1
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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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2
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Zhang N, Chen T, Liu C, Tang B, Nie L, An H, Zhao D, Pan L, Yu M. Inhibition of ubiquitin protein expression and 20S proteasome activity by irbesartan prevents post-infarction ventricular remodeling and decreases TNF-α generation. Biomed Rep 2013; 1:935-939. [PMID: 24649056 DOI: 10.3892/br.2013.165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/30/2013] [Indexed: 01/12/2023] Open
Abstract
Myocardial infarction (MI) may induce severe alterations of the cardiac contractile function that may, in turn, lead to heart failure (HF). The ubiquitin-proteasome system (UPS) plays a critical role in cardiac remodeling following MI. Angiotensin II type 1 receptor (AT1R) blockers effectively prevent left ventricular (LV) remodeling. However, it has not been elucidated whether the preventive effect of AT1R-blockers on LV remodeling is mediated through the UPS pathway. In the present study, with the use of cardiac morphometric parameters, haemodynamic measurements and enzyme-linked immunosorbent assay, we demonstrated that post-ischemic HF rats exhibited a significant increase in ventricular remodeling and irbesartan was effective in reversing cardiac remodeling. The expression of TNF-α, ubiquitin protein and 20S proteasome were significantly increased in the MI control group and irbesartan was shown to dose-dependently inhibit the expression of TNF-α, ubiquitin protein and 20S proteasome. In conclusion, it was hypothesized that UPS signaling is involved in ventricular remodeling following MI and the mechanism underlying the effect of irbesartan on ventricular remodeling may be associated with the downregulation of the expression of TNF-α, ubiquitin protein and 20S proteasome.
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Affiliation(s)
- Naiju Zhang
- Department of Pharmacy, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
| | - Tianping Chen
- Department of Cardiovasology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
| | - Chunfang Liu
- Department of Cardiovasology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
| | - Bi Tang
- Department of Cardiovasology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
| | - Ling Nie
- Department of Pharmacy, Bengbu Second People's Hospital, Bengbu, Anhui 233000, P.R. China
| | - Huiling An
- Department of Pharmacy, Bengbu Second People's Hospital, Bengbu, Anhui 233000, P.R. China
| | - Duilan Zhao
- Department of Pharmacy, Bengbu Second People's Hospital, Bengbu, Anhui 233000, P.R. China
| | - Li Pan
- Department of Pharmacy, Bengbu Second People's Hospital, Bengbu, Anhui 233000, P.R. China
| | - Meiling Yu
- Department of Pharmacy, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
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Berthonneche C, Sulpice T, Tanguy S, O'Connor S, Herbert JM, Janiak P, de Leiris J, Boucher F. AT1 Receptor Blockade Prevents Cardiac Dysfunction after Myocardial Infarction in Rats. Cardiovasc Drugs Ther 2005; 19:251-9. [PMID: 16193242 DOI: 10.1007/s10557-005-3695-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Myocardial infarction (MI) can induce severe alterations of contractile function that can, in turn, lead to heart failure. In a previous study, we have demonstrated that TNF-alpha was involved in cardiac contractile dysfunction 7 days after coronary artery ligation in rats. Since Angiotensin II type 1 (AT1) receptor can be involved in TNF-alpha production, we have investigated whether early short-term treatment with irbesartan, an AT1 receptor blocker, is able to limit TNF-alpha production within the heart and to improve cardiac function and geometry following MI in rats. Male Wistar rats were subjected to permanent coronary artery ligation and received either a placebo or irbesartan (50 mg/kg/day) per os daily from day 3 to day 6 after surgery. On day 7, cardiac TNF-alpha was significantly reduced in MI rats receiving irbesartan (p < 0.05). Moreover, irbesartan improved residual LV end-diastolic pressure under both basal conditions and after volume overload (p < 0.01). In addition, a significant leftward shift of the pressure-volume curve in the irbesartan-treated group was found versus placebo. Finally, infarct expansion index was also significantly improved by irbesartan (p < 0.01). In conclusion, early, short-term AT1 receptor blockade limits post-infarct cardiac TNF-alpha production and diminishes myocardial alterations observed 7 days after MI in the rat.
