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El-Sayed SS, Zakaria MNM, Abdel-Ghany RH, Abdel-Rahman AA. Cystathionine-γ lyase-derived hydrogen sulfide mediates the cardiovascular protective effects of moxonidine in diabetic rats. Eur J Pharmacol 2016; 783:73-84. [PMID: 27138707 DOI: 10.1016/j.ejphar.2016.04.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/24/2016] [Accepted: 04/28/2016] [Indexed: 12/13/2022]
Abstract
Blunted cystathionine-γ lyase (CSE) activity (reduced endogenous H2S-level) is implicated in hypertension and myocardial dysfunction in diabetes. Here, we tested the hypothesis that CSE derived H2S mediates the cardiovascular protection conferred by the imidazoline I1 receptor agonist moxonidine in a diabetic rat model. We utilized streptozotocin (STZ; 55mg/kg i.p) to induce diabetes in male Wistar rats. Four weeks later, STZ-treated rats received vehicle, moxonidine (2 or 6mg/kg; gavage), CSE inhibitor DL-propargylglycine, (37.5mg/kg i.p) or DL-propargylglycine with moxonidine (6mg/kg) for 3 weeks. Moxonidine improved the glycemic state, and reversed myocardial hypertrophy, hypertension and baroreflex dysfunction in STZ-treated rats. Ex vivo studies revealed that STZ caused reductions in CSE expression/activity, H2S and nitric oxide (NO) levels and serum adiponectin and elevations in myocardial imidazoline I1 receptor expression, p38 and extracellular signal-regulated kinase, ERK1/2, phosphorylation and lipid peroxidation (expressed as malondialdehyde). Moxonidine reversed these biochemical responses, and suppressed the expression of death associated protein kinase-3. Finally, pharmacologic CSE inhibition (DL-propargylglycine) abrogated the favorable cardiovascular, glycemic and biochemical responses elicited by moxonidine. These findings present the first evidence for a mechanistic role for CSE derived H2S in the glycemic control and in the favorable cardiovascular effects conferred by imidazoline I1 receptor activation (moxonidine) in a diabetic rat model.
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Affiliation(s)
- Shaimaa S El-Sayed
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
| | - Mohamed N M Zakaria
- Department of Pharmacology and Toxicology, Zagazig University, Zagazig, Egypt
| | - Rasha H Abdel-Ghany
- Department of Pharmacology and Toxicology, Zagazig University, Zagazig, Egypt
| | - Abdel A Abdel-Rahman
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
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Kang YM, Yang Q, Yu XJ, Qi J, Zhang Y, Li HB, Su Q, Zhu GQ. Hypothalamic paraventricular nucleus activation contributes to neurohumoral excitation in rats with heart failure. Regen Med Res 2014; 2:2. [PMID: 25984330 PMCID: PMC4422478 DOI: 10.1186/2050-490x-2-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/24/2013] [Indexed: 02/07/2023] Open
Abstract
Heart failure (HF) is a serious cardiovascular disease and is characterized by exaggerated sympathetic activity. In this paper, we review these limited studies, with particular emphasis on examining the role of the paraventricular nucleus (PVN) in the neurohumoral excitation in HF. The PVN is an important neuroendocrine and preautonomic output nucleus, and is considered as the important central site for integration of sympathetic nerve activity. Accumulating evidences demonstrate that a number of neurohumoral processes are involved in the pathophysiology of HF, such as renin-angiotensin system (RAS), proinflammatory cytokines (PICs), neurotransmitters, and reactive oxygen species (ROS). Recent studies about neurohumoral regulation indicate that angiotensin II type1 receptor (AT1-R) is the important product mediated by cytoplasmic nuclear factor-kappa B (NF-κB) which is up-regulated along with elevated PICs and angiotensin II (ANG II) in the PVN of HF rats. These findings suggest that the NF-κB mediates the cross-talk between RAS and PICs in the PVN in HF. The further studies indicate that the interaction between AT1-R and NF-κB in the PVN contributes to oxidative stress and sympathoexcitation by modulating neurotransmitters in heart failure, and the superoxide activates NF-κB in the PVN and contributes to neurohumoral excitation. In conclusion, the neurohumoral excitation in HF is based on the interaction of RAS, PICs, ROS, NF-κB and neurotransmitters in the PVN; and the activated NF-κB in the PVN modulates the neurotransmitters and contributes to sympathoexcitation in rats with heart failure.
