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Zhang D, Tu H, Wang C, Cao L, Muelleman RL, Wadman MC, Li YL. Correlation of Ventricular Arrhythmogenesis with Neuronal Remodeling of Cardiac Postganglionic Parasympathetic Neurons in the Late Stage of Heart Failure after Myocardial Infarction. Front Neurosci 2017; 11:252. [PMID: 28533740 PMCID: PMC5420597 DOI: 10.3389/fnins.2017.00252] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 04/20/2017] [Indexed: 01/06/2023] Open
Abstract
Introduction: Ventricular arrhythmia is a major cause of sudden cardiac death in patients with chronic heart failure (CHF). Our recent study demonstrates that N-type Ca2+ currents in intracardiac ganglionic neurons are reduced in the late stage of CHF rats. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Only AVG nerve terminals innervate the ventricular myocardium. In this study, we tested the correlation of electrical remodeling in AVG neurons with ventricular arrhythmogenesis in CHF rats. Methods and Results: CHF was induced in male Sprague-Dawley rats by surgical ligation of the left coronary artery. The data from 24-h continuous radiotelemetry ECG recording in conscious rats showed that ventricular tachycardia/fibrillation (VT/VF) occurred in 3 and 14-week CHF rats but not 8-week CHF rats. Additionally, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of left ventricular pressure rise (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in 14-week CHF rats but not 3 or 8-week CHF rats. Results from whole-cell patch clamp recording demonstrated that N-type Ca2+ currents in AVG neurons began to decrease in 8-week CHF rats, and that there was also a significant decrease in 14-week CHF rats. Correlation analysis revealed that N-type Ca2+ currents in AVG neurons negatively correlated with the cumulative duration of VT/VF in 14-week CHF rats, whereas there was no correlation between N-type Ca2+ currents in AVG neurons and the cumulative duration of VT/VF in 3-week CHF. Conclusion: Malignant ventricular arrhythmias mainly occur in the early and late stages of CHF. Electrical remodeling of AVG neurons highly correlates with the occurrence of ventricular arrhythmias in the late stage of CHF.
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Affiliation(s)
- Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Chaojun Wang
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA.,Department of Cardiovascular Disease, The First Affiliated Hospital of Xi'an Jiaotong UniversityXi'an, China
| | - Liang Cao
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA.,Department of Cardiac Surgery, Second Xiangya Hospital, Central South UniversityChangsha, China
| | - Robert L Muelleman
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Michael C Wadman
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA.,Department of Cellular & Integrative Physiology, University of Nebraska Medical CenterOmaha, NE, USA
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102
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103
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Toledo C, Andrade DC, Lucero C, Arce-Alvarez A, Díaz HS, Aliaga V, Schultz HD, Marcus NJ, Manríquez M, Faúndez M, Del Rio R. Cardiac diastolic and autonomic dysfunction are aggravated by central chemoreflex activation in heart failure with preserved ejection fraction rats. J Physiol 2017; 595:2479-2495. [PMID: 28181258 DOI: 10.1113/jp273558] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/31/2017] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Heart failure with preserved ejection fraction (HFpEF) is associated with disordered breathing patterns, and sympatho-vagal imbalance. Although it is well accepted that altered peripheral chemoreflex control plays a role in the progression of heart failure with reduced ejection fraction (HFrEF), the pathophysiological mechanisms underlying deterioration of cardiac function in HFpEF are poorly understood. We found that central chemoreflex is enhanced in HFpEF and neuronal activation is increased in pre-sympathetic regions of the brainstem. Our data showed that activation of the central chemoreflex pathway in HFpEF exacerbates diastolic dysfunction, worsens sympatho-vagal imbalance and markedly increases the incidence of cardiac arrhythmias in rats with HFpEF. ABSTRACT Heart failure (HF) patients with preserved ejection fraction (HFpEF) display irregular breathing, sympatho-vagal imbalance, arrhythmias and diastolic dysfunction. It has been shown that tonic activation of the central and peripheral chemoreflex pathway plays a pivotal role in the pathophysiology of HF with reduced ejection fraction. In contrast, no studies to date have addressed chemoreflex function or its effect on cardiac function in HFpEF. Therefore, we tested whether peripheral and central chemoreflexes are hyperactive in HFpEF and if chemoreflex activation exacerbates cardiac dysfunction and autonomic imbalance. Sprague-Dawley rats (n = 32) were subjected to sham or volume overload to induce HFpEF. Resting breathing variability, chemoreflex gain, cardiac function and sympatho-vagal balance, and arrhythmia incidence were studied. HFpEF rats displayed [mean ± SD; chronic heart failure (CHF) vs. Sham, respectively] a marked increase in the incidence of apnoeas/hypopnoeas (20.2 ± 4.0 vs. 9.7 ± 2.6 events h-1 ), autonomic imbalance [0.6 ± 0.2 vs. 0.2 ± 0.1 low/high frequency heart rate variability (LF/HFHRV )] and cardiac arrhythmias (196.0 ± 239.9 vs. 19.8 ± 21.7 events h-1 ). Furthermore, HFpEF rats showed increase central chemoreflex sensitivity but not peripheral chemosensitivity. Accordingly, hypercapnic stimulation in HFpEF rats exacerbated increases in sympathetic outflow to the heart (229.6 ± 43.2% vs. 296.0 ± 43.9% LF/HFHRV , normoxia vs. hypercapnia, respectively), incidence of cardiac arrhythmias (196.0 ± 239.9 vs. 576.7 ± 472.9 events h-1 ) and diastolic dysfunction (0.008 ± 0.004 vs. 0.027 ± 0.027 mmHg μl-1 ). Importantly, the cardiovascular consequences of central chemoreflex activation were related to sympathoexcitation since these effects were abolished by propranolol. The present results show that the central chemoreflex is enhanced in HFpEF and that acute activation of central chemoreceptors leads to increases of cardiac sympathetic outflow, cardiac arrhythmogenesis and impairment in cardiac function in rats with HFpEF.
