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Gurel NZ, Sudarshan KB, Hadaya J, Karavos A, Temma T, Hori Y, Armour JA, Kember G, Ajijola OA. Metrics of high cofluctuation and entropy to describe control of cardiac function in the stellate ganglion. eLife 2022; 11:e78520. [PMID: 36426848 PMCID: PMC9815826 DOI: 10.7554/elife.78520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022] Open
Abstract
Stellate ganglia within the intrathoracic cardiac control system receive and integrate central, peripheral, and cardiopulmonary information to produce postganglionic cardiac sympathetic inputs. Pathological anatomical and structural remodeling occurs within the neurons of the stellate ganglion (SG) in the setting of heart failure (HF). A large proportion of SG neurons function as interneurons whose networking capabilities are largely unknown. Current therapies are limited to targeting sympathetic activity at the cardiac level or surgical interventions such as stellectomy, to treat HF. Future therapies that target the SG will require understanding of their networking capabilities to modify any pathological remodeling. We observe SG networking by examining cofluctuation and specificity of SG networked activity to cardiac cycle phases. We investigate network processing of cardiopulmonary transduction by SG neuronal populations in porcine with chronic pacing-induced HF and control subjects during extended in-vivo extracellular microelectrode recordings. We find that information processing and cardiac control in chronic HF by the SG, relative to controls, exhibits: (i) more frequent, short-lived, high magnitude cofluctuations, (ii) greater variation in neural specificity to cardiac cycles, and (iii) neural network activity and cardiac control linkage that depends on disease state and cofluctuation magnitude.
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Affiliation(s)
- Nil Z Gurel
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
| | - Koustubh B Sudarshan
- Department of Engineering Mathematics and Internetworking, Dalhousie UniversityNova ScotiaCanada
| | - Joseph Hadaya
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
- UCLA Molecular, Cellular, and Integrative Physiology ProgramLos AngelesUnited States
| | - Alex Karavos
- Department of Engineering Mathematics and Internetworking, Dalhousie UniversityNova ScotiaCanada
| | - Taro Temma
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
| | - Yuichi Hori
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
| | - J Andrew Armour
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
| | - Guy Kember
- Department of Engineering Mathematics and Internetworking, Dalhousie UniversityNova ScotiaCanada
| | - Olujimi A Ajijola
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of ExcellenceLos AngelesUnited States
- UCLA Molecular, Cellular, and Integrative Physiology ProgramLos AngelesUnited States
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2
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de Paula Facioli T, Vieira Philbois S, Augusto Aguilar B, Catarine Veiga A, Celso Dutra de Souza H. Combined effects of angiotensin receptor blocker use and physical training in hypertensive men. Clin Exp Hypertens 2022; 44:372-381. [PMID: 35343339 DOI: 10.1080/10641963.2022.2055763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Pharmacological (angiotensin II receptor type 1 receptor blocker use) and non-pharmacological treatment (physical aerobic exercise) are important strategies to reduces blood pressure and control arterial hypertension; however, only few clinical studies have evaluated their combined effects on autonomic cardiovascular control. Therefore, we investigated the effect of a combination intervention that involved losartan administration and physical aerobic training on autonomic cardiovascular control. METHODS Thirty-two men (aged 40 to 60 years) were assigned into two groups: normotensive group, without any pharmacological treatment (NG, N = 16), or hypertensive group, with losartan administration (HG, N = 16). They underwent a physical aerobic training for 16 weeks, thrice a week. Hemodynamic parameters, heart rate variability (HRV), blood pressure variability, and spontaneous baroreflex sensitivity (BRS) were measured before and after training. RESULTS Before training, both the groups showed similar values of hemodynamic parameters. However, the HG showed decreased BRS and HRV, characterized by reduction in sympathetic (p = .02) and vagal (p < .001) modulation. After training, the NG exhibited decreased heart rate (HR) at rest (p < .001), whereas the HG showed decreased HR at rest (p < .001) and blood pressure (BP) (p = .001). The HG showed decreased sympathetic modulation (p = .02) and increased BRS (p < .001) and vagal modulation (p < .001), but HRV (p < .001) and BRS gain (p < .001) remained significantly lower when compared to the NG. CONCLUSIONS Physical aerobic training was essential to improve the BRS and HRV cardiac autonomic modulation in the HG. However, it was not sufficient to normalize the analyzed autonomic parameters.
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Affiliation(s)
- Tábata de Paula Facioli
- Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Stella Vieira Philbois
- Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Bruno Augusto Aguilar
- Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Ana Catarine Veiga
- Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Hugo Celso Dutra de Souza
- Department of Health Sciences, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Wu P, Vaseghi M. The autonomic nervous system and ventricular arrhythmias in myocardial infarction and heart failure. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2020; 43:172-180. [PMID: 31823401 DOI: 10.1111/pace.13856] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 11/25/2019] [Accepted: 12/05/2019] [Indexed: 12/20/2022]
Abstract
Ventricular arrhythmias (VA) can range in presentation from asymptomatic to cardiac arrest and sudden cardiac death (SCD). Sustained ventricular tachycardias/ventricular fibrillation (VT/VF) are a common cause of SCD in the setting of myocardial infarction (MI) and heart failure. A particularly arrhythmogenic cardiac syncytia in these conditions can be attributed to both sympathetic activation and parasympathetic dysfunction, while appropriate neuromodulation has the potential to reduce occurrence of VT/VF. In this review, we outline the components of the autonomic nervous system that play an important role in normal cardiac electrophysiology and function. In addition, we discuss changes that occur in the setting of cardiac disease including adverse neural remodeling and neurohormonal activation which significantly contribute to propensity for VT/VF. Finally, we review neuromodulation strategies to mitigate VT/VF which predominantly rely on increasing parasympathetic drive and blockade of sympathetic neurotransmission.
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Affiliation(s)
- Perry Wu
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of Excellence, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Marmar Vaseghi
- UCLA Cardiac Arrhythmia Center and UCLA Neurocardiology Research Program of Excellence, David Geffen School of Medicine at UCLA, Los Angeles, California
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Dalmasso C, Leachman JR, Osborn JL, Loria AS. Sensory signals mediating high blood pressure via sympathetic activation: role of adipose afferent reflex. Am J Physiol Regul Integr Comp Physiol 2019; 318:R379-R389. [PMID: 31868518 DOI: 10.1152/ajpregu.00079.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Blood pressure regulation in health and disease involves a balance between afferent and efferent signals from multiple organs and tissues. Although there are numerous reviews focused on the role of sympathetic nerves in different models of hypertension, few have revised the contribution of afferent nerves innervating adipose tissue and their role in the development of obesity-induced hypertension. Both clinical and basic research support the beneficial effects of bilateral renal denervation in lowering blood pressure. However, recent studies revealed that afferent signals from adipose tissue, in an adipose-brain-peripheral pathway, could contribute to the increased sympathetic activation and blood pressure during obesity. This review focuses on the role of adipose tissue afferent reflexes and briefly describes a number of other afferent reflexes modulating blood pressure. A comprehensive understanding of how multiple afferent reflexes contribute to the pathophysiology of essential and/or obesity-induced hypertension may provide significant insights into improving antihypertensive therapeutic approaches.