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Affiliation(s)
- Yu-Ming Kang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Qing Yang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Xiao-Jing Yu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Jie Qi
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Yan Zhang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Hong-Bao Li
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Qing Su
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an Jiaotong University Cardiovascular Research Center, Xi'an, 710061 China
| | - Guo-Qing Zhu
- Department of Physiology, Nanjing Medical University, Nanjing, 210029 China
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Karlafti EF, Hatzitolios AI, Karlaftis AF, Baltatzi MS, Koliakos GG, Savopoulos CG. Effects of moxonidine on sympathetic nervous system activity: An update on metabolism, cardio, and other target-organ protection. J Pharm Bioallied Sci 2013; 5:253-6. [PMID: 24302832 PMCID: PMC3831737 DOI: 10.4103/0975-7406.120067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 12/23/2012] [Accepted: 06/10/2013] [Indexed: 01/08/2023] Open
Abstract
Moxonidine is the newest, second-generation, centrally acting antihypertensive agent. It has selective agonist activity at imidazoline I1 receptors and less adverse effects than the other centrally acting drugs. This fact authorizes the frequent use of moxonidine in clinical practice, as monotherapy or in combination with other antihypertensive agents. Also, moxonidine has beneficial effects in obese and metabolic syndrome and in target-organs, such as heart and kidneys.
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Affiliation(s)
- Eleni F Karlafti
- Department of Internal Medicine, AHEPA Hospital, Thessaloniki, Greece
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Honda N, Hirooka Y, Ito K, Matsukawa R, Shinohara K, Kishi T, Yasukawa K, Utsumi H, Sunagawa K. Moxonidine-induced central sympathoinhibition improves prognosis in rats with hypertensive heart failure. J Hypertens 2013; 31:2300-8; discussion 2308. [DOI: 10.1097/hjh.0b013e328364a2a1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Evaluation of antioxidant and immunity function of tetramethylpyrazine phosphate tablets in vivo. Molecules 2012; 17:5412-21. [PMID: 22569420 PMCID: PMC6268603 DOI: 10.3390/molecules17055412] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 04/28/2012] [Accepted: 04/28/2012] [Indexed: 12/29/2022] Open
Abstract
The aim of the study was to determine the effect of tetramethylpyrazine phosphate tablets (TPT), a Chinese medicine used for cardiovascular disease, on immunity activity and oxidative injury in rats. Heart failure (HF) was induced by isoproterenol (ISO). After the animal model was established, the rats were administered the TPT by gavage (once a day). The results indicated that TPT improved left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), ±dP/dt, heart weight/body weight. TPT could decrease the levels of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). Furthermore, it also could raise the activities of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but reduce malonyldialdehyde (MDA) level. The results indicated that TPT improved cardiac function and myocardial fibrosis from myocardial injury, and this cardioprotection might be attributed to a reduction of oxidative stress and regulation of inflammation mediators.
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Aceros H, Farah G, Cobos-Puc L, Stabile AM, Noiseux N, Mukaddam-Daher S. Moxonidine improves cardiac structure and performance in SHR through inhibition of cytokines, p38 MAPK and Akt. Br J Pharmacol 2012; 164:946-57. [PMID: 21426316 DOI: 10.1111/j.1476-5381.2011.01355.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Regression of left ventricular hypertrophy by moxonidine, a centrally acting sympatholytic imidazoline compound, results from a sustained reduction of DNA synthesis and transient stimulation of DNA fragmentation. Because apoptosis of cardiomyocytes may lead to contractile dysfunction, we investigated in spontaneously hypertensive rats (SHR), time- and dose-dependent effects of in vivo moxonidine treatment on cardiac structure and function as well as on the inflammatory process and signalling proteins involved in cardiac cell survival/death. EXPERIMENTAL APPROACH 12 week old SHR received moxonidine at 0, 100 and 400 µg·kg(-1)·h(-1) , s.c., for 1 and 4 weeks. Cardiac function was evaluated by echocardiography; plasma cytokines were measured by elisa and hearts were collected for histological assessment of fibrosis and measurement of cardiac proteins by Western blotting. Direct effects of moxonidine on cardiac cell death and underlying mechanisms were investigated in vitro by flow cytometry and Western blotting. KEY RESULTS After 4 weeks, the sub-hypotensive dose of moxonidine (100 µg) reduced heart rate and improved global cardiac performance, reduced collagen deposition, regressed left ventricular hypertrophy, inhibited Akt and p38 MAPK phosphorylation, and attenuated circulating and cardiac cytokines. The 400 µg dose resulted in similar effects but of a greater magnitude, associated with blood pressure reduction. In vitro, moxonidine inhibited norepinephrine-induced neonatal cardiomyocyte mortality but increased fibroblast mortality, through I(1)-receptor activation and differential effects on downstream Akt and p38 MAPK. CONCLUSIONS AND IMPLICATIONS While the antihypertensive action of centrally acting imidazoline compounds is appreciated, new cardiac-selective I(1)-receptor agonists may confer additional benefit.