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Affiliation(s)
- Camilo Toledo
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Claudia Lucero
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Alexis Arce-Alvarez
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Hugo S Díaz
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Valentín Aliaga
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Centre, Omaha, NE, USA
| | - Noah J Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA, USA
| | - Mónica Manríquez
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Marcelo Faúndez
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
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104
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Wang HJ, Rozanski GJ, Zucker IH. Cardiac sympathetic afferent reflex control of cardiac function in normal and chronic heart failure states. J Physiol 2017; 595:2519-2534. [PMID: 28116751 DOI: 10.1113/jp273764] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 01/17/2017] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Cardiac sympathetic afferents are considered to be essential pathways for transmission of cardiac nociception to the central nervous system during myocardial ischaemia. However, a potential contribution of the CSAR control of cardiac dysfunction in both normal and chronic heart failure (CHF) states remains unknown. We found that activation of the CSAR evokes little increase in cardiac contractility with an exaggerated peripheral vasoconstriction in the CHF state. CSAR inhibition by epicardial lidocaine decreased cardiac contractility to a greater extent in CHF rats than sham rats. Furthermore, we also found that epicardial lidocaine paradoxically decreased left ventricular end-diastolic pressure (LVEDP) and left ventricular end-diastolic volume (preload) in CHF rats, which was not observed in sham rats. Chronic ablation of the CSAR by epicardial application of the afferent neurotoxin, RTX, selectively lowered diastolic blood pressure CHF rats. The observation suggests that CSAR has a differential effect on cardiac function in normal and CHF states. CSAR activation in normal state causes significant increase in cardiac contractility and cardiac output. ABSTRACT The enhanced 'cardiac sympathetic afferent reflex' (CSAR) critically contributes to the exaggerated global sympathetic tone in chronic heart failure (CHF). However, a potential contribution of the cardio-cardiac reflex control of cardiac function in both normal and CHF states remains unknown. In this study, we evaluated the effects of direct activation or inhibition of the CSAR on cardiac function by pressure-volume (P-V) loop analysis in ∼12-week sham-operated and myocardial infarcted (MI) rats. In sham rats, acute CSAR activation by epicardial application of bradykinin (BK) increased heart rate (HR), left ventricular systolic pressure (LVSP), the maximum first derivative of left ventricular pressure (dp/dtmax ), and the slope of the end-systolic P-V relationship (ESPVR), suggesting that acute CSAR activation in the normal state enhances myocardial contractility. CSAR activation also decreased left ventricular (LV) systolic and diastolic volumes with little effect on LV end-diastolic pressure (LVEDP) or the end-diastolic P-V relationship (EDPVR) in sham rats. Compared to sham, CHF rats exhibit a reduced increase in the slope of the ESPVR and dp/dtmax in response to BK, indicating a poor contractile response to CSAR activation. Interestingly, BK application in CHF rats increased cardiac systolic and diastolic volumes and further increased the elevated LVEDP, neither of which was seen in sham rats. Following CSAR inhibition by epicardial lidocaine, blood pressure, HR, LVSP, dp/dt, LVEDP and ESPVR decreased in CHF rats whereas lidocaine had little effect in sham rats, indicating that the CSAR is tonically active in CHF and contributes to cardiac dysfunction. Furthermore, we found that epicardial lidocaine paradoxically decreased LV end-diastolic volume (preload) in CHF rats, which was not observed in sham rats. The decreased preload by lidocaine in CHF rats may be due to a reduction in peripheral vascular resistance since epicardial lidocaine significantly lowered peripheral (renal) sympathetic nerve activity in CHF rats but not in sham rats. Furthermore, chronic ablation of CSAR by epicardial application of a selective afferent neurotoxin, resiniferatoxin, selectively lowered diastolic blood pressure both at daytime and night-time with less effect on systolic blood pressure in CHF rats. Our data suggest that there is an imbalance between cardiac and peripheral responses to CSAR in CHF animals compared to sham-operated controls.
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Affiliation(s)
- Han-Jun Wang
- Department of Anesthesiology, University of Nebraska Medical Center, 984455 Nebraska Medical Center, Omaha, NE, 68198-4455, USA.,Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE, 68198-5850, USA
| | - George J Rozanski
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE, 68198-5850, USA
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE, 68198-5850, USA
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105
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Conde SV, Ribeiro MJ, Melo BF, Guarino MP, Sacramento JF. Insulin resistance: a new consequence of altered carotid body chemoreflex? J Physiol 2017; 595:31-41. [PMID: 27027507 PMCID: PMC5199745 DOI: 10.1113/jp271684] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/11/2016] [Indexed: 01/22/2023] Open
Abstract
Metabolic diseases affect millions of individuals across the world and represent a group of chronic diseases of very high prevalence and relatively low therapeutic success, making them suitable candidates for pathophysiological studies. The sympathetic nervous system (SNS) contributes to the regulation of energy balance and energy expenditure both in physiological and pathological states. For instance, drugs that stimulate sympathetic activity decrease food intake, increase resting metabolic rate and increase the thermogenic response to food, while pharmacological blockade of the SNS has opposite effects. Likewise, dysmetabolic features such as insulin resistance, dyslipidaemia and obesity are characterized by a basal overactivation of the SNS. Recently, a new line of research linking the SNS to metabolic diseases has emerged with the report that the carotid bodies (CBs) are involved in the development of insulin resistance. The CBs are arterial chemoreceptors that classically sense changes in arterial blood O2 , CO2 and pH levels and whose activity is known to be increased in rodent models of insulin resistance. We have shown that selective bilateral resection of the nerve of the CB, the carotid sinus nerve (CSN), totally prevents diet-induced insulin resistance, hyperglycaemia, dyslipidaemia, hypertension and sympathoadrenal overactivity. These results imply that the beneficial effects of CSN resection on insulin action and glucoregulation are modulated by target-related efferent sympathetic nerves through a reflex that is initiated in the CBs. It also highlights modulation of CB activity as a putative future therapeutic intervention for metabolic diseases.