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Affiliation(s)
- Carolina Dalmasso
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Jacqueline R Leachman
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Jeffrey L Osborn
- Department of Biology, College of Arts and Sciences, University of Kentucky, Lexington, Kentucky
| | - Analia S Loria
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, Kentucky
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Ding L, Zhang F, Zhao MX, Ren XS, Chen Q, Li YH, Kang YM, Zhu GQ. Reduced lipolysis response to adipose afferent reflex involved in impaired activation of adrenoceptor-cAMP-PKA-hormone sensitive lipase pathway in obesity. Sci Rep 2016; 6:34374. [PMID: 27694818 PMCID: PMC5046068 DOI: 10.1038/srep34374] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 09/08/2016] [Indexed: 12/26/2022] Open
Abstract
Chemical stimulation of white adipose tissue (WAT) causes adipose afferent reflex (AAR) and sympathetic activation. This study is to investigate the effects of AAR on lipolysis and the mechanisms of attenuated lipolysis response to enhanced AAR in obesity. Obesity was caused by high-fat diet for 12 weeks in rats. AAR was induced by injection of capsaicin into inguinal WAT or electrical stimulation of epididymal WAT afferent nerve. AAR caused sympathetic activation, which was enhanced in obesity rats. AAR increased cAMP levels and PKA activity, promoted hormone sensitive lipase (HSL) and perilipin phosphorylation, and increased lipolysis in WAT, which were attenuated in obesity rats. PKA activity, cAMP, perilipin and β-adrenoceptor levels were reduced, while HSL was upregulated in adipocytes from obesity rats. In primary adipocytes, isoproterenol increased cAMP levels and PKA activity, promoted HSL and perilipin phosphorylation, and increased lipolysis, which were attenuated in obesity rats. The attenuated effects of isoproterenol in adipocytes from obesity rats were prevented by a cAMP analogue dbcAMP. The results indicate that reduced lipolysis response to enhanced AAR in obesity is attributed to the impaired activation of β-adrenoceptor-cAMP-PKA-HSL pathway. Increased cAMP level in adipocytes rectifies the attenuated lipolysis in obesity.
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Affiliation(s)
- Lei Ding
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Feng Zhang
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Ming-Xia Zhao
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Xing-Sheng Ren
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Qi Chen
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Yue-Hua Li
- Department of Pathophysiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Yu-Ming Kang
- Department of Physiology and Pathophysiology, Cardiovascular Research Center, Xi’an Jiaotong University School of Medicine, Xi’an 710061, China
| | - Guo-Qing Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
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Ardell JL, Andresen MC, Armour JA, Billman GE, Chen PS, Foreman RD, Herring N, O'Leary DS, Sabbah HN, Schultz HD, Sunagawa K, Zucker IH. Translational neurocardiology: preclinical models and cardioneural integrative aspects. J Physiol 2016; 594:3877-909. [PMID: 27098459 DOI: 10.1113/jp271869] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/14/2016] [Indexed: 12/15/2022] Open
Abstract
Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics.
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Affiliation(s)
- J L Ardell
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, CA, USA.,UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, CA, USA
| | - M C Andresen
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA
| | - J A Armour
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, CA, USA.,UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, CA, USA
| | - G E Billman
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - P-S Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - R D Foreman
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - N Herring
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - D S O'Leary
- Department of Physiology, Wayne State University, Detroit, MI, USA
| | - H N Sabbah
- Department of Medicine, Henry Ford Hospital, Detroit, MI, USA
| | - H D Schultz
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - K Sunagawa
- Department of Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - I H Zucker
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
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8
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Mirizzi G, Giannoni A, Ripoli A, Iudice G, Bramanti F, Emdin M, Passino C. Prediction of the Chemoreflex Gain by Common Clinical Variables in Heart Failure. PLoS One 2016; 11:e0153510. [PMID: 27099934 PMCID: PMC4839709 DOI: 10.1371/journal.pone.0153510] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/30/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Peripheral and central chemoreflex sensitivity, assessed by the hypoxic or hypercapnic ventilatory response (HVR and HCVR, respectively), is enhanced in heart failure (HF) patients, is involved in the pathophysiology of the disease, and is under investigation as a potential therapeutic target. Chemoreflex sensitivity assessment is however demanding and, therefore, not easily applicable in the clinical setting. We aimed at evaluating whether common clinical variables, broadly obtained by routine clinical and instrumental evaluation, could predict increased HVR and HCVR. METHODS AND RESULTS 191 patients with systolic HF (left ventricular ejection fraction--LVEF--<50%) underwent chemoreflex assessment by rebreathing technique to assess HVR and HCVR. All patients underwent clinical and neurohormonal evaluation, comprising: echocardiogram, cardiopulmonary exercise test (CPET), daytime cardiorespiratory monitoring for breathing pattern evaluation. Regarding HVR, multivariate penalized logistic regression, Bayesian Model Averaging (BMA) logistic regression and random forest analysis identified, as predictors, the presence of periodic breathing and increased slope of the relation between ventilation and carbon dioxide production (VE/VCO2) during exercise. Again, the above-mentioned statistical tools identified as HCVR predictors plasma levels of N-terminal fragment of proBNP and VE/VCO2 slope. CONCLUSIONS In HF patients, the simple assessment of breathing pattern, alongside with ventilatory efficiency during exercise and natriuretic peptides levels identifies a subset of patients presenting with increased chemoreflex sensitivity to either hypoxia or hypercapnia.
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Affiliation(s)
- Gianluca Mirizzi
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
- * E-mail:
| | - Alberto Giannoni
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Andrea Ripoli
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Giovanni Iudice
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Francesca Bramanti
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Michele Emdin
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
- Scuola Superiore Sant’Anna, Pisa, Italy
| | - Claudio Passino
- Department of Cardiology and Cardiovascular Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy
- Scuola Superiore Sant’Anna, Pisa, Italy
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Shi Z, Wang YF, Wang GH, Wu YL, Ma CL. Paraventricular nucleus is involved in the central pathway of adipose afferent reflex in rats. Can J Physiol Pharmacol 2015; 94:534-41. [PMID: 26963333 DOI: 10.1139/cjpp-2015-0097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increasing evidence indicates a link between sympathetic nervous system activation and obesity, but the underlying mechanisms remain elusive. The adipose afferent reflex (AAR) is a sympathoexcitatory reflex that is activated by afferent neurotransmission from the white adipose tissue (WAT). This study aimed to investigate whether the hypothalamic paraventricular nucleus (PVH) is an important component of the central neurocircuitry of the AAR. In anesthetized rats, the discharge activity of individual PVH neurons was recorded in vivo. Activation of WAT afferents was initiated by capsaicin injection, and the AAR was evaluated by monitoring renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses. The responses of PVH neurons to activation of WAT afferents were evaluated by c-fos immunoreactivity and the discharge activity of individual PVH neurons, which was recorded using extracellular single-unit recording. After activation of WAT afferents, both individual PVH neuron discharge activity and c-fos immunoreactivity increased. Bilateral selective lesions of the neurons in the PVH with kainic acid abolished the AAR. These results indicate that PVH is an important component of the central neurocircuitry of the AAR.