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Affiliation(s)
- H Aceros
- Centre Hospitalier de L'Université de Montréal Research Center, Québec, Canada
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Kang YM, Zhang AQ, Zhao XF, Cardinale JP, Elks C, Cao XM, Zhang ZW, Francis J. Paraventricular nucleus corticotrophin releasing hormone contributes to sympathoexcitation via interaction with neurotransmitters in heart failure. Basic Res Cardiol 2011; 106:473-83. [PMID: 21287352 PMCID: PMC3118407 DOI: 10.1007/s00395-011-0155-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 12/20/2010] [Accepted: 01/21/2011] [Indexed: 01/22/2023]
Abstract
Recent studies indicate that systemic administration of tumor necrosis factor (TNF)-α induces increases in corticotrophin releasing hormone (CRH) and CRH type 1 receptors in the hypothalamic paraventricular nucleus (PVN). In this study, we explored the hypothesis that CRH in the PVN contributes to sympathoexcitation via interaction with neurotransmitters in heart failure (HF). Sprague-Dawley rats with HF or sham-operated controls (SHAM) were treated for 4 weeks with a continuous bilateral PVN infusion of the selective CRH-R1 antagonist NBI-27914 or vehicle. Rats with HF had higher levels of glutamate, norepinephrine (NE) and tyrosine hydroxylase (TH), and lower levels of gamma-aminobutyric acid (GABA) and the 67-kDa isoform of glutamate decarboxylase (GAD67) in the PVN when compared to SHAM rats. Plasma levels of cytokines, NE, ACTH and renal sympathetic nerve activity (RSNA) were increased in HF rats. Bilateral PVN infusions of NBI-27914 attenuated the decreases in PVN GABA and GAD67, and the increases in RSNA, ACTH and PVN glutamate, NE and TH observed in HF rats. These findings suggest that CRH in the PVN modulates neurotransmitters and contributes to sympathoexcitation in rats with ischemia-induced HF.
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Affiliation(s)
- Yu-Ming Kang
- Department of Physiology and Pathophysiology, Xi’an Jiaotong University School of Medicine, Xi’an 710061, China
| | - Ai-Qun Zhang
- Institute of Hepatobiliary Surgery, General Hospital of Chinese People’s Liberation Army, Beijing, China
| | - Xiu-Fang Zhao
- Department of Internal Medicine, General Hospital of Chinese People’s Armed Police Forces, Beijing, China
| | - Jeffrey P. Cardinale
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Carrie Elks
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Xi-Mei Cao
- Department of Physiology, Shanxi Medical University, Taiyuan, China
| | - Zhen-Wen Zhang
- Department of Internal Medicine, General Hospital of Chinese People’s Armed Police Forces, Beijing, China
| | - Joseph Francis
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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Stabile AM, Aceros H, Stockmeyer K, Abdel Rahman AA, Noiseux N, Mukaddam-Daher S. Functional and molecular effects of imidazoline receptor activation in heart failure. Life Sci 2011; 88:493-503. [PMID: 21277868 DOI: 10.1016/j.lfs.2011.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 12/05/2010] [Accepted: 12/27/2010] [Indexed: 12/17/2022]
Abstract
AIMS Heart failure is a progressive deterioration in heart function associated with overactivity of the sympathetic nervous system. The benefit of inhibition of sympathetic activity by moxonidine, a centrally acting imidazoline receptor agonist, was questioned based on the outcome of a failing clinical trial. The following studies measured cardiac structure and hemodynamics and mechanisms underlying moxonidine-induced changes, in cardiomyopathic hamsters, where the stage of the disease, dose, and compliance were controlled. MAIN METHODS Male BIO 14.6 hamsters (6 and 10 months old, with moderate and advanced heart failure, respectively) received moxonidine at 2 concentrations: low (2.4 mg/kg/day) and high (9.6 mg/kg/day), or vehicle, subcutaneously, for 1month. Cardiac function was measured by echocardiography, plasma and hearts were collected for histological determination of fibrosis and apoptosis, as well as for measurement cytokines by Elisa and cardiac proteins by Western blotting. KEY FINDINGS Compared to age-matched vehicle-treated BIO 14.6, moxonidine did not reduce blood pressure but significantly reduced heart rate and improved cardiac performance. Moxonidine exerted anti-apoptotic effect with differential inflammatory/anti-inflammatory responses that culminate in attenuated cardiac apoptosis and fibrosis and altered protein expression of collagen types. Some effects were observed regardless of treatment onset, although the changes were more significant in the younger group. Interestingly, moxonidine resulted in upregulation of cardiac imidazoline receptors. SIGNIFICANCE These studies imply that in addition to centrally mediated sympathetic inhibition, the effects of moxonidine may, at least in part, be mediated by direct actions on the heart. Further investigation of imidazolines/imidazoline receptors in cardiovascular diseases is warranted.
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Affiliation(s)
- Angelita Maria Stabile
- Centre Hospitalier de L'Université de Montréal Research Center (CRCHUM), Montreal, QC, Canada
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9
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Igawa A, Nozawa T, Fujii N, Kato BI, Asanoi H, Inoue H. Long-term treatment with low-dose, but not high-dose, guanethidine improves ventricular function and survival of rats with heart failure after myocardial infarction. J Am Coll Cardiol 2003; 42:541-8. [PMID: 12906986 DOI: 10.1016/s0735-1097(03)00650-8] [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: 10/27/2022]
Abstract
OBJECTIVES We sought to evaluate the effects of various doses of guanethidine, a sympathoinhibitory drug, on ventricular function and survival in chronic heart failure (CHF) after myocardial infarction (MI) in rats. BACKGROUND Direct inhibition of sympathetic outflow by a sympathoinhibitory drug might be an effective approach to therapy of CHF. However, recent clinical trials suggest that excessive suppression of sympathetic activity has an adverse effect on outcome. It remains unclear whether the beneficial effects of the sympathoinhibitory drug would be modified by its dosage. METHODS Three doses of guanethidine (low-dose [LG], 1 mg/kg/day; medium-dose, 3 mg/kg/day; high-dose, 10 mg/kg/day) were administered via an osmotic mini-pump for 4 weeks. Hemodynamics, left ventricular (LV) diameters, plasma and myocardial norepinephrine (NE) levels, and survival were determined for four weeks after MI. RESULTS As compared with MI rats receiving vehicle, LG suppressed LV dilation (9.2 +/- 0.9 mm vs. 11.0 +/- 0.8 mm, p < 0.05) and improved LV fractional shortening (25.0 +/- 4.5% vs. 16.4 +/- 4.7%, p < 0.05) in association with a reduction of plasma NE levels (520 +/- 250 pg/ml vs. 1,000 +/- 570 pg/ml, p < 0.05), but not with a significant reduction of noninfarcted myocardial NE levels (154 +/- 71 ng/g vs. 207 +/- 71 ng/g). Low-dose guanethidine reduced 24-h (6%) and 28-day mortality (6%), as compared with untreated MI rats (36% and 52%, respectively). High-dose guanethidine also reduced 24-h mortality (12%) but increased 28-day mortality (91%), in association with a depletion of myocardial NE. Medium-dose guanethidine had no beneficial effects on LV hemodynamics or long-term survival. CONCLUSIONS These results indicate that the dosage of the sympathoinhibitory drug might be quite important for the treatment of CHF.
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Affiliation(s)
- Akihiko Igawa
- Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama, Japan
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Arabia AM, Catapano L, Storini C, Perego C, De Luigi A, Head GA, De Simoni MG. Impaired central stress-induced release of noradrenaline in rats with heart failure: a microdialysis study. Neuroscience 2002; 114:591-9. [PMID: 12220562 DOI: 10.1016/s0306-4522(02)00337-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sympathetic hyperactivity in rats with heart failure is associated with increased extracellular noradrenaline in the hypothalamic paraventricular nucleus at rest. However, it is unknown how this nucleus responds to stressful stimuli. In the present study we therefore examined the basal and stress-induced release of noradrenaline in the paraventricular nucleus of conscious Sprague-Dawley rats with heart failure measured by in vivo microdialysis. Basal noradrenaline concentration in the paraventricular nucleus of rats with heart failure was more than double that in sham-operated controls. Immobilization stress decreases noradrenaline levels in the paraventricular nucleus of rats with heart failure to 57% of baseline, while it increased in sham-operated controls to 228%. However, serum corticosterone was similarly elevated at 30 and 90 min post-stress in both experimental groups. We have shown that heart failure causes an impairment of the central noradrenergic system's response to acute sympatho-excitation but does not affect the hypothalamo-pituitary-adrenocortical response.
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Affiliation(s)
- A M Arabia
- Inflammation and Nervous System Disease Laboratory, Istituto di Ricerche Farmacologiche Mario Negri, Milan 20157, Italy.
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Brede M, Wiesmann F, Jahns R, Hadamek K, Arnolt C, Neubauer S, Lohse MJ, Hein L. Feedback inhibition of catecholamine release by two different alpha2-adrenoceptor subtypes prevents progression of heart failure. Circulation 2002; 106:2491-6. [PMID: 12417548 DOI: 10.1161/01.cir.0000036600.39600.66] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Elevated plasma norepinephrine levels are associated with increased mortality in patients and in animal models with chronic heart failure. To test which alpha2-adrenoceptor subtypes operate as presynaptic inhibitory receptors to control norepinephrine release in heart failure, we investigated the response of gene-targeted mice lacking alpha2-adrenoceptor subtypes (alpha2-KO) to chronic left ventricular pressure overload. In addition, we determined the functional consequences of genetic variants of alpha2-adrenoceptors in human patients with chronic heart failure. METHODS AND RESULTS Cardiac pressure overload was induced by transverse aortic constriction. Three months after aortic banding, survival was dramatically reduced in alpha2A-KO (52%) and alpha2C-KO (47%) mice compared with wild-type and alpha2B-deficient (86%) animals. Excess mortality in alpha2A- and alpha2C-KO strains was attributable to heart failure with enhanced left ventricular hypertrophy and fibrosis and elevated circulating catecholamines. The clinical importance of this finding is emphasized by the fact that heart failure patients with a dysfunctional variant of the alpha2C-adrenoceptor had a worse clinical status and decreased cardiac function as determined by invasive catheterization and by echocardiography. CONCLUSIONS Our results indicate an essential function of alpha2A- and alpha2C-adrenoceptors in the prevention of heart failure progression in mice and human patients. Identification of heart failure patients with genetic alpha2-adrenoceptor variants as well as new alpha2-receptor subtype-selective drugs may represent novel therapeutic strategies in chronic heart failure and other diseases with enhanced sympathetic activation.
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Affiliation(s)
- Marc Brede
- Institut für Pharmakologie und Toxikologie, Universität Würzburg, Germany
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12
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Van Kerckhoven R, Saxena PR, Schoemaker RG. Restored capillary density in spared myocardium of infarcted rats improves ischemic tolerance. J Cardiovasc Pharmacol 2002; 40:370-80. [PMID: 12198323 DOI: 10.1097/00005344-200209000-00006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Myocardial infarction (MI)-induced hypertrophy is associated with a decreased capillary density, which may negatively affect ischemic tolerance of the spared myocardium. The current study investigated the effects of moxonidine, a centrally acting sympatholytic, on left ventricular (LV) hypertrophy and capillary density in relation to sensitivity to ischemia in infarcted hearts. Infarcted rats were randomized to receive 3 or 6 mg/kg/d of moxonidine from 1 to 21 days after MI. LV hypertrophy after MI was indicated by increased ventricular to body weight ratio and was significantly inhibited by moxonidine. Histologic analysis revealed that MI-induced concentric hypertrophy of the spared myocardium, as indicated by almost double cross-sectional area of Gomori-stained myocytes, was completely prevented by 6 mg/kg/d of moxonidine. This effect was accompanied by a a restored number of lectin-stained capillaries per tissue area. However, capillary-to-myocyte ratio was similar in all groups. LV dysfunction after MI, measured in isolated perfused hearts, was confirmed by decreased LV systolic pressure and +dP/dtmax and was not affected by moxonidine. Low-flow ischemia, induced by lowering perfusion pressure from 85 to 15 mm Hg for 30 min, resulted in a further reduction of cardiac perfusion compared with sham rats, which was normalized with 6 mg/kg/d of moxonidine. Ischemic sensitivity in MI hearts, as reflected by increased maximal coronary flow during reperfusion, was reduced with moxonidine. This was further supported by substantially lower purines and lactate concentrations in the coronary effluent during ischemia. These results indicate that moxonidine-induced prevention of hypertrophy may preserve capillary density without affecting capillary number, thereby improving ischemic tolerance of the spared myocardium.
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Affiliation(s)
- Roeland Van Kerckhoven
- Deparment of Pharacology, Faculty of Medicine and Health Sciences, Erasmus University, Rotterdam, The Netherlands.
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Liu JL, Pliquett RU, Brewer E, Cornish KG, Shen YT, Zucker IH. Chronic endothelin-1 blockade reduces sympathetic nerve activity in rabbits with heart failure. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1906-13. [PMID: 11353699 DOI: 10.1152/ajpregu.2001.280.6.r1906] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Endothelin-1 (ET-1) is elevated in chronic heart failure (CHF). In this study, we determined the effects of chronic ET-1 blockade on renal sympathetic nerve activity (RSNA) in conscious rabbits with pacing-induced CHF. Rabbits were chronically paced at 320–340 beats/min for 3–4 wk until clinical and hemodynamic signs of CHF were present. Resting RSNA and arterial baroreflex control of RSNA were determined. Responses were determined before and after the ET-1 antagonist L-754,142 (a combined ETA and ETB receptor antagonist, n = 5) was administered by osmotic minipump infusion (0.5 mg · kg−1 · h−1 for 48 h). In addition, five rabbits with CHF were treated with the specific ETA receptor antagonist BQ-123. Baseline RSNA (expressed as a percentage of the maximum nerve activity during sodium nitroprusside infusion) was significantly higher (58.3 ± 4.9 vs. 27.0 ± 1.0, P < 0.001), whereas baroreflex sensitivity was significantly lower in rabbits with CHF compared with control (3.09 ± 0.19 vs. 6.04 ± 0.73, P < 0.001). L-754,142 caused a time-dependent reduction in arterial pressure and RSNA in rabbits with CHF. In addition, BQ-123 caused a reduction in resting RSNA. For both compounds, RSNA returned to near control levels 24 h after removal of the minipump. These data suggest that ET-1 contributes to sympathoexcitation in the CHF state. Enhancement of arterial baroreflex sensitivity may further contribute to sympathoinhibition after ET-1 blockade in heart failure.
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Affiliation(s)
- J L Liu
- Department of Physiology and Biophysics, University of Nebraska College of Medicine, Omaha, Nebraska 68198-4575, USA
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14
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Abstract
Initially it was considered that moxonidine, like clonidine, acted at central (2)-adrenoceptors to reduce blood pressure. With the characterisation of imidazoline binding sites distinct from (2)-adrenoceptors, the consensus became that moxonidine was acting predominantly at imidazoline I(1) receptors in the rostral ventrolateral medulla to lower blood pressure. Moxonidine acts at prejunctional (2)-adrenoceptors on sympathetic nerve endings to decrease noradrenaline release and this may contribute to its ability to lower blood pressure. The predominant site of action of moxonidine may also depend on route of administration, with imidazoline I(1) receptors being predominant after central, and (2)-adrenoceptors predominant after systemic administration. The controversy over the mechanism and site of action with moxonidine is ongoing. In animal models, moxonidine lowers blood pressure, reduces cardiac hypertrophy and remodelling, reduces cardiac arrhythmias and increases blood flow in cerebral ischaemia. Moxonidine also has beneficial effects in animal models of diabetes and kidney disease. Moxonidine increases sodium and water excretion in rats, but not humans. Animal studies indicate that moxonidine may be useful in the treatment of glaucoma by reducing intra-ocular pressure. Animal studies show that moxonidine may also be effective in pain and in ethanol withdrawal. In humans, the pharmacokinetics of moxonidine are of the one-compartment model with first-order absorption. Renal elimination is the major route of elimination and individual titration of moxonidine is needed in patients with renal impairment. There is overwhelming evidence that moxonidine is a safe and effective antihypertensive. A large clinical trial of moxonidine in heart failure, MOXCON, was stopped because of excessive deaths in the moxonidine group. Moxonidine should not be used in patients with heart failure, but there are no obvious reasons to stop its use as an antihypertensive, or its development for other clinical uses.
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Affiliation(s)
- S A Doggrell
- Doggrell Biomedical Communications, 47 Caronia Crescent, Lynfield, Auckland, New Zealand
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