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Affiliation(s)
- Corinne Berthonneche
- Laboratoire NVMC, IFRT 130 Ingénierie pour le Vivant, Université Joseph Fourier, Grenoble, France
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Lacour C, Roccon A, Galindo G, Canals F, Hogie M, Segondy D, Briand D, Roque C, Herbert JM, Nisato D. Effects of differential blockade of the renin-angiotensin system in postinfarcted rats. Fundam Clin Pharmacol 2004; 18:299-307. [PMID: 15147281 DOI: 10.1111/j.1472-8206.2004.00235.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study compared short-term effects of the AT(1)-receptor antagonist, irbesartan with the angiotensin-converting enzyme (ACE) inhibitor, enalapril on systemic haemodynamics and cardiac remodelling in post-myocardia-infarcted (MI) rats. MI Sprague-Dawley rats were orally treated for 4 weeks with irbesartan (50 mg/kg/day) or enalapril (10 mg/kg/day). Then, cardiac and systemic haemodynamics were measured. Compared with the sham-operated group, left ventricular end-diastolic pressure (LVEDP), diastolic pressure (LVDP), heart weight to body weight ratio were all significantly increased in the MI group while the LV contractility (dP/dt) and pulsatile arterial pressure were significantly reduced. Both drugs reduced the elevated LVEDP and LVDP and prevented cardiac hypertrophy. Furthermore, irbesartan attenuated the right shift of the pressure-volume curves, prevented postinfarction-induced increase in urinary cyclic guanosine monophosphate and reduced urinary aldosterone excretion. Although both drugs were able to prevent further cardiac hypertrophy and improved cardiac filling pressure, only irbesartan limited LV dilatation. These data indicate that blockade of the renin-angiotensin system at the level of AT1 receptors may have a better cardioprotective benefit than reducing angiotensin II levels by ACE inhibition.
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Affiliation(s)
- Colette Lacour
- Cardiovascular Thrombosis Department, Sanofi-Synthélabo Recherche, 34184 Montpellier 04, France
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5
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Schäfer A, Fraccarollo D, Tas P, Schmidt I, Ertl G, Bauersachs J. Endothelial dysfunction in congestive heart failure: ACE inhibition vs. angiotensin II antagonism. Eur J Heart Fail 2004; 6:151-9. [PMID: 14984722 DOI: 10.1016/j.ejheart.2003.10.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2003] [Revised: 08/17/2003] [Accepted: 10/23/2003] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Endothelial dysfunction of the vasculature contributes to the elevated peripheral resistance and reduced myocardial perfusion in congestive heart failure (CHF). The present study systematically investigated the effect of angiotensin II (AT(1))- receptor blockade on vascular superoxide (O(2)(-)) production and endothelial dysfunction. METHODS AND RESULTS Vasodilator responses and O(2)(-) production were determined in aortic rings from Wistar rats with experimental CHF 10 weeks after extensive myocardial infarction and compared with sham-operated animals (Sham). Rats were either treated with placebo (P), with the AT(1)-receptor antagonist Irbesartan (50 mg kg(-1) day(-1)) or with the ACE inhibitor Trandolapril (0.3 mg kg(-1) day(-1)). In CHF-P, endothelium-dependent, acetylcholine-induced relaxation was significantly attenuated compared with Sham-P. Chronic treatment with Trandolapril or Irbesartan significantly improved endothelium-dependent relaxation. Aortic O(2)(-) formation was markedly increased in CHF, and was not significantly affected by Trandolapril treatment, while it was reduced by Irbesartan. eNOS expression was reduced in CHF and normalised by both treatments. CONCLUSION Endothelial vasomotor function in CHF rats was normalised by long-term treatment with an ACE inhibitor or an AT(1)-antagonist. Reduced aortic eNOS expression was normalised by both treatments, whereas aortic superoxide formation was only reduced by the AT(1)-antagonist Irbesartan.
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Affiliation(s)
- Andreas Schäfer
- Medizinische Klinik der Julius-Maximilians-Universität Würzburg, Josef Schneider Str. 2, D-97080 Würzburg, Germany
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Sethi R, Shao Q, Takeda N, Dhalla NS. Attenuation of changes in G(i)-proteins and adenylyl cyclase in heart failure by an ACE inhibitor, imidapril. J Cell Mol Med 2004; 7:277-86. [PMID: 14594552 PMCID: PMC6741641 DOI: 10.1111/j.1582-4934.2003.tb00228.x] [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: 11/28/2022] Open
Abstract
Cardiac dysfunction in animals with congestive heart failure due to myocardial infarction (MI) is known to be associated with a wide variety of defects in receptor and post-receptor mechanisms. Since the heart function have been shown to be improved by treatment with different angiotensin converting enzyme (ACE) inhibitors, we examined the effects of imidapril, an ACE inhibitor, on changes in post-receptor mechanisms involving adenylyl cyclase (AC) and G proteins in the failing heart. Heart failure in rats was induced by occluding the coronary artery and 3 weeks later the animals were treated daily with 1 mg/kg (orally) imidapril for 5 weeks. The animals were assessed for their left ventricular function and crude membranes were isolated from the viable left ventricle and examined for AC activities as well as G-protein activities and expression. Animals with heart failure exhibited depressions in ventricular function and AC activities in the absence or presence of forskolin, NaF and Gpp(NH)p. The AC activity in the presence of pertussis toxin was increased whereas that in the presence of cholera toxin was decreased in the failing heart. Protein contents and mRNA levels for G(i)-proteins were increased whereas those for G(s)-proteins were unaltered in the infarcted heart. All these changes due to MI were prevented by imidapril treatment. The results indicate that the depressed cardiac function in the failing heart may partly be due to the direct effects of changes in AC and G(i) proteins.
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Affiliation(s)
- R Sethi
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre & Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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Martínez LA, Villalobos-Molina R. Early and chronic captopril or Losartan therapy reduces infarct size and avoids congestive heart failure after myocardial infarction in rats. Arch Med Res 2003; 34:357-61. [PMID: 14602500 DOI: 10.1016/s0188-4409(03)00076-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Angiotensin converting enzyme (ACE) inhibitors and angiotensin II AT1-receptor antagonists prolong survival in experimental postischemic heart failure (CHF) in rats. The aim of this study was to investigate whether potential beneficial effects of early and long-term therapy with low doses of captopril or losartan occur in hemodynamics and heart morphometry, as well as in infarct size during establishment of CHF after myocardial infarction. METHODS Male Wistar rats were subjected to myocardial infarction by left coronary ligation. Subsequently, 24 h after surgery captopril (2.5 mg/kg/day/28 days) or losartan (3 mg/kg/day/28 days) was administered by mini-osmotic pump release. Hemodynamics, infarct size, and heart morphometry were measured in sham, untreated, and treated operated rats. RESULTS Morphometric and hemodynamic parameters were modified after myocardial infarction indicating hypertrophy of the heart and CHF establishment; however, either captopril or losartan partially avoided hypertrophy. Captopril reverted hemodynamics to sham values, while losartan induced further decrease in systolic blood pressure. Both drugs were able to drastically reduce infarct size produced by myocardial infarction. CONCLUSIONS Data show that early and chronic therapy with low doses of captopril or losartan prevent CHF establishment, probably by limiting extension of infarcted area after coronary occlusion, and suggest AT1 receptor pathway involvement in this pathology.
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Affiliation(s)
- Luisa A Martínez
- Facultad de Estudios Superiores-Cuautitlán, Universidad Nacional Autónoma de México, Mexico City, DF, Mexico
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Rigol M, Heras M, Solanes N, Epelde F, Roig E, Pérez-Villa F, Roqué M, Sanz G. Enalaprilat, losartan and LU 135252 in coronary blood flow regulation. Eur J Clin Invest 2003; 33:363-9. [PMID: 12713448 DOI: 10.1046/j.1365-2362.2003.01160.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND High plasma levels of angiotensin II are found in several pathologies such as hypertension, heart failure and myocardial infarction. The effect of high concentrations of angiotensin II on coronary circulation is not well defined. The aim of the present study was to assess coronary blood flow regulation during tachycardia in the presence of elevated coronary plasma levels of angiotensin II, and the changes induced by ACE inhibition and blockade of angiotensin II and endothelin-A receptors. DESIGN Left anterior coronary artery was catheterized in 38 pigs to infuse the study drugs. Saline was infused for 15 min. Then, the first atrial pacing was performed. The pigs were distributed to: Group 1 (n = 7) angiotensin II; Group 2 (n = 7) enalaprilat + angiotensin II; Group 3 (n = 9) the bradykinin B2 antagonist HOE 140 + enalaprilat + angiotensin II; Group 4 (n = 7) losartan + angiotensin II; and Group 5 (n = 8) endothelin-A receptor antagonist LU 135252 + angiotensin II. After giving these infusions, a second pacing was repeated. RESULTS The increase in coronary blood flow induced by pacing with angiotensin II was reduced from 181 +/- 21% to 116 +/- 37% (P = 0.006 vs. saline). Enalaprilat, losartan and LU 135252 restored the capacity of coronary blood flow to increase during pacing (151 +/- 39%, 162 +/- 35% and 161 +/- 16%, respectively; P = NS, vs. saline), while HOE 140 abolished the effect of enalaprilat. CONCLUSIONS Moderately elevated coronary concentrations of angiotensin II reduced coronary blood flow during pacing. Enalaprilat, losartan and LU 135252 restored the hyperaemic coronary flow to similar values observed with saline. The beneficial effect of ACE inhibition is mediated through an increase in bradykinin.
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Affiliation(s)
- M Rigol
- Institut de Malalties Cardiovasculars, IDIBAPS, Hospital Clínic, Barcelona, Spain.
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9
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Pons S, Fornes P, Hagege AA, Heudes D, Giudicelli JF, Richer C. Survival, haemodynamics and cardiac remodelling follow up in mice after myocardial infarction. Clin Exp Pharmacol Physiol 2003; 30:25-31. [PMID: 12542449 DOI: 10.1046/j.1440-1681.2003.03784.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. In the present study, the time-course, over a 1 year period, of postischaemic dilated cardiomyopathy and/or development of congestive heart failure was investigated in mice in terms of survival and cardiac functional and structural characteristics. 2. C57BL/6 mice with myocardial infarction (MI mice; coronary ligation n = 78) or sham-operated animals (n = 45) were used and echocardiographic, haemodynamic and histomorphometric parameters were assessed at 3, 6 and 12 months post-MI. 3. At 12 months, the survival rate was 70% in MI mice. Left ventricular dysfunction was evidenced by a strong decrease in ejection fraction (EF; -48 and -53% at 6 and 12 months, respectively; both P < 0.05) and an increase in left ventricular end-diastolic pressure (+100% at both 6 and 12 months; both P < 0.05). There was no major worsening in cardiac function between 6 and 12 months, suggesting strong compensatory mechanisms. Cardiac remodelling was observed, characterized by strong left ventricular hypertrophy (+38 and +62% at 6 and 12 months, respectively; both P < 0.05) and dilatation (+53% at 6 months; P < 0.05), but collagen was not significantly increased. Significant correlations were found between EF (echocardiography) and dP/dtmax, between end-diastolic volume (echocardiography) and left ventricular internal perimeter (histomorphometry) and between left ventricular mass (echocardiography) and weight. 4. In conclusion, despite a high survival rate, the MI mouse model displays most of the hallmarks of postischaemic dilated cardiomyopathy and/or congestive heart failure, thus affording the necessary background for the subsequent evaluation of gene manipulation and/or drug effects. In addition, two-dimensional echocardiography appears to be a suitable tool for the long-term follow up of cardiac function and remodelling in this model.
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Affiliation(s)
- S Pons
- Département de Pharmacologie, INSERM E00-01, Faculté de Médecine Paris-Sud, Le Kremlin-Bicêtre, France
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10
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Trabold F, Pons S, Hagege AA, Bloch-Faure M, Alhenc-Gelas F, Giudicelli JF, Richer-Giudicelli C, Meneton P. Cardiovascular phenotypes of kinin B2 receptor- and tissue kallikrein-deficient mice. Hypertension 2002; 40:90-5. [PMID: 12105144 DOI: 10.1161/01.hyp.0000021747.43346.95] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To clarify the role of the kallikrein-kinin system in cardiovascular homeostasis, the systemic and regional hemodynamics of kinin B2 receptor-deficient (B2-/-) and tissue kallikrein-deficient (TK-/-) mice were compared with their wild-type (WT) littermates on a pure C57BL/6 genetic background. B2-/-, TK-/-, and WT adult mice were normotensive and displayed normal hemodynamic (left ventricular [LV] pressure, cardiac output, total peripheral resistance, dP/dt(max)) and echocardiographic (septum and LV posterior wall thickness, LV diameter, LV mass, and LV fractional shortening) parameters. However, heart rate was lower in B2-/- mice compared with TK-/- and WT mice. In addition, B2-/- mice, but not TK-/- mice, exhibited lower coronary and renal blood flows and greater corresponding vascular resistances than did WT mice, indicating a tonic physiological vasodilating effect of bradykinin in these vascular beds. However, maximal coronary vasodilatation capacity, estimated after dipyridamole infusion, was similar in the 3 groups of mice. B2-/- mice were significantly more sensitive than were TK-/- mice to the vasoconstrictor effects of angiotensin II and norepinephrine. Finally, renin mRNA levels were significantly greater in B2-/- mice and smaller in TK-/- mice compared with WT mice. Taken together, these results indicate that under basal conditions, the kinin B2 receptor is not an important determinant of blood pressure in mice but is involved in the control of regional vascular tone in the coronaries and the kidneys. The phenotypic differences observed between TK-/- and B2-/- mice could be underlain by tissue kallikrein kinin-independent effect and/or kinin B1 receptor activation.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Blotting, Northern
- Bradykinin/pharmacology
- Cardiac Output/drug effects
- Cardiac Output/physiology
- Cardiovascular Physiological Phenomena/drug effects
- Dose-Response Relationship, Drug
- Female
- Genotype
- Heart Ventricles/drug effects
- Hemodynamics/drug effects
- Homeostasis/genetics
- Kallikreins/deficiency
- Kallikreins/genetics
- Ketamine/pharmacology
- Kidney/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Norepinephrine/pharmacology
- Phenotype
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Angiotensin, Type 1
- Receptor, Bradykinin B2
- Receptors, Angiotensin/genetics
- Receptors, Bradykinin/deficiency
- Receptors, Bradykinin/genetics
- Regional Blood Flow/drug effects
- Renin/genetics
- Ventricular Function
- Xylazine/pharmacology
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Affiliation(s)
- Fabien Trabold
- Département de Pharmacologie, Faculté de Médecine Paris-Sud, INSERM 00-01, Le Kremlin-Bicêtre, France
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Nikolaidis LA, Doverspike A, Huerbin R, Hentosz T, Shannon RP. Angiotensin-converting enzyme inhibitors improve coronary flow reserve in dilated cardiomyopathy by a bradykinin-mediated, nitric oxide-dependent mechanism. Circulation 2002; 105:2785-90. [PMID: 12057995 DOI: 10.1161/01.cir.0000017433.90061.2e] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND ACE inhibitors have been used extensively in heart failure, where they induce systemic vasodilatation. ACE inhibitors have also been shown to reduce ischemic events after myocardial infarction, although their mechanisms of action on the coronary circulation are less well understood. The purpose of the present study was to determine the effects and the mechanism of action of the ACE inhibitor enalaprilat and the AT1 antagonist losartan on regional myocardial perfusion and coronary flow and vasodilator reserve in conscious dogs with pacing-induced dilated cardiomyopathy (DCM). METHODS AND RESULTS Twenty-seven conscious, chronically instrumented dogs were studied during advanced stages of dilated cardiomyopathy, which was induced by rapid pacing. Enalaprilat (1.25 mg IV) improved transmural distribution (endocardial/epicardial ratio) at rest (baseline, 0.91+/-0.11; enalaprilat, 1.02+/-0.07 mL/min per g; P<0.05) and during atrial pacing (baseline, 0.82+/-0.11; enalaprilat, 0.98+/-0.07; P<0.05). Enalaprilat also restored subendocardial coronary flow reserve (CFR) (baseline CFR, 1.89+/-0.11; enalaprilat CFR, 2.74+/-0.33; P<0.05) in DCM. These effects were abolished by pretreatment with the NO synthase inhibitor nitro-L-arginine. The effects were recapitulated by the bradykinin(2) receptor agonist cereport but not by the AT1 antagonist losartan. CONCLUSIONS The ACE inhibitor enalaprilat improves transmural myocardial perfusion at rest and after chronotropic stress and restores impaired subendocardial coronary flow and vasodilator reserve in DCM. The effects of enalaprilat were bradykinin mediated and NO dependent and were not recapitulated by losartan. These data suggest beneficial effects of ACE inhibitors on the coronary circulation in DCM that are not shared by AT1 receptor antagonists.
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Affiliation(s)
- Lazaros A Nikolaidis
- Cardiovascular Research Institute, Department of Medicine, Allegheny General Hospital, Pittsburgh, Pa 15212, USA
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12
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Pierce JD, Clancy RL, Smith-Blair N, Kraft R. Treatment and prevention of diaphragm fatigue using low-dose dopamine. Biol Res Nurs 2002; 3:140-9. [PMID: 12003442 DOI: 10.1177/1099800402003003004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is increasing evidence that diaphragm fatigue is a major cause of failure in weaning patients from mechanical ventilation. Patients in intensive care units are often administered dopamine to improve renal blood flow without regard to its effect on diaphragm blood flow. The aim of this study was to investigate if intravenous low-dose dopamine, equivalent to the dose used in intensive care units, can treat and prevent diaphragm fatigue. Diaphragm fatigue was produced in anesthetized rats by inspiratory resistance loading (IRL). The effect on diaphragm shortening, diaphragm blood flow, and aortic blood flow was determined. When diaphragm fatigue was attained, group I was given saline for 30 min while maintaining IRL. At the time of diaphragm fatigue, group II was given low-dose dopamine (2 microg/kg/min) for 30 min while maintaining IRL. In group III, dopamine administration was started before and continued throughout the period of IRL. Administering dopamine after the development of diaphragm fatigue (group II) increased diaphragm performance as measured by increased diaphragm shortening and was accompanied by an increased diaphragm blood flow. Administering dopamine prior to and throughout IRL (group III) prevented diaphragm fatigue. Low-dose dopamine can prevent and/or reverse diaphragm fatigue in rats without a significant change in aortic blood flow. This effect of dopamine may be due to increased oxygen delivery associated with the increased diaphragm blood flow, resulting in less free radical formation and thus less muscle damage.
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Affiliation(s)
- Janet D Pierce
- School of Nursing, University of Kansas Medical Center, Kansas City 66160-7502, USA.
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