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Affiliation(s)
- Zhen Shi
- a Department of Physiology, Binzhou Medical University, 346 Guanhai Rd., Laishan District, Yantai 264003, China
| | - Yuan-Fang Wang
- b Department of Pharmacology, Binzhou Medical University, Yantai 264003, China
| | - Gui-Hua Wang
- a Department of Physiology, Binzhou Medical University, 346 Guanhai Rd., Laishan District, Yantai 264003, China
| | - Yu-Long Wu
- c Department of Pathogenic Biology, Binzhou Medical University, Yantai 264003, China
| | - Chun-Lei Ma
- a Department of Physiology, Binzhou Medical University, 346 Guanhai Rd., Laishan District, Yantai 264003, China.,d Shandong Province Key Laboratory of Stroke
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Central nervous system circuits modified in heart failure: pathophysiology and therapeutic implications. Heart Fail Rev 2015; 19:759-79. [PMID: 24573960 DOI: 10.1007/s10741-014-9427-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The pathophysiology of heart failure (HF) is characterized by an abnormal activation of neurohumoral systems, including the sympathetic nervous and the renin-angiotensin-aldosterone systems, which have long-term deleterious effects on the disease progression. Perpetuation of this neurohumoral activation is partially dependent of central nervous system (CNS) pathways, mainly involving the paraventricular nucleus of the hypothalamus and some regions of the brainstem. Modifications in these integrative CNS circuits result in the attenuation of sympathoinhibitory and exacerbation of sympathoexcitatory pathways. In addition to the regulation of sympathetic outflow, these central pathways coordinate a complex network of agents with an established pathophysiological relevance in HF such as angiotensin, aldosterone, and proinflammatory cytokines. Central pathways could be potential targets in HF therapy since the current mainstay of HF pharmacotherapy aims primarily at antagonizing the peripheral mechanisms. Thus, in the present review, we describe the role of CNS pathways in HF pathophysiology and as potential novel therapeutic targets.
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11
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Chen WW, Xiong XQ, Chen Q, Li YH, Kang YM, Zhu GQ. Cardiac sympathetic afferent reflex and its implications for sympathetic activation in chronic heart failure and hypertension. Acta Physiol (Oxf) 2015; 213:778-94. [PMID: 25598170 DOI: 10.1111/apha.12447] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 10/22/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
Persistent excessive sympathetic activation greatly contributes to the pathogenesis of chronic heart failure (CHF) and hypertension. Cardiac sympathetic afferent reflex (CSAR) is a sympathoexcitatory reflex with positive feedback characteristics. Humoral factors such as bradykinin, adenosine and reactive oxygen species produced in myocardium due to myocardial ischaemia stimulate cardiac sympathetic afferents and thereby reflexly increase sympathetic activity and blood pressure. The CSAR is enhanced in myocardial ischaemia, CHF and hypertension. The enhanced CSAR at least partially contributes to the sympathetic activation and pathogenesis of these diseases. Nucleus of the solitary tract (NTS), hypothalamic paraventricular nucleus (PVN) and rostral ventrolateral medulla are the most important central sites involved in the modulation and integration of the CSAR. Angiotensin II, AT1 receptors and NAD(P)H oxidase-derived superoxide anions pathway in the PVN are mainly responsible for the enhanced CSAR in CHF and hypertension. Central angiotensin-(1-7), nitric oxide, endothelin, intermedin, hydrogen peroxide and several other signal molecules are involved in regulating CSAR. Blockade of the CSAR shows beneficial effects in CHF and hypertension. This review focuses on the anatomical and physiological basis of the CSAR, the interaction of CSAR with baroreflex and chemoreflex, and the role of enhanced CSAR in the pathogenesis of CHF and hypertension.
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Affiliation(s)
- W.-W. Chen
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
| | - X.-Q. Xiong
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
| | - Q. Chen
- Department of Pathophysiology; Nanjing Medical University; Nanjing Jiangsu China
| | - Y.-H. Li
- Department of Pathophysiology; Nanjing Medical University; Nanjing Jiangsu China
| | - Y.-M. Kang
- Department of Physiology and Pathophysiology; Cardiovascular Research Center; Xi'an Jiaotong University School of Medicine; Xi'an China
| | - G.-Q. Zhu
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
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12
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Haack KKV, Zucker IH. Central mechanisms for exercise training-induced reduction in sympatho-excitation in chronic heart failure. Auton Neurosci 2014; 188:44-50. [PMID: 25458427 DOI: 10.1016/j.autneu.2014.10.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 08/19/2014] [Accepted: 10/13/2014] [Indexed: 11/17/2022]
Abstract
The control of sympathetic outflow in the chronic heart failure (CHF) state is markedly abnormal. Patients with heart failure present with increased plasma norepinephrine and increased sympathetic nerve activity. The mechanism for this sympatho-excitation is multiple and varied. Both depression in negative feedback sensory control mechanisms and augmentation of excitatory reflexes contribute to this sympatho-excitation. These include the arterial baroreflex, cardiac reflexes, arterial chemoreflexes and cardiac sympathetic afferent reflexes. In addition, abnormalities in central signaling in autonomic pathways have been implicated in the sympatho-excitatory process in CHF. These mechanisms include increases in central Angiotensin II and the Type 1 receptor, increased in reactive oxygen stress, upregulation in glutamate signaling and NR1 (N-methyl-D-aspartate subtype 1) receptors and others. Exercise training in the CHF state has been shown to reduce sympathetic outflow and result in increased survival and reduced cardiac events. Exercise training has been shown to reduce central Angiotensin II signaling including the Type 1 receptor and reduce oxidative stress by lowering the expression of many of the subunits of NADPH oxidase. In addition, there are profound effects on the central generation of nitric oxide and nitric oxide synthase in sympatho-regulatory areas of the brain. Recent studies have pointed to the balance between Angiotensin Converting Enzyme (ACE) and ACE2, translating into Angiotensin II and Angiotensin 1-7 as important regulators of sympathetic outflow. These enzymes appear to be normalized following exercise training in CHF. Understanding the precise molecular mechanisms by which exercise training is sympatho-inhibitory will uncover new targets for therapy.
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Affiliation(s)
- Karla K V Haack
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, United States
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, United States.
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13
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Xiong XQ, Chen WW, Zhu GQ. Adipose afferent reflex: sympathetic activation and obesity hypertension. Acta Physiol (Oxf) 2014; 210:468-78. [PMID: 24118791 DOI: 10.1111/apha.12182] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/05/2013] [Accepted: 10/09/2013] [Indexed: 01/09/2023]
Abstract
Excessive sympathetic activity contributes to the pathogenesis of hypertension and the progression of the related organ damage. Adipose afferent reflex (AAR) is a sympatho-excitatory reflex that the afferent activity from white adipose tissue (WAT) increases sympathetic outflow and blood pressure. Hypothalamic paraventricular nucleus (PVN or PVH) is one of the central sites in the control of the AAR, and ionotropic glutamate receptors in the nucleus mediate the AAR. The AAR is enhanced in obesity and obesity hypertension. Enhanced WAT afferent activity and AAR contribute to the excessive sympathetic activation and hypertension in obesity. Blockage of the AAR attenuates the excessive sympathetic activity and hypertension. Leptin may be one of sensors in the WAT for the AAR, and is involved in the enhanced AAR in obesity and hypertension. This review focuses on the neuroanatomical basis and physiological functions of the AAR, and the important role of the enhanced AAR in the pathogenesis of obesity hypertension.