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Affiliation(s)
- Silvia V. Conde
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
| | - Maria J. Ribeiro
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
| | - Bernardete F. Melo
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
| | - Maria P. Guarino
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
- UIS‐Unidade de Investigação em Saúde – Escola Superior de Saúde de Leiria – Instituto Politécnico de LeiriaLeiriaPortugal
| | - Joana F. Sacramento
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
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106
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Abstract
Autonomic dysfunction is a frequent and relevant complication of diabetes mellitus, as it is associated with increased morbidity and mortality. In addition, it is today considered as predictive of the most severe diabetic complications, like nephropathy and retinopathy. The classical methods of screening are the cardiovascular reflex tests and were originally interpreted as evidence of nerve damage. A more modern approach, based on the integrated control of cardiovascular and respiratory function, reveals that these abnormalities are to a great extent functional, at least in the early stage of the disease, thus suggesting new potential interventions. Therefore, this review aims to go further investigating how the imbalance of the autonomic nervous system is altered and can be influenced in many chronic pathologies through a global view of cardio-respiratory and metabolic interactions and how the same mechanisms are applicable to diabetes.
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Affiliation(s)
- Luciano Bernardi
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, University of Helsinki, Helsinki, Finland.
- Research Program Unit, Diabetes and Obesity, University of Helsinki, Helsinki, Finland.
- , Villaggio dei Pioppi 2, 27020, Torre d'Isola, Italy.
| | - Lucio Bianchi
- Department of Endocrinology-Diabetology-Nutrition, Jean Verdier Hospital, AP-HP, CRNH-IdF, Paris-Nord University, Bondy, France
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107
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Pijacka W, McBryde FD, Marvar PJ, Lincevicius GS, Abdala APL, Woodward L, Li D, Paterson DJ, Paton JFR. Carotid sinus denervation ameliorates renovascular hypertension in adult Wistar rats. J Physiol 2016; 594:6255-6266. [PMID: 27510951 DOI: 10.1113/jp272708] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/03/2016] [Indexed: 01/24/2023] Open
Abstract
KEY POINTS Peripheral chemoreflex sensitization is a feature of renovascular hypertension. Carotid sinus nerve denervation (CSD) has recently been shown to relieve hypertension and reduce sympathetic activity in other rat models of hypertension. We show that CSD in renovascular hypertension halts further increases in blood pressure. Possible mechanisms include improvements in baroreceptor reflex sensitivity and renal function, restoration of cardiac calcium signalling towards control levels, and reduced neural inflammation. Our data suggest that the peripheral chemoreflex may be a viable therapeutic target for renovascular hypertension. ABSTRACT The peripheral chemoreflex is known to be hyper-responsive in both spontaneously hypertensive (SHR) and Goldblatt hypertensive (two kidney one clip; 2K1C) rats. We have previously shown that carotid sinus nerve denervation (CSD) reduces arterial blood pressure (ABP) in SHR. In the present study, we show that CSD ameliorates 2K1C hypertension and reveal the potential underlying mechanisms. Adult Wistar rats were instrumented to record ABP via telemetry, and then underwent CSD (n = 9) or sham CSD (n = 9) 5 weeks after renal artery clipping, in comparison with normal Wistar rats (n = 5). After 21 days, renal function was assessed, and tissue was collected to assess sympathetic postganglionic intracellular calcium transients ([Ca2+ ]i ) and immune cell infiltrates. Hypertensive 2K1C rats showed a profound elevation in ABP (Wistar: 98 ± 4 mmHg vs. 2K1C: 147 ± 8 mmHg; P < 0.001), coupled with impairments in renal function and baroreflex sensitivity, increased neuroinflammatory markers and enhanced [Ca2+ ]I in stellate neurons (P < 0.05). CSD reduced ABP in 2K1C+CSD rats and prevented the further progressive increase in ABP seen in 2K1C+sham CSD rats, with a between-group difference of 14 ± 2 mmHg by week 3 (P < 0.01), which was accompanied by improvements in both baroreflex control and spectral indicators of cardiac sympatho-vagal balance. Furthermore, CSD improved protein and albuminuria, decreased [Ca2+ ]i evoked responses from stellate neurons, and also reduced indicators of brainstem inflammation. In summary, CSD in 2K1C rats reduces the hypertensive burden and improves renal function. This may be mediated by improvements in autonomic balance, functional remodelling of post-ganglionic neurons and reduced inflammation. Our results suggest that the peripheral chemoreflex may be considered as a potential therapeutic target for controlling renovascular hypertension.
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Affiliation(s)
- Wioletta Pijacka
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Fiona D McBryde
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK.,Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Marvar
- Department of Pharmacology and Physiology, The George Washington University School of Medical and Health Sciences, Washington, DC, USA
| | - Gisele S Lincevicius
- Cardiovascular Division - Department of Physiology, Escola Paulista de Medicina, Universidade Federal de, Sao Paulo, Brazil
| | - Ana P L Abdala
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Lavinia Woodward
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - Dan Li
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - Julian F R Paton
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK.
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108
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Niewinski P, Janczak D, Rucinski A, Tubek S, Engelman ZJ, Piesiak P, Jazwiec P, Banasiak W, Fudim M, Sobotka PA, Javaheri S, Hart EC, Paton JF, Ponikowski P. Carotid body resection for sympathetic modulation in systolic heart failure: results from first-in-man study. Eur J Heart Fail 2016; 19:391-400. [DOI: 10.1002/ejhf.641] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 07/10/2016] [Accepted: 07/25/2016] [Indexed: 12/30/2022] Open
Affiliation(s)
- Piotr Niewinski
- Department of Cardiology, Centre for Heart Disease; 4th Military Hospital; Wroclaw Poland
| | - Dariusz Janczak
- Department of Vascular Surgery; 4th Military Hospital; Wroclaw Poland
| | - Artur Rucinski
- Department of Vascular Surgery; 4th Military Hospital; Wroclaw Poland
| | - Stanislaw Tubek
- Department of Cardiology, Centre for Heart Disease; 4th Military Hospital; Wroclaw Poland
- Department of Heart Diseases, Faculty of Health Sciences; Wroclaw Medical University; Wroclaw Poland
| | | | - Pawel Piesiak
- Department of Pulmonology and Lung Cancer; Medical University; Wroclaw Poland
| | - Przemyslaw Jazwiec
- Department of Radiology and Diagnostics Imaging; 4th Military Hospital; Wroclaw Poland
| | - Waldemar Banasiak
- Department of Cardiology, Centre for Heart Disease; 4th Military Hospital; Wroclaw Poland
| | - Marat Fudim
- Department of Cardiology; Duke University School of Medicine; Durham NC USA
| | - Paul A. Sobotka
- Cibiem Inc.; Los Altos CA USA
- The Ohio State University; Columbus OH USA
| | - Shahrokh Javaheri
- Bethesda North Hospital; Cincinnati OH USA
- University of Cincinnati; Cincinnati OH USA
| | - Emma C.J. Hart
- School of Physiology and Pharmacology, Clinical Research & Imaging Centre; University of Bristol; Bristol UK
| | - Julian F.R. Paton
- School of Physiology and Pharmacology, Clinical Research & Imaging Centre; University of Bristol; Bristol UK
| | - Piotr Ponikowski
- Department of Cardiology, Centre for Heart Disease; 4th Military Hospital; Wroclaw Poland
- Department of Heart Diseases, Faculty of Health Sciences; Wroclaw Medical University; Wroclaw Poland
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109
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Tubek S, Niewinski P, Reczuch K, Janczak D, Rucinski A, Paleczny B, Engelman ZJ, Banasiak W, Paton JFR, Ponikowski P. Effects of selective carotid body stimulation with adenosine in conscious humans. J Physiol 2016; 594:6225-6240. [PMID: 27435894 DOI: 10.1113/jp272109] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 07/12/2016] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS In humans, excitation of peripheral chemoreceptors with systemic hypoxia causes hyperventilation, hypertension and tachycardia. However, the contribution of particular chemosensory areas (carotid vs. aortic bodies) to this response is unclear. We showed that selective stimulation of the carotid body by the injection of adenosine into the carotid artery causes a dose-dependent increase in minute ventilation and blood pressure with a concomitant decrease in heart rate in conscious humans. The ventilatory response was abolished and the haemodynamic response was diminished following carotid body ablation. We found that the magnitude of adenosine evoked responses in minute ventilation and blood pressure was analogous to the responses evoked by hypoxia. By contrast, opposing heart rate responses were evoked by adenosine (bradycardia) vs. hypoxia (tachycardia). Intra-carotid adenosine administration may provide a novel method for perioperative assessment of the effectiveness of carotid body ablation, which has been recently proposed as a treatment strategy for sympathetically-mediated diseases. ABSTRACT Stimulation of peripheral chemoreceptors by acute hypoxia causes an increase in minute ventilation (VI), heart rate (HR) and arterial blood pressure (BP). However, the contribution of particular chemosensory areas, such as carotid (CB) vs. aortic bodies, to this response in humans remains unknown. We performed a blinded, randomized and placebo-controlled study in 11 conscious patients (nine men, two women) undergoing common carotid artery angiography. Doses of adenosine ranging from 4 to 512 μg or placebo solution of a matching volume were administered in randomized order via a diagnostic catheter located in a common carotid artery. Separately, ventilatory and haemodynamic responses to systemic hypoxia were also assessed. Direct excitation of a CB with intra-arterial adenosine increased VI, systolic BP, mean BP and decreased HR. No responses in these variables were seen after injections of placebo. The magnitude of the ventilatory and haemodynamic responses depended on both the dose of adenosine used and on the level of chemosensitivity as determined by the ventilatory response to hypoxia. Percutaneous radiofrequency ablation of the CB abolished the adenosine evoked respiratory response and partially depressed the cardiovascular response in one participant. The results of the present study confirm the excitatory role of purines in CB physiology in humans and suggest that adenosine may be used for selective stimulation and assessment of CB activity. The trial is registered at ClinicalTrials.gov NCT01939912.
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Affiliation(s)
- Stanislaw Tubek
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland. .,Department of Heart Diseases, Faculty of Health Sciences, Wroclaw Medical University, Wroclaw, Poland.
| | - Piotr Niewinski
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland
| | - Krzysztof Reczuch
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland.,Department of Heart Diseases, Faculty of Health Sciences, Wroclaw Medical University, Wroclaw, Poland
| | - Dariusz Janczak
- Department of Vascular Surgery, 4th Military Hospital, Wroclaw, Poland.,Department of Clinical Proceedings, Faculty of Health Sciences, Wroclaw Medical University, Wroclaw, Poland
| | - Artur Rucinski
- Department of Vascular Surgery, 4th Military Hospital, Wroclaw, Poland
| | | | | | - Waldemar Banasiak
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland
| | - Julian F R Paton
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Piotr Ponikowski
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland.,Department of Heart Diseases, Faculty of Health Sciences, Wroclaw Medical University, Wroclaw, Poland
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110
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Del Rio R, Andrade DC, Lucero C, Arias P, Iturriaga R. Carotid Body Ablation Abrogates Hypertension and Autonomic Alterations Induced by Intermittent Hypoxia in Rats. Hypertension 2016; 68:436-45. [PMID: 27381902 DOI: 10.1161/hypertensionaha.116.07255] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 05/06/2016] [Indexed: 01/12/2023]
Abstract
Chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea, enhances carotid body (CB) chemosensory responses to hypoxia and produces autonomic dysfunction, cardiac arrhythmias, and hypertension. We tested whether autonomic alterations, arrhythmogenesis, and the progression of hypertension induced by CIH depend on the enhanced CB chemosensory drive, by ablation of the CB chemoreceptors. Male Sprague-Dawley rats were exposed to control (Sham) conditions for 7 days and then to CIH (5% O2, 12/h 8 h/d) for a total of 28 days. At 21 days of CIH exposure, rats underwent bilateral CB ablation and then exposed to CIH for 7 additional days. Arterial blood pressure and ventilatory chemoreflex response to hypoxia were measured in conscious rats. In addition, cardiac autonomic imbalance, cardiac baroreflex gain, and arrhythmia score were assessed during the length of the experiments. In separate experimental series, we measured extracellular matrix remodeling content in cardiac atrial tissue and systemic oxidative stress. CIH induced hypertension, enhanced ventilatory response to hypoxia, induced autonomic imbalance toward sympathetic preponderance, reduced baroreflex gain, and increased arrhythmias and atrial fibrosis. CB ablation normalized blood pressure, reduced ventilatory response to hypoxia, and restored cardiac autonomic and baroreflex function. In addition, CB ablation reduced the number of arrhythmias, but not extracellular matrix remodeling or systemic oxidative stress, suggesting that reductions in arrhythmia incidence during CIH were related to normalization of cardiac autonomic balance. Present results show that autonomic alterations induced by CIH are critically dependent on the CB and support a main role for the CB in the CIH-induced hypertension.
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Affiliation(s)
- Rodrigo Del Rio
- From the Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile (R.D.R., C.L.); and Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile (D.C.A., P.A., R.I.)
| | - David C Andrade
- From the Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile (R.D.R., C.L.); and Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile (D.C.A., P.A., R.I.)
| | - Claudia Lucero
- From the Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile (R.D.R., C.L.); and Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile (D.C.A., P.A., R.I.)
| | - Paulina Arias
- From the Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile (R.D.R., C.L.); and Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile (D.C.A., P.A., R.I.)
| | - Rodrigo Iturriaga
- From the Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile (R.D.R., C.L.); and Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile (D.C.A., P.A., R.I.).
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111
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Mozer MT, Holbein WW, Joyner MJ, Curry TB, Limberg JK. Reductions in carotid chemoreceptor activity with low-dose dopamine improves baroreflex control of heart rate during hypoxia in humans. Physiol Rep 2016; 4:e12859. [PMID: 27418545 PMCID: PMC4945841 DOI: 10.14814/phy2.12859] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/13/2016] [Accepted: 06/18/2016] [Indexed: 11/24/2022] Open
Abstract
The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of heart rate with exposure to hypoxia. We hypothesized spontaneous cardiac baroreflex sensitivity (scBRS) would be reduced with hypoxia and this effect would be blunted when carotid chemoreceptor activity was reduced with low-dose dopamine. Fifteen healthy adults (11 M/4 F) completed two visits randomized to intravenous dopamine or placebo (saline). On each visit, subjects were exposed to 5-min normoxia (~99% SpO2), followed by 5-min hypoxia (~84% SpO2). Blood pressure (intra-arterial catheter) and heart rate (ECG) were measured continuously and scBRS was assessed by spectrum and sequence methodologies. scBRS was reduced with hypoxia (P < 0.01). Using the spectrum analysis approach, the fall in scBRS with hypoxia was attenuated with infusion of low-dose dopamine (P < 0.01). The decrease in baroreflex sensitivity to rising pressures (scBRS "up-up") was also attenuated with low-dose dopamine (P < 0.05). However, dopamine did not attenuate the decrease in baroreflex sensitivity to falling pressures (scBRS "down-down"; P > 0.05). Present findings are consistent with a reduction in scBRS with systemic hypoxia. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when activity of the chemoreceptors is reduced with low-dose dopamine. However, the improvement in scBRS with dopamine appears to be specific to rising blood pressures. These results may have important implications for impairments in baroreflex function common in disease states of acute and/or chronic hypoxemia, as well as the experimental use of dopamine to assess such changes.
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Affiliation(s)
- Michael T Mozer
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| | | | | | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
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112
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Toledo C, Andrade DC, Lucero C, Schultz HD, Marcus N, Retamal M, Madrid C, Del Rio R. Contribution of peripheral and central chemoreceptors to sympatho-excitation in heart failure. J Physiol 2016; 595:43-51. [PMID: 27218485 DOI: 10.1113/jp272075] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/20/2016] [Indexed: 12/18/2022] Open
Abstract
Chronic heart failure (CHF) is a major public health problem. Tonic hyper-activation of sympathetic neural outflow is commonly observed in patients with CHF. Importantly, sympatho-excitation in CHF exacerbates its progression and is strongly related to poor prognosis and high mortality risk. Increases in both peripheral and central chemoreflex drive are considered markers of the severity of CHF. The principal peripheral chemoreceptors are the carotid bodies (CBs) and alteration in their function has been described in CHF. Mainly, during CHF the CB chemosensitivity is enhanced leading to increases in ventilation and sympathetic outflow. In addition to peripheral control of breathing, central chemoreceptors (CCs) are considered a dominant mechanism in ventilatory regulation. Potentiation of the ventilatory and sympathetic drive in response to CC activation has been shown in patients with CHF as well as in animal models. Therefore, improving understanding of the contribution of the peripheral and central chemoreflexes to augmented sympathetic discharge in CHF could help in developing new therapeutic approaches intended to attenuate the progression of CHF. Accordingly, the main focus of this review is to discuss recent evidence that peripheral and central chemoreflex function are altered in CHF and that they contribute to autonomic imbalance and progression of CHF.
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Affiliation(s)
- Camilo Toledo
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - Claudia Lucero
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Noah Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA, USA
| | - Mauricio Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Carlos Madrid
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
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113
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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: 116] [Impact Index Per Article: 14.5] [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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114
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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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115
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Niewinski P. Carotid body modulation in systolic heart failure from the clinical perspective. J Physiol 2016; 595:53-61. [PMID: 26990354 DOI: 10.1113/jp271692] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 03/10/2016] [Indexed: 01/30/2023] Open
Abstract
Augmented sensitivity of peripheral chemoreceptors (PChS) is a common finding in systolic heart failure (HF). It is related to lower left ventricle systolic function, higher plasma concentrations of natriuretic peptides, worse exercise tolerance and greater prevalence of atrial fibrillation compared to patients with normal PChS. The magnitude of ventilatory response to the activation of peripheral chemoreceptors is proportional to the level of heart rate (tachycardia) and blood pressure (hypertension) responses. All these responses can be measured non-invasively in a safe and reproducible fashion using different methods employing either hypoxia or hypercapnia. Current interventions aimed at modulation of peripheral chemoreceptors in HF are focused on carotid bodies (CBs). There is a clear link between afferent signalling from CBs and sympathetic overactivity, which remains the priority target of modern HF treatment. However, CB modulation therapies may face several potential obstacles: (1) As evidenced by HF trials, an excessive inhibition of sympathetic system may be harmful. (2) Proximity of critical anatomical structures (important vessels and nerves) makes surgical and transcutaneous interventions on CB technically demanding. (3) Co-existence of atherosclerosis in the area of carotid artery bifurcation increases the risk of central embolic events related to CB modulation. (4) The relative contribution of CBs vs. aortic bodies to sympathetic activation in HF patients is unclear. (5) Choosing optimal candidates for CB modulation from the population of HF patients may be problematic. (6) There is a risk of nocturnal hypoxia following CB ablation - mostly after bilateral procedures and in patients with concomitant obstructive sleep apnoea.
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Affiliation(s)
- Piotr Niewinski
- Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
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116
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Kuntze LB, Ferreira-Junior NC, Lagatta DC, Resstel LBM. Ventral hippocampus modulates bradycardic response to peripheral chemoreflex activation in awake rats. Exp Physiol 2016; 101:482-93. [PMID: 26700468 DOI: 10.1113/ep085393] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/22/2015] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does reversible synaptic inactivation by CoCl2 in the dorsal (DH) or ventral (VH) portions of the hippocampus have a modulatory effect on cardiovascular and respiratory responses evoked by chemoreflex activation in awake rats? What is the main finding and its importance? Using i.v. infusion of KCN to activate the peripheral chemoreflex before and after microinjection of CoCl2 into VH, we showed that the bradycardic response was increased, but not the pressor and tachypnoeic responses even if the tidal volume had been increased. Thus, VH but not DH may be involved in the modulation of the parasympathoexcitatory component of the peripheral chemoreflex. In rats, peripheral chemoreflex activation evokes pressor and bradycardic responses as well as a tachypnoeic response. Studies have shown that limbic structures, such as the hippocampus, can modulate autonomic reflexes. Evidence suggests that the dorsal (DH) and the ventral (VH) portions of the hippocampus are structurally and functionally distinct; therefore, in the present study we tested the hypothesis that local neurotransmission of the DH and VH are involved in the neural pathways of the cardiovascular and ventilatory responses to chemoreflex activation. Thus, the goal of the present study was to compare the chemoreflex responses elicited by i.v. injection of KCN (40 μg per rat) in awake rats before and after DH and VH synaptic transmission was temporarily inhibited by bilateral microinjections of 500 nl of the unspecific synapse blocker, CoCl2 (1 mm). Bilateral inhibition of VH, but not DH, 10 min before KCN infusion was able to enhance the bradycardic response (P < 0.05), with no changes in the typical pressor and tachypnoeic responses evoked by chemoreflex activation (P > 0.05). Furthermore, the tidal volume was significantly increased (P < 0.05) even though no other respiratory parameter had been significantly changed (P > 0.05), suggesting that VH can exert a tonic modulatory action on tidal volume. Therefore, the present study reports, for the first time, that DH neurotransmission did not exert an influence on chemoreflex responses, whereas VH mediates, at least in part, the parasympathoexcitatory component of the peripheral chemoreflex.
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Affiliation(s)
- Luciana Bärg Kuntze
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14090-090, Brazil
| | - Nilson Carlos Ferreira-Junior
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14090-090, Brazil
| | - Davi Campos Lagatta
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14090-090, Brazil
| | - Leonardo Barbosa Moraes Resstel
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14090-090, Brazil
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117
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Basting TM, Abe C, Viar KE, Stornetta RL, Guyenet PG. Is plasticity within the retrotrapezoid nucleus responsible for the recovery of the PCO2 set-point after carotid body denervation in rats? J Physiol 2016; 594:3371-90. [PMID: 26842799 DOI: 10.1113/jp272046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Arterial PCO2 is kept constant via breathing adjustments elicited, at least partly, by central chemoreceptors (CCRs) and the carotid bodies (CBs). The CBs may be active in a normal oxygen environment because their removal reduces breathing. Thereafter, breathing slowly returns to normal. In the present study, we investigated whether an increase in the activity of CCRs accounts for this return. One week after CB excision, the hypoxic ventilatory reflex was greatly reduced as expected, whereas ventilation and blood gases at rest under normoxia were normal. Optogenetic inhibition of Phox2b-expressing neurons including the retrotrapezoid nucleus, a cluster of CCRs, reduced breathing proportionally to arterial pH. The hypopnoea was greater after CB excision but only in a normal or hypoxic environment. The difference could be simply explained by the loss of fast feedback from the CBs. We conclude that, in rats, CB denervation may not produce CCR plasticity. We also question whether the transient hypoventilation elicited by CB denervation means that these afferents are active under normoxia. ABSTRACT Carotid body denervation (CBD) causes hypoventilation and increases the arterial PCO2 set-point; these effects eventually subside. The hypoventilation is attributed to reduced CB afferent activity and the PCO2 set-point recovery to CNS plasticity. In the present study, we investigated whether the retrotrapezoid nucleus (RTN), a group of non-catecholaminergic Phox2b-expressing central respiratory chemoreceptors (CCRs), is the site of such plasticity. We evaluated the contribution of the RTN to breathing frequency (FR ), tidal volume (VT ) and minute volume (VE ) by inhibiting this nucleus optogenetically for 10 s (archaerhodopsinT3.0) in unanaesthetized rats breathing various levels of O2 and/or CO2 . The measurements were made in seven rats before and 6-7 days after CBD and were repeated in seven sham-operated rats. Seven days post-CBD, blood gases and ventilation in 21% O2 were normal, whereas the hypoxic ventilatory reflex was still depressed (95.3%) and hypoxia no longer evoked sighs. Sham surgery had no effect. In normoxia or hypoxia, RTN inhibition produced a more sustained hypopnoea post-CBD than before; in hyperoxia, the responses were identical. Post-CBD, RTN inhibition reduced FR and VE in proportion to arterial pH or PCO2 (ΔVE : 3.3 ± 1.5% resting VE /0.01 pHa). In these rats, 20.7 ± 8.9% of RTN neurons expressed archaerhodopsinT3.0. Hypercapnia (3-6% FiCO2 ) increased FR and VT in CBD rats (n = 4). In conclusion, RTN regulates FR and VE in a pH-dependent manner after CBD, consistent with its postulated CCR function. RTN inhibition produces a more sustained hypopnoea after CBD than before, although this change may simply result from the loss of the fast feedback action of the CBs.
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Affiliation(s)
- Tyler M Basting
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Chikara Abe
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Kenneth E Viar
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
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118
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Iturriaga R, Del Rio R, Idiaquez J, Somers VK. Carotid body chemoreceptors, sympathetic neural activation, and cardiometabolic disease. Biol Res 2016; 49:13. [PMID: 26920146 PMCID: PMC4768417 DOI: 10.1186/s40659-016-0073-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/12/2016] [Indexed: 11/10/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor that senses the arterial PO2, PCO2 and pH. In response to hypoxemia, hypercapnia and acidosis, carotid chemosensory discharge elicits reflex respiratory, autonomic and cardiovascular adjustments. The classical construct considers the CB as the main peripheral oxygen sensor, triggering reflex physiological responses to acute hypoxemia and facilitating the ventilatory acclimation to chronic hypoxemia at high altitude. However, a growing body of experimental evidence supports the novel concept that an abnormally enhanced CB chemosensory input to the brainstem contributes to overactivation
of the sympathetic nervous system, and consequent pathology. Indeed, the CB has been implicated in several diseases associated with increases in central sympathetic outflow. These include hypertension, heart failure, sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome. Indeed, ablation of the CB has been proposed for the treatment of severe and resistant hypertension in humans. In this review, we will analyze and discuss new evidence supporting an important role for the CB chemoreceptor in the progression of autonomic and cardiorespiratory alterations induced by heart failure, obstructive sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Centro de Investigación Biomédica, Universidad Autónoma de Chile, Santiago, Chile. .,Dirección de Investigación, Universidad Científica del Sur, Lima, Peru.
| | - Juan Idiaquez
- Catedra de Neurología, Escuela de Medicina, Universidad de Valparaíso, Valparaíso, Chile.
| | - Virend K Somers
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
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119
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Laitano O, Ahn B, Patel N, Coblentz PD, Smuder AJ, Yoo JK, Christou DD, Adhihetty PJ, Ferreira LF. Pharmacological targeting of mitochondrial reactive oxygen species counteracts diaphragm weakness in chronic heart failure. J Appl Physiol (1985) 2016; 120:733-42. [PMID: 26846552 DOI: 10.1152/japplphysiol.00822.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/28/2016] [Indexed: 12/15/2022] Open
Abstract
Diaphragm muscle weakness in chronic heart failure (CHF) is caused by elevated oxidants and exacerbates breathing abnormalities, exercise intolerance, and dyspnea. However, the specific source of oxidants that cause diaphragm weakness is unknown. We examined whether mitochondrial reactive oxygen species (ROS) cause diaphragm weakness in CHF by testing the hypothesis that CHF animals treated with a mitochondria-targeted antioxidant have normal diaphragm function. Rats underwent CHF or sham surgery. Eight weeks after surgeries, we administered a mitochondrial-targeted antioxidant (MitoTEMPO; 1 mg·kg(-1)·day(-1)) or sterile saline (Vehicle). Left ventricular dysfunction (echocardiography) pre- and posttreatment and morphological abnormalities were consistent with the presence of CHF. CHF elicited a threefold (P < 0.05) increase in diaphragm mitochondrial H2O2 emission, decreased diaphragm glutathione content by 23%, and also depressed twitch and maximal tetanic force by ∼20% in Vehicle-treated animals compared with Sham (P < 0.05 for all comparisons). Diaphragm mitochondrial H2O2 emission, glutathione content, and twitch and maximal tetanic force were normal in CHF animals receiving MitoTEMPO. Neither CHF nor MitoTEMPO altered the diaphragm protein levels of antioxidant enzymes: superoxide dismutases (CuZn-SOD or MnSOD), glutathione peroxidase, and catalase. In both Vehicle and MitoTEMPO groups, CHF elicited a ∼30% increase in cytochrome c oxidase activity, whereas there were no changes in citrate synthase activity. Our data suggest that elevated mitochondrial H2O2 emission causes diaphragm weakness in CHF. Moreover, changes in protein levels of antioxidant enzymes or mitochondrial content do not seem to mediate the increase in mitochondria H2O2 emission in CHF and protective effects of MitoTEMPO.
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Affiliation(s)
- Orlando Laitano
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Bumsoo Ahn
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Nikhil Patel
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Philip D Coblentz
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Ashley J Smuder
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Jeung-Ki Yoo
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Demetra D Christou
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Peter J Adhihetty
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
| | - Leonardo F Ferreira
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida
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120
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Oxygen-sensing by arterial chemoreceptors: Mechanisms and medical translation. Mol Aspects Med 2016; 47-48:90-108. [DOI: 10.1016/j.mam.2015.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
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121
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Iturriaga R, Andrade DC, Del Rio R. Crucial Role of the Carotid Body Chemoreceptors on the Development of High Arterial Blood Pressure During Chronic Intermittent Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 860:255-60. [PMID: 26303489 DOI: 10.1007/978-3-319-18440-1_29] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Exposure to chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea, produces autonomic and cardiorespirartory alterations, and leads to systemic hypertension. These alterations are associated with enhanced carotid body (CB) chemosensory and ventilatory hypoxic reflexes and a decrease baroreflex (BRS) efficiency. The aim of this study was to determine the therapeutic effect of CB ablation on the elevated arterial blood pressure, the reduced BRS and the potentiated ventilatory response induced by CIH in conscious rats. Arterial blood pressure (BP) was continuous measured by telemetry in male Sprague-Dawley rats exposed to CIH (5 % O(2), 12 times/h, and 8 h/day). After 21 days of CIH, the CBs were selectively cryodestroyed, and rats were kept one more week in CIH. Ventilatory responses to hypoxia were assessed by whole body plethysmography and spontaneous BRS measured by the sequence method. Exposure to CIH produces hypertension, increased the chemoreflex ventilatory hypoxic responses, and decreased BRS. The ablation of the CBs normalized the elevated BP, and the altered ventilatory response and BRS. Present results suggest that the CB play a crucial role in the development of high arterial pressure and autonomic alterations induced by CIH.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile,
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Giannoni A, Mirizzi G, Aimo A, Emdin M, Passino C. Peripheral reflex feedbacks in chronic heart failure: Is it time for a direct treatment? World J Cardiol 2015; 7:824-828. [PMID: 26730288 PMCID: PMC4691809 DOI: 10.4330/wjc.v7.i12.824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/21/2015] [Accepted: 10/27/2015] [Indexed: 02/07/2023] Open
Abstract
Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure (HF), no single conceptual paradigm for HF has withstood the test of time. The last model that has been developed, the neurohormonal model, has the great virtue of highlighting the role of the heart as an endocrine organ, as well as to shed some light on the key role on HF progression of neurohormones and peripheral organs and tissues beyond the heart itself. However, while survival in clinical trials based on neurohormonal antagonist drugs has improved, HF currently remains a lethal condition. At the borders of the neurohormonal model of HF, a partially unexplored path trough the maze of HF pathophysiology is represented by the feedback systems. There are several evidences, from both animal studies and humans reports, that the deregulation of baro-, ergo- and chemo-reflexes in HF patients elicits autonomic imbalance associated with parasympathetic withdrawal and increased adrenergic drive to the heart, thus fundamentally contributing to the evolution of the disease. Hence, on top of guideline-recommended medical therapy, mainly based on neurohormonal antagonisms, all visceral feedbacks have been recently considered in HF patients as additional potential therapeutic targets.
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123
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Andrade DC, Lucero C, Toledo C, Madrid C, Marcus NJ, Schultz HD, Del Rio R. Relevance of the Carotid Body Chemoreflex in the Progression of Heart Failure. BIOMED RESEARCH INTERNATIONAL 2015; 2015:467597. [PMID: 26779536 PMCID: PMC4686619 DOI: 10.1155/2015/467597] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/08/2015] [Indexed: 12/18/2022]
Abstract
Chronic heart failure (CHF) is a global health problem affecting millions of people. Autonomic dysfunction and disordered breathing patterns are commonly observed in patients with CHF, and both are strongly related to poor prognosis and high mortality risk. Tonic activation of carotid body (CