment groups although the combination tended to lower BP more. The combination therapy was more effective on clinic DBP measured at trough than was losartan by 3.2 mmHg [confidence interval (95%, CI) 0.7-5.7 mmHg, P = 0.012], and more effective than enalapril by 4.0 mmHg (95% CI, 1.5-6.4 mmHg, P = 0.002). In a subgroup of 28 patients, higher plasma active renin and angiotensin I levels during blockade by the combination therapy were observed. This finding confirmed that the combination of the two agents inhibited the renin-angiotensin system to a greater extent than did either agent alone. CONCLUSION A combination of 10 mg enalapril daily and 50 mg losartan daily safely induces a supplementary, although modest, fall in clinic DBP in patients with mild-to-moderate essential hypertension.
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Affiliation(s)
- M Azizi
- Centre d'Investigations Cliniques 9201, Hôpital Broussais, Assistance Publique des Hôpitaux de Paris et INSERM, France.
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22
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Patten RD, Konstam MA. Ventricular remodeling and the renin angiotensin aldosterone system. CONGESTIVE HEART FAILURE (GREENWICH, CONN.) 2000; 6:187-192. [PMID: 12147951 DOI: 10.1111/j.1527-5299.2000.80159.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ventricular remodeling in patients with left ventricular systolic dysfunction is an indolent process that is associated with a poor prognosis. Clinical and experimental data support the central role played by the renin-angiotensin-aldosterone system in the pathophysiology of remodeling. ACE inhibitors improve the natural history of ventricular remodeling and the syndrome of heart failure. Experimental and preliminary clinical data suggest that angiotensin II type I receptor blockade also impacts favorably on remodeling. Some experimental studies suggest a possible synergistic effect when combining ACE inhibitors and angiotensin II type I receptor antagonists. Aldosterone, the regulation of which, in part, is independent of angiotensin II, is a direct mediator of the interstitial component of remodeling, and its blockade has been found to improve clinical outcomes. Future research will more precisely define the mechanism for ventricular remodeling and will yield more effective means of achieving a clinically relevant impact on this process. (c)2000 by CHF, Inc.
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Affiliation(s)
- R D Patten
- Division of Cardiology, Department of Medicine, New England Medical Center, Boston, MA 02111
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23
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Pfeffer MA. Enhancing cardiac protection after myocardial infarction: rationale for newer clinical trials of angiotensin receptor blockers. Am Heart J 2000; 139:S23-8. [PMID: 10618584 DOI: 10.1067/mhj.2000.102904] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Treatment of acute myocardial infarction (MI) has been advanced considerably in the past 20 years with the advent of acute reperfusion strategies such as thrombolytic therapy or primary angioplasty and the use of adjunctive medical therapies such as aspirin, beta-blockers, and HMG-CoA reductase inhibitors (statins); each has been proven to reduce morbidity and mortality rates after MI. Angiotensin-converting enzyme (ACE) inhibitors have earned an important place in this list of winners, particularly in patients clinically assessed as being at higher risk for cardiovascular death. The benefits of treating such patients with an ACE inhibitor have clearly shown significant improvements in survival that are both complementary and additive to the other proven therapies. However, a significant subset of patients treated with ACE inhibitors will die or have worsening congestive heart failure despite adequate therapy. Appropriate risk stratification can help guide the clinician in identifying patients at greatest risk for cardiovascular events after MI. Fortunately, investigators are currently exploring the potential benefits of more specific and selective blockade of the renin-angiotensin system with AT(1) receptor blockers (ARBs) in the hope of enhancing survival beyond that evidenced with ACE inhibition alone. These agents pharmacologically inhibit the renin-angiotensin system at the angiotensin (Ang) II type 1 receptor level. Although there are theories postulating why blocking the harmful effects of Ang II at this receptor would be more effective than inhibiting ACE-mediated conversion from inactive Ang I to Ang II, extrapolation to the clinical setting remains highly speculative. These hypotheses can only be tested by direct comparisons of ACE inhibitors and ARBs in the appropriate patient populations. The VALIANT (Valsartan in Acute Myocardial Infarction) trial is testing the hypothesis that interruption of the renin-angiotensin pathway by using the ARB valsartan alone or in combination with an ACE inhibitor will be more effective in saving lives than an ACE inhibitor alone in treating patients at high risk. This trial will enroll patients with symptoms of congestive heart failure or depressed left ventricular ejection fraction and randomly assign them to either captopril, valsartan, or the combination. Other proven conventional post-MI therapies are encouraged. This study will definitively determine whether the use of valsartan offers additional benefits over those achieved with ACE inhibitor monotherapy in patients at high risk after MI.
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Affiliation(s)
- M A Pfeffer
- Cardiovascular Division, Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA
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24
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Shimoni Y. Hormonal control of cardiac ion channels and transporters. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1999; 72:67-108. [PMID: 10446502 DOI: 10.1016/s0079-6107(99)00005-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Y Shimoni
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Alta., Canada.
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25
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Tanimura M, Sharov VG, Shimoyama H, Mishima T, Levine TB, Goldstein S, Sabbah HN. Effects of AT1-receptor blockade on progression of left ventricular dysfunction in dogs with heart failure. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H1385-92. [PMID: 10199866 DOI: 10.1152/ajpheart.1999.276.4.h1385] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of the present study was to determine the effects of early long-term monotherapy with the angiotensin II AT1-receptor antagonist valsartan on the progression of left ventricular (LV) dysfunction and remodeling in dogs with moderate heart failure (HF). Studies were performed in 30 dogs with moderate HF produced by multiple sequential intracoronary microembolizations. Embolizations were discontinued when LV ejection fraction was 30-40%. Two weeks after the last embolization, dogs were randomized to 3 mo of oral therapy with low-dose valsartan (400 mg twice daily, n = 10), to high-dose valsartan (800 mg twice daily, n = 10), or to no treatment at all (control, n = 10). Treatment with valsartan significantly reduced mean aortic pressure and LV end-diastolic pressure compared with control. In untreated dogs, LV ejection fraction decreased (37 +/- 1 vs. 29 +/- 1%, P = 0.001) and end-systolic volume (ESV) and end-diastolic volume (EDV) increased (81 +/- 5 vs. 92 +/- 5 ml, P < 0.001; 51 +/- 3 vs. 65 +/- 3 ml, P = 0.001, respectively) after 3 mo of follow-up compared with those levels before follow-up. In dogs treated for 3 mo with low-dose valsartan, ejection fraction was preserved (37 +/- 1 vs. 38 +/- 2%, pretreatment vs. posttreatment) as was ESV but not EDV. In dogs treated for 3 mo with high-dose valsartan, ejection fraction decreased (35 +/- 1 vs. 31 +/- 2%, P = 0.02) and ESV and EDV increased in a manner comparable to those levels in controls. Valsartan had no significant effects on cardiomyocyte hypertrophy or on the extent of interstitial fibrosis. We conclude that, for dogs with moderate HF, early long-term therapy with the AT1-receptor blocker valsartan decreases preload and afterload but has only limited benefits in attenuating the progression of LV dysfunction and chamber remodeling.
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MESH Headings
- Angiotensin Receptor Antagonists
- Animals
- Cardiac Output, Low/drug therapy
- Cardiac Output, Low/pathology
- Cardiac Output, Low/physiopathology
- Disease Progression
- Dogs
- Dose-Response Relationship, Drug
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Tetrazoles/therapeutic use
- Valine/analogs & derivatives
- Valine/therapeutic use
- Valsartan
- Ventricular Dysfunction, Left/drug therapy
- Ventricular Dysfunction, Left/pathology
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Remodeling/drug effects
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Affiliation(s)
- M Tanimura
- Division of Cardiovascular Medicine, Henry Ford Heart and Vascular Institute, Detroit 48202, Michigan, USA
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Spinale FG, Iannini JP, Mukherjee R, Melton DM, de Gasparo M. Angiotensin AT1 receptor inhibition, angiotensin-converting enzyme inhibition, and combination therapy with developing heart failure: cellular mechanisms of action. J Card Fail 1998; 4:325-32. [PMID: 9924854 DOI: 10.1016/s1071-9164(98)90238-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Past studies have shown that angiotensin-converting enzyme inhibition (ACEI) alone, angiotensin AT1 receptor blockade (AT1 block) alone, and combined treatment have differential effects on left ventricular (LV) function and geometry with developing congestive heart failure (CHF). The purpose of this study was to more carefully examine the cellular basis for these differential effects by using a model of pacing CHF. METHODS AND RESULTS Pigs were randomly assigned to five groups: (1) rapid pacing (240 bpm) for 3 weeks (n = 9), (2) concomitant ACEI (benazeprilat, 0.187 mg/kg/day) and pacing (n = 9), (3) concomitant AT1 block (valsartan, 3 mg/kg/day) and pacing (n = 9), (4) concomitant ACEI and AT1 receptor blockade (benazeprilat/valsartan, 0.05/3 mg/kg/day, respectively) and pacing (n = 9), and (5) sham controls (n = 10). The dosage protocol was based on obtaining a 50% reduction in angiotensin I and angiotensin II pressor response with no significant effects on mean basal arterial pressure. In the pacing group, LV fractional shortening (LVFS) fell compared with control group (13.4+/-1.4 v 39.1+/-1.0%, P < .05). With AT1 block, LVFS was unchanged from pacing only. ACEI and combined treatment increased LVFS from pacing values (25.2+/-0.9 v 20.9+/-1.9%, respectively, P < .05). LV myocyte shortening velocity was reduced with chronic pacing compared with control group (27.2+/-0.6 v 58.6+/-1.2 microm/s, P < .05) and remained reduced with AT1 block (28.0+/-0.5 microm/s, P < .05). Myocyte shortening velocity increased with ACEI or combination treatment (36.9+/-0.7 v 42.3+/-0.8 microm/s, respectively, P < .05). Concomitant treatment with either ACEI or AT1 blockade normalized myocyte action potential duration. In the combined ACEI and AT1 blockade group, all parameters of the myocyte action potential were unchanged from control values. CONCLUSIONS This study showed that combined ACEI and AT1 receptor blockade produced beneficial effects on myocyte contractility and electrophysiology when compared with either monotherapy alone and therefore may provide unique benefits with CHF.
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Affiliation(s)
- F G Spinale
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston 29425, USA
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27
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de Gasparo M, Levens N. Does blockade of angiotensin II receptors offer clinical benefits over inhibition of angiotensin-converting enzyme? PHARMACOLOGY & TOXICOLOGY 1998; 82:257-71. [PMID: 9677617 DOI: 10.1111/j.1600-0773.1998.tb01572.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Angiotensin AT1 receptor antagonists represent a new class of drugs for the treatment of hypertension. They are specific for the renin-angiotensin system, selective for the angiotensin AT1 receptor, and act independently of the angiotensin II synthetic pathway. Blockade of the renin-angiotensin system at the receptor level should therefore be more complete. The high circulating levels of angiotensin II following angiotensin AT1 receptor blockade could be beneficial in stimulating other unblocked angiotensin receptors, especially the AT2 receptor. It has been proposed that the angiotensin AT2 receptor, which is re-expressed or up-regulated during pathological circumstances, counterbalances the effect of the stimulation of the angiotensin AT1 receptor. Through this mechanism, angiotensin AT1 antagonists may be superior to ACE inhibitors in cardiac and vascular remodelling as well as in kidney insufficiency. Long-term trials are required to demonstrate the possible clinical superiority of this new class of antihypertensive agents.
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