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Affiliation(s)
- X.-Q. Xiong
- Key Laboratory of Cardiovascular Disease and Molecular Intervention; Department of Physiology; Nanjing Medical University; Nanjing 210029 China
| | - W.-W. Chen
- Key Laboratory of Cardiovascular Disease and Molecular Intervention; Department of Physiology; Nanjing Medical University; Nanjing 210029 China
| | - G.-Q. Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention; Department of Physiology; Nanjing Medical University; Nanjing 210029 China
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Edgell H, Stickland MK. Activation of the carotid chemoreflex secondary to muscle metaboreflex stimulation in men. Am J Physiol Regul Integr Comp Physiol 2014; 306:R693-700. [PMID: 24573180 DOI: 10.1152/ajpregu.00472.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent work has shown that the carotid chemoreceptor (CC) contributes to sympathetic control of cardiovascular function during exercise, despite no evidence of increased circulating CC stimuli, suggesting enhanced CC activity/sensitivity. As interactions between metaboreceptors and chemoreceptors have been previously observed, the purpose of this study was to isolate the metaboreflex while acutely stimulating or inhibiting the CC to determine whether the metaboreflex increased CC activity/sensitivity. Fourteen young healthy men (height: 177.0 ± 2.1 cm, weight: 85.8 ± 5.5 kg, age: 24.6 ± 1.1 yr) performed three trials of 40% maximal voluntary contraction handgrip for 2 min, followed by 3 min of postexercise circulatory occlusion (PECO) to stimulate the metaboreflex. In random order, subjects either breathed room air, hypoxia (target SPo2 = 85%), or hyperoxia (FiO2 = 1.0) during the PECO to modulate the chemoreflex. After these trials, a resting hypoxia trial was conducted without handgrip or PECO. Ventilation (Ve), heart rate (HR), blood pressure, and muscle sympathetic nervous activity (MSNA) data were continuously obtained. Relative to normoxic PECO, inhibition of the CC during hyperoxic PECO resulted in lower MSNA (P = 0.038) and HR (P = 0.021). Relative to normoxic PECO, stimulation of the CC during hypoxic PECO resulted in higher HR (P < 0.001) and Ve (P < 0.001). The ventilatory and MSNA responses to hypoxic PECO were not greater than the sum of the responses to hypoxia and PECO individually, indicating that the CC are not sensitized during metaboreflex activation. These results demonstrate that stimulation of the metaboreflex activates, but does not sensitize the CC, and help explain the enhanced CC activity with exercise.
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Affiliation(s)
- H Edgell
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
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Li P, Sun HJ, Zhang LL, Ding L, Han Y, Zhu GQ, Zhou YB. Melanocortin 4 receptors in the paraventricular nucleus modulate the adipose afferent reflex in rat. PLoS One 2013; 8:e80295. [PMID: 24244673 PMCID: PMC3823614 DOI: 10.1371/journal.pone.0080295] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/01/2013] [Indexed: 11/26/2022] Open
Abstract
Background and Aim Paraventricular nucleus (PVN) of hypothalamus is an important central component in modulating adipose afferent reflex (AAR). Melanocortin receptors (MC3/4Rs) expressions are found in the hypothalamic PVN. This study was designed to determine the roles of MC3/4Rs in the PVN in modulating the AAR and its downstream signaling pathway in normal rats. Methodology/Principal Findings Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in anaesthetized rats. AAR was evaluated using RSNA and MAP responses to capsaicin injection into the inguinal white adipose tissue (iWAT). Microinjection of the MC3/4R agonist melanotan II (MTII) into the PVN enhanced the AAR. The MC3/4R antagonist SHU9119 or MC4R antagonist HS024 attenuated the AAR and abolished MTII-induced AAR response. The adenylate cyclase (AC) inhibitor SQ22536 or the protein kinase A (PKA) inhibitor Rp-cAMP attenuated the AAR and the effect of MTII on the AAR was abolished by pretreatment with SQ22536 or Rp-cAMP in the PVN. Furthermore, both PVN microinjection of MTII and iWAT injection of capsaicin increased the cAMP level in the PVN. SHU9119 in the PVN abolished the increase in cAMP level which induced by iWAT injection of capsaicin. Conclusion The activation of MC4Rs rather than MC3Rs enhances the AAR, and a cAMP-PKA pathway is involved in the effects of MC4Rs in the PVN.
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Affiliation(s)
- Peng Li
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
- Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hai-Jian Sun
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Ling-Li Zhang
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Lei Ding
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Ying Han
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Guo-Qing Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Ye-Bo Zhou
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, China
- * E-mail:
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Wang Y, Seto SW, Golledge J. Angiotensin II, sympathetic nerve activity and chronic heart failure. Heart Fail Rev 2012; 19:187-98. [DOI: 10.1007/s10741-012-9368-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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17
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Ciriello J, Moreau JM. Leptin signaling in the nucleus of the solitary tract alters the cardiovascular responses to activation of the chemoreceptor reflex. Am J Physiol Regul Integr Comp Physiol 2012; 303:R727-36. [PMID: 22914750 DOI: 10.1152/ajpregu.00068.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Circulating levels of leptin are elevated in individuals suffering from chronic intermittent hypoxia (CIH). Systemic and central administration of leptin elicits increases in sympathetic nervous activity (SNA), arterial pressure (AP), and heart rate (HR), and it attenuates the baroreceptor reflex, cardiovascular responses that are similar to those observed during CIH as a result of activation of chemoreceptors by the systemic hypoxia. Therefore, experiments were done in anesthetized Wistar rats to investigate the effects of leptin in nucleus of the solitary tract (NTS) on AP and HR responses, and renal SNA (RSNA) responses during activation of NTS neurons and the chemoreceptor reflex. Microinjection of leptin (5-100 ng; 20 nl) into caudal NTS pressor sites (l-glutamate; l-Glu; 0.25 M; 10 nl) elicited dose-related increases in AP, HR, and RSNA. Leptin microinjections (5 ng; 20 nl) into these sites potentiated the increase in AP and HR elicited by l-Glu. Additionally, bilateral injections of leptin (5 ng; 100 nl) into NTS potentiated the increase in AP and attenuated the bradycardia to systemic activation of the chemoreflex. In the Zucker obese rat, leptin injections into NTS neither elicited cardiovascular responses nor altered the cardiovascular responses to activation of the chemoreflex. Taken together, these data indicate that leptin exerts a modulatory effect on neuronal circuits within NTS that control cardiovascular responses elicited during the reflex activation of arterial chemoreceptors and suggest that increased AP and SNA observed in individuals with CIH may be due, in part, by leptin's effects on the chemoreflex at the level of NTS.
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Affiliation(s)
- John Ciriello
- Dept. of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Univ. of Western Ontario, London, ON, Canada.
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Shi Z, Chen WW, Xiong XQ, Han Y, Zhou YB, Zhang F, Gao XY, Zhu GQ. Sympathetic activation by chemical stimulation of white adipose tissues in rats. J Appl Physiol (1985) 2012; 112:1008-14. [PMID: 22223453 DOI: 10.1152/japplphysiol.01164.2011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Injection of leptin into white adipose tissue (WAT) increases sympathetic outflow. The present study was designed to determine the effects of capsaicin and other chemicals in WAT on the sympathetic outflow and blood pressure and the roles of WAT afferents and hypothalamic paraventricular nucleus (PVN) in the adipose afferent reflex (AAR). The AAR was induced by injection of capsaicin, bradykinin, adenosine, adenosine triphosphate (ATP), or leptin into inguinal WAT (iWAT) or retroperitoneal WAT (rWAT) in anesthetized rats. The iWAT injection of capsaicin increased the renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) but not the heart rate. Bradykinin, adenosine, or leptin but not ATP in the iWAT caused similar effects to capsaicin on the RSNA and MAP. Intravenous, intramuscular, or intradermal injection of capsaicin had no significant effects on the RSNA and MAP. The effects of capsaicin in rWAT were similar to that in iWAT on the RSNA and MAP. Furthermore, injection of capsaicin into the iWAT increased the WAT afferent nerve activities, WAT efferent nerve activity, and brown adipose tissue efferent nerve activity. The iWAT denervation or chemical lesion of the PVN neurons with kainic acid abolished the AAR induced by the iWAT injection of capsaicin. These results indicate that the stimulation of iWAT afferents with capsaicin, bradykinin, adenosine, or leptin reflexly increases the RSNA and blood pressure. The iWAT afferents and the PVN are involved in the AAR induced by capsaicin in the iWAT.
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Affiliation(s)
- Zhen Shi
- Department of Physiology, Nanjing Medical Univ., Nanjing, Jiangsu 210029, China
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Gan XB, Duan YC, Xiong XQ, Li P, Cui BP, Gao XY, Zhu GQ. Inhibition of cardiac sympathetic afferent reflex and sympathetic activity by baroreceptor and vagal afferent inputs in chronic heart failure. PLoS One 2011; 6:e25784. [PMID: 21991351 PMCID: PMC3185007 DOI: 10.1371/journal.pone.0025784] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 09/09/2011] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac sympathetic afferent reflex (CSAR) contributes to sympathetic activation and angiotensin II (Ang II) in paraventricular nucleus (PVN) augments the CSAR in vagotomized (VT) and baroreceptor denervated (BD) rats with chronic heart failure (CHF). This study was designed to determine whether it is true in intact (INT) rats with CHF and to determine the effects of cardiac and baroreceptor afferents on the CSAR and sympathetic activity in CHF. Methodology/Principal Findings Sham-operated (Sham) or coronary ligation-induced CHF rats were respectively subjected to BD+VT, VT, cardiac sympathetic denervation (CSD) or INT. Under anesthesia, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded, and the CSAR was evaluated by the RSNA and MAP responses to epicardial application of capsaicin. Either CSAR or the responses of RSNA, MAP and CSAR to Ang II in PVN were enhanced in CHF rats treated with BD+VT, VT or INT. Treatment with VT or BD+VT potentiated the CSAR and the CSAR responses to Ang II in both Sham and CHF rats. Treatment with CSD reversed the capsaicin-induced RSNA and MAP changes and the CSAR responses to Ang II in both Sham and CHF rats, and reduced the RSNA and MAP responses to Ang II only in CHF rats. Conclusions The CSAR and the CSAR responses to Ang II in PVN are enhanced in intact CHF rats. Baroreceptor and vagal afferent activities inhibit CSAR and the CSAR responses to Ang II in intact Sham and CHF rats.
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Affiliation(s)
- Xian-Bing Gan
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
| | - Yang-Can Duan
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Department of Medical Ultrasound, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xiao-Qing Xiong
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
| | - Peng Li
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Bai-Ping Cui
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Xing-Ya Gao
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Guo-Qing Zhu
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
- * E-mail:
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Yi X, Zimmerman MC, Yang R, Tong J, Vinogradov S, Kabanov AV. Pluronic-modified superoxide dismutase 1 attenuates angiotensin II-induced increase in intracellular superoxide in neurons. Free Radic Biol Med 2010; 49:548-58. [PMID: 20493251 PMCID: PMC2998907 DOI: 10.1016/j.freeradbiomed.2010.04.039] [Citation(s) in RCA: 48] [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: 07/20/2009] [Revised: 04/29/2010] [Accepted: 04/30/2010] [Indexed: 11/21/2022]
Abstract
Overexpressing superoxide dismutase 1 (SOD1; also called Cu/ZnSOD), an intracellular superoxide (O(2)(*-))-scavenging enzyme, in central neurons inhibits angiotensin II (AngII) intraneuronal signaling and normalizes cardiovascular dysfunction in diseases associated with enhanced AngII signaling in the brain, including hypertension and heart failure. However, the blood-brain barrier and neuronal cell membranes impose a tremendous impediment for the delivery of SOD1 to central neurons, which hinders the potential therapeutic impact of SOD1 treatment on these diseases. To address this, we developed conjugates of SOD1 with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Pluronic) (SOD1-P85 and SOD1-L81), which retained significant SOD1 enzymatic activity. The modified SOD1 effectively scavenged xanthine oxidase/hypoxanthine-derived O(2)(*-), as determined by HPLC and the measurement of 2-hydroxyethidium. Using catecholaminergic neurons, we observed an increase in neuronal uptake of SOD1-Pluronic after 1, 6, or 24h, compared to neurons treated with pure SOD1 or PEG-SOD1. Importantly, without inducing neuronal toxicity, SOD1-Pluronic conjugates significantly inhibited AngII-induced increases in intraneuronal O(2)(*-) levels. These data indicate that SOD1-Pluronic conjugates penetrate neuronal cell membranes, which results in elevated intracellular levels of functional SOD1. Pluronic conjugation may be a new delivery system for SOD1 into central neurons and therapeutically beneficial for AngII-related cardiovascular diseases.
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Affiliation(s)
- Xiang Yi
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-5830
| | - Matthew C. Zimmerman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5830
| | - Ruifang Yang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5830
| | - Jing Tong
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-5830
| | - Serguei Vinogradov
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-5830
| | - Alexander V. Kabanov
- Department of Pharmaceutical Sciences and Center for Drug Delivery and Nanomedicine, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-5830
- Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119899 Moscow, Russia
- Correspondence: Alexander V. Kabanov, Center for Drug Delivery and Nanomedicine, 985830 Nebraska Medical Center, Omaha, NE 68198-5830; Tel: (402) 559-9364; Fax (402) 559-9365,
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Lykidis CK, Kumar P, Vianna LC, White MJ, Balanos GM. A respiratory response to the activation of the muscle metaboreflex during concurrent hypercapnia in man. Exp Physiol 2009; 95:194-201. [DOI: 10.1113/expphysiol.2009.049999] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Pulgar VM, Hong JKS, Jessup JA, Massmann AG, Diz DI, Figueroa JP. Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep. Am J Physiol Regul Integr Comp Physiol 2009; 297:R446-52. [PMID: 19515988 DOI: 10.1152/ajpregu.00023.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The effects of chronic mild hypoxemia on the binding of angiotensin receptors in selected brain stem nuclei and reflex responses were studied in fetal sheep. Fetal and maternal catheters were placed at 120 days' gestation, and animals received intratracheal maternal administration of nitrogen (n = 16) or compressed air in controls (n = 19). Nitrogen infusion was adjusted to reduce fetal brachial artery PO(2) by 25% during 5 days. Spontaneous baroreflex sensitivity and spectral analysis of the pulse interval were analyzed during the 5 days hypoxemia period using 90 min of daily recording. Brains of control and hypoxemic animals were collected, and brain stem angiotensin receptor binding was studied by in vitro autoradiography at 130 days of gestation. After 5 days of hypoxemia, some animals in each group were submitted to one complete umbilical cord occlusion during 5 min. [(125)I]sarthran binding showed that chronic mild hypoxemia significantly increases angiotensin type 1 receptor, angiotensin type 2 receptor, and ANG-(1-7) angiotensin receptor binding sites in the nucleus tractus solitarius and dorsal motor nucleus of the vagus (P < 0.05). Hypoxemia induced lower baroreflex sensitivity and a higher low frequency-to-high frequency ratio in the fetus, consistent with a shift from vagal to sympathetic autonomic cardiac regulation. Cord occlusion to elicit a chemoreflex response induced a greater bradycardic response in hypoxemic fetuses (slope of the initial fall in heart rate; 11.3 +/- 1.9 vs. 6.4 +/- 1.2 beats x min(-1) x s(-1), P < 0.05). In summary, chronic mild hypoxemia increased binding of angiotensin receptors in brain stem nuclei, decreased spontaneous baroreflex gain, and increased chemoreflex responses to asphyxia in the fetus. These results suggest hypoxemia-induced alterations in brain stem mechanisms for cardiovascular control.
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Affiliation(s)
- Victor M Pulgar
- Dept. of Obstetrics and Gynecology, Wake Forest Univ. School of Medicine, Winston Salem, NC 27157, USA.
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Meyer C, Rana OR, Saygili E, Ozüyaman B, Latz K, Rassaf T, Kelm M, Schauerte P. Hyperoxic chemoreflex sensitivity is impaired in patients with neurocardiogenic syncope. Int J Cardiol 2009; 142:38-43. [PMID: 19176256 DOI: 10.1016/j.ijcard.2008.12.081] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 09/19/2008] [Accepted: 12/12/2008] [Indexed: 11/16/2022]
Abstract
BACKGROUND During the development of neurocardiogenic syncope (NCS) postural dependant venous blood pooling sets off a cascade of autonomic reflexes. This causes an initial rise in sympathetic tone, which is followed by an overshoot parasympathetic activation resulting in systemic vasodilatation and/or sinus bradycardia. However, other factors like associated hyperventilation or changes in blood gas content may also contribute to syncope. Hyperoxic cardiac chemoreflex sensitivity (CHRS) is an autonomic functional test that describes the heart rate decrease in response to increases in blood oxygen content. The purpose of this study was to investigate whether CHRS is altered in NCS. METHODS AND RESULTS CHRS was compared in 16 NCS patients (49+/-4 yr old) vs. 16 age and gender matched controls (53+/-2 yr old). NCS was verified by clinical syncope and positive head-up tilt testing. The hyperoxic CHRS was measured by determination of the venous partial pressure of oxygen and heart rate before and after 5 min of pure oxygen inhalation. The difference of the R-R intervals before and after oxygen inhalation divided by the difference in the oxygen pressures were calculated as hyperoxic chemoreflex sensitivity [ms/mm Hg]. CHRS in the control group was 7.1+/-1.1 ms/mm Hg. By contrast, CHRS in NCS patients was significantly lower (2.8+/-1.0 ms/mm Hg; p<0.05). CONCLUSION Neurocardiogenic syncope is associated with decreased hyperoxic cardiac chemoreflex sensitivity possibly reflecting impaired deactivation of arterial chemoreceptors. The clinical and pathophysiologic importance of chemosensor function in neurocardiogenic syncope needs to be investigated in more detail.
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Affiliation(s)
- Christian Meyer
- Division of Cardiology, Pulmonology and Vascular Medicine, University of Aachen, Germany.
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Quagliotto E, Neckel H, Riveiro DF, Casali KR, Mostarda C, Irigoyen MC, Dall'ago P, Rasia-Filho AA. Histamine in the posterodorsal medial amygdala modulates cardiovascular reflex responses in awake rats. Neuroscience 2008; 157:709-19. [PMID: 18955117 DOI: 10.1016/j.neuroscience.2008.09.053] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 09/03/2008] [Accepted: 09/29/2008] [Indexed: 11/18/2022]
Abstract
Centrally injected histamine (HA) affects heart rate (HR), arterial blood pressure (BP), and sympathetic activity in rats. The posterodorsal medial amygdala (MePD) has high levels of histidine decarboxylase, connections with brain areas involved with the modulation of cardiovascular responses, and is relevant for the pathogenesis of hypertension. However, there is no report demonstrating the role of the MePD histaminergic activity on the cardiovascular function in awake rats. The aims of the present work were: 1) to study the effects of two doses (10-100 nM) of HA microinjected in the MePD on basal cardiovascular recordings and on baroreflex- and chemoreflex-mediated responses; 2) to reveal whether cardiovascular reflex responses could be affected by MePD microinjections of (R)-alpha-methylhistamine (AH3), an agonist of the inhibitory autoreceptor H3; and, 3) to carry out a power spectral analysis to evaluate the contribution of the sympathetic and parasympathetic components in the variability of the HR and BP recordings. When compared with the control group (microinjected with saline, 0.3 microl), HA (10 nM) promoted an increase in the MAP50, i.e. the mean value of BP at half of the HR range evoked by the baroreflex response. Histamine (100 nM) did not affect the baroreflex activity, but significantly decreased the parasympathetic component of the HR variability, increased the sympathetic/parasympathetic balance at basal conditions (these two latter evaluated by the power spectral analysis), and promoted an impairment in the chemoreflex bradycardic response. Microinjection of AH3 (10 microM) led to mixed results, which resembled the effects of both doses of HA employed here. Present data suggest that cardiovascular changes induced by baroreceptors and chemoreceptors involve the histaminergic activity in the MePD. This neural regulation of reflex cardiovascular responses can have important implications for homeostatic and allostatic conditions and possibly for the behavioral displays modulated by the rat MePD.
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Affiliation(s)
- E Quagliotto
- Department of Physiological Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre, R. Sarmento Leite 245, Porto Alegre 90170-050 RS, Brazil
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Wang WZ, Gao L, Wang HJ, Zucker IH, Wang W. Interaction between cardiac sympathetic afferent reflex and chemoreflex is mediated by the NTS AT1 receptors in heart failure. Am J Physiol Heart Circ Physiol 2008; 295:H1216-H1226. [PMID: 18660444 DOI: 10.1152/ajpheart.00557.2008] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Several sympathoexcitatory reflexes, such as the cardiac sympathetic afferent reflex (CSAR) and arterial chemoreflex, are significantly augmented and contribute to elevated sympathetic outflow in chronic heart failure (CHF). This study was undertaken to investigate the interaction between the CSAR and the chemoreflex in CHF and to further identify the involvement of angiotensin II type 1 receptors (AT1Rs) in the nucleus of the tractus solitarius (NTS) in this interaction. CHF was induced in rats by coronary ligation. Acute experiments were performed in anesthetized rats. The chemoreflex-induced increase in cardiovascular responses was significantly greater in CHF than in sham-operated rats after either chemical or electrical activation of the CSAR. The inhibition of the CSAR by epicardial lidocaine reduced the chemoreflex-induced effects in CHF rats but not in sham-operated rats. Bilateral NTS injection of the AT1R antagonist losartan (10 and 100 pmol) dose-dependently decreased basal sympathetic nerve activity in CHF but not in sham-operated rats. This procedure also abolished the CSAR-induced enhancement of the chemoreflex. The discharge and chemosensitivity of NTS chemosensitive neurons were significantly increased following the stimulation of the CSAR in sham-operated and CHF rats, whereas CSAR inhibition by epicardial lidocaine significantly attenuated chemosensitivity of NTS neurons in CHF but not in sham-operated rats. Finally, the protein expression of AT1R in the NTS was significantly higher in CHF than in sham-operated rats. These results demonstrate that the enhanced cardiac sympathetic afferent input contributes to an excitatory effect of chemoreflex function in CHF, which is mediated by an NTS-AT1R-dependent mechanism.
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Affiliation(s)
- Wei-Zhong Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Ctr., 985850 Nebraska Medical Ctr., Omaha, NE 68198-5850, USA.
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Stickland MK, Miller JD. The best medicine: exercise training normalizes chemosensitivity and sympathoexcitation in heart failure. J Appl Physiol (1985) 2008; 105:779-81. [PMID: 18635872 DOI: 10.1152/japplphysiol.90889.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Michael K Stickland
- Dept. of Medicine, Health Sciences Centre, Univ. of Alberta, Edmonton, Alberta, Canada T6G 2B7.
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Li YL, Ding Y, Agnew C, Schultz HD. Exercise training improves peripheral chemoreflex function in heart failure rabbits. J Appl Physiol (1985) 2008; 105:782-90. [PMID: 18583379 DOI: 10.1152/japplphysiol.90533.2008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
An enhancement of peripheral chemoreflex sensitivity contributes to sympathetic hyperactivity in chronic heart failure (CHF) rabbits. The enhanced chemoreflex function in CHF involves augmented carotid body (CB) chemoreceptor activity via upregulation of the angiotensin II (ANG II) type 1 (AT(1))-receptor pathway and downregulation of the neuronal nitric oxide synthase (nNOS)-nitric oxide (NO) pathway in the CB. Here we investigated whether exercise training (EXT) normalizes the enhanced peripheral chemoreflex function in CHF rabbits and possible mechanisms mediating this effect. EXT partially, but not fully, normalized the exaggerated baseline renal sympathetic nerve activity (RSNA) and the response of RSNA to hypoxia in CHF rabbits. EXT also decreased the baseline CB nerve single-fiber discharge (4.9 +/- 0.4 vs. 7.7 +/- 0.4 imp/s at Po(2) = 103 +/- 2.3 Torr) and the response to hypoxia (20.6 +/- 1.1 vs. 36.3 +/- 1.3 imp/s at Po(2) = 41 +/- 2.2 Torr) from CB chemoreceptors in CHF rabbits, which could be reversed by treatment of the CB with ANG II or a nNOS inhibitor. Our results also showed that NO concentration and protein expression of nNOS were increased in the CBs from EXT + CHF rabbits, compared with that in CHF rabbits. On the other hand, elevated ANG II concentration and AT(1)-receptor overexpression of the CBs in CHF state were blunted by EXT. These results indicate that EXT normalizes the CB chemoreflex in CHF by preventing an increase in afferent CB chemoreceptor activity. EXT reverses the alterations in the nNOS-NO and ANG II-AT(1)-receptor pathways in the CB responsible for chemoreceptor sensitization in CHF.
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Affiliation(s)
- Yu-Long Li
- Dept. of Cellular and Integrative Physiology, Univ. of Nebraska Medical Center, Omaha, NE 68198, USA
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Ding Y, Li YL, Schultz HD. Downregulation of carbon monoxide as well as nitric oxide contributes to peripheral chemoreflex hypersensitivity in heart failure rabbits. J Appl Physiol (1985) 2008; 105:14-23. [PMID: 18356479 DOI: 10.1152/japplphysiol.01345.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peripheral chemoreflex sensitivity is potentiated in clinical and experimental chronic heart failure (CHF). Downregulation of nitric oxide (NO) synthase (NOS) in the carotid body (CB) is involved in this effect. However, it remains poorly understood whether carbon monoxide (CO) also contributes to the altered peripheral chemoreflex sensitivity in CHF. This work highlights the effect of NO and CO on renal sympathetic nerve activity (RSNA) in response to graded hypoxia in conscious rabbits. Renal sympathetic nerve responses to graded hypoxia were enhanced in CHF rabbits compared with sham rabbits. The NO donor S-nitroso-N-acetylpenicillamine (SNAP, 1.2 microg x kg(-1) x min(-1)) and the CO-releasing molecule tricarbonyldichlororuthenium (II) dimer {[Ru(CO)(3)Cl(2)](2), 3.0 microg x kg(-1) x min(-1)} each attenuated hypoxia-induced RSNA increases in CHF rabbits (P < 0.05), but the degree of attenuation of RSNA induced by SNAP or [Ru(CO)(3)Cl(2)](2) was smaller than that induced by SNAP + [Ru(CO)(3)Cl(2)](2). Conversely, treatment with the NOS inhibitor N(omega)-nitro-L-arginine (30 mg/kg) + the heme oxygenase (HO) inhibitor Cr (III) mesoporphyrin IX chloride (0.5 mg/kg) augmented the renal sympathetic nerve response to hypoxia in sham rabbits to a greater extent than treatment with either inhibitor alone and was without effect in CHF rabbits. In addition, using immunostaining and Western blot analyses, we found that expression of neuronal NOS, endothelial NOS, and HO-2 protein (expressed as the ratio of NOS or HO-2 expression to beta-tubulin protein expression) was lower in CBs from CHF (0.19 +/- 0.04, 0.17 +/- 0.06, and 0.15 +/- 0.02, respectively) than sham (0.63 +/- 0.04, 0.56 +/- 0.06, and 0.27 +/- 0.03, respectively) rabbits (P < 0.05). These results suggest that a deficiency of NO and CO in the CBs augments peripheral chemoreflex sensitivity to hypoxia in CHF.
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Affiliation(s)
- Yanfeng Ding
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
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Wang WZ, Wang LG, Gao L, Wang W. Contribution of AMPA/kainate receptors in the rostral ventrolateral medulla to the hypotensive and sympathoinhibitory effects of clonidine. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1232-8. [PMID: 17581836 DOI: 10.1152/ajpregu.00233.2007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The depressor and sympathoinhibitory effect of the imidazoline drug clonidine is reported to be associated with functional states of the central glutamate receptors. The rostral ventrolateral medulla (RVLM) has been recognized as a specific target area for mediating the central depressor mechanism of clonidine. The objective of this study was to determine the role of the glutamate receptor subtype α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor within the RVLM in clonidine-induced depressor and sympathoinhibitory action in anesthetized normotensive rats. Unilateral microinjection of 200 pmol of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a potent AMPA/kainate receptor antagonist, into the RVLM completely abolished the pressor action evoked by AMPA (5 pmol) without affecting the pressor action of N-methyl-d-aspartate (20 pmol). Pretreatment with intra-RVLM injection of CNQX (20 and 200 pmol) dose dependently attenuated the reduction in blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) elicited by intra-RVLM clonidine (5 nmol) or intravenous clonidine (10 μg/kg), while 2 pmol of CNQX did not alter clonidine-induced cardiovascular action. Furthermore, the decreases in BP, HR, and RSNA evoked by intravenous clonidine (10 μg/kg) or intra-RVLM clonidine (5 nmol) were reversed when CNQX (20 and 200 pmol) was subsequently injected into the RVLM. In conclusion, these data show that blockade of AMPA/kainate receptors in the RVLM significantly antagonizes decreases in BP, HR, and sympathetic activity induced by clonidine, suggesting that the AMPA/kainate receptors within the RVLM contribute to the depressor and sympathoinhibitory effect of clonidine.
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Affiliation(s)
- Wei-Zhong Wang
- Department of Physiology, Second Military Medical University, 800 Xiang-Yin Road, Shanghai 200433, China.
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Schultz HD, Li YL. Carotid body function in heart failure. Respir Physiol Neurobiol 2007; 157:171-85. [PMID: 17374517 PMCID: PMC1965591 DOI: 10.1016/j.resp.2007.02.011] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 02/07/2007] [Accepted: 02/08/2007] [Indexed: 11/16/2022]
Abstract
In this review, we summarize the present state of knowledge of the functional characteristics of the carotid body (CB) chemoreflex with respect to control of sympathetic nerve activity (SNA) in chronic heart failure (CHF). Evidence from both CHF patients and animal models of CHF has clearly established that the CB chemoreflex is enhanced in CHF and contributes to the tonic elevation in SNA. This adaptive change derives from altered function at the level of both the afferent and central nervous system (CNS) pathways of the reflex arc. At the level of the CB, an elevation in basal afferent discharge occurs under normoxic conditions in CHF rabbits, and the discharge responsiveness to hypoxia is enhanced. Outward voltage-gated K(+) currents (I(K)) are suppressed in CB glomus cells from CHF rabbits, and their sensitivity to hypoxic inhibition is enhanced. These changes in I(K) derive partly from downregulation of nitric oxide synthase (NOS)/NO signaling and upregulation of angiotensin II (Ang II)/Ang II receptor (AT(1)R) signaling in glomus cells. At the level of the CNS, interactions of the enhanced input from CB chemoreceptors with altered input from baroreceptor and cardiac afferent pathways and from central Ang II further enhance sympathetic drive. In addition, impaired function of NO in the paraventricular nucleus of the hypothalamus participates in the increased SNA response to CB chemoreceptor activation. These results underscore the principle that multiple mechanisms involving Ang II and NO at the level of both the CB and CNS represent complementary and perhaps redundant adaptive mechanisms to enhance CB chemoreflex function in CHF.
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Affiliation(s)
- Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska College of Medicine, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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Stickland MK, Miller JD, Smith CA, Dempsey JA. Carotid chemoreceptor modulation of regional blood flow distribution during exercise in health and chronic heart failure. Circ Res 2007; 100:1371-8. [PMID: 17431189 DOI: 10.1161/01.res.0000266974.84590.d2] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous work has shown sensitization of carotid chemoreceptor (CC) responsiveness during exercise as well as in chronic heart failure (CHF). Accordingly, we hypothesized that the CCs contribute to the sympathetic restraint of skeletal muscle blood flow during exercise and CHF. We examined the effect of transient CC inhibition on total (Con(T)) and hindlimb (Con(L)) conductance, and blood pressure at rest and during exercise (2.5 miles per hour, 5% grade) in chronically instrumented dogs. Via a carotid arterial catheter, CCs were inhibited using dopamine (5 to 10 microg/kg) or hyperoxic lactated Ringer's solution. Although vasodilation did not occur with CC inhibition in resting healthy dogs, CC inhibition during exercise caused an immediate vasodilatory response (increase in Con(T) and Con(L) and decrease in blood pressure). When comparing the peak Con(L) response from CC inhibition versus alpha-adrenergic blockade (phentolamine), we found that the CCs accounted for approximately one-third of the total sympathetic restraint during exercise. CHF was then induced by chronic rapid cardiac pacing and characterized by impaired cardiac function, enhanced chemosensitivity, and greater sympathetic restraint at rest and during exercise. In contrast to healthy dogs, CC inhibition in resting CHF dogs produced vasodilation, whereas a similar vasodilatory response was observed during exercise in CHF as compared with healthy dogs. The vasodilation following CC inhibition during exercise and in CHF was abolished with alpha-adrenergic blockade and was absent in healthy exercising animals after carotid body denervation. These results establish an important role for the CCs in cardiovascular control in the healthy animal during exercise and in the CHF animal both at rest and during exercise.
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Affiliation(s)
- Michael K Stickland
- John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin, Madison, WI, USA.
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Du YH, Chen AF. A “love triangle” elicited by electrochemistry: complex interactions among cardiac sympathetic afferent, chemo-, and baroreflexes. J Appl Physiol (1985) 2007; 102:9-10. [PMID: 16990500 DOI: 10.1152/japplphysiol.01032.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Wang WZ, Gao L, Pan YX, Zucker IH, Wang W. Differential effects of cardiac sympathetic afferent stimulation on neurons in the nucleus tractus solitarius. Neurosci Lett 2006; 409:146-50. [PMID: 17014954 PMCID: PMC1904510 DOI: 10.1016/j.neulet.2006.09.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 09/12/2006] [Accepted: 09/14/2006] [Indexed: 02/06/2023]
Abstract
Activation of the cardiac "sympathetic afferent" reflex (CSAR) has been reported to depress the arterial baroreflex and enhance the arterial chemoreflex via a central mechanism. In the present study, we used single-unit extracellular recording techniques to examine the effects of stimulation of cardiac sympathetic afferents on baro- or chemosensitive neurons in the nucleus tractus solitarius (NTS) in anesthetized rats. Of 54 barosensitive NTS neurons tested for their response to epicardial application of capsaicin (0.4 microg), 38 were significantly (P<0.01) inhibited by 38% while 16 did not respond. Of 42 NTS chemosensitive neurons tested for their response to capsaicin, 33 were significantly (P<0.01) excited by 47% while 9 did not respond. In addition, of 12 both barosensitive and chemosensitive NTS neurons tested for capsaicin, 2 were excited, 7 were inhibited, and 3 did not respond. In conclusion, this study indicates that CSAR activation inhibited NTS barosensitive neurons and excited NTS chemosensitive neurons, suggesting that the NTS plays an important role in processing the interactions between these cardiovascular reflexes.
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Affiliation(s)
- Wei-Zhong Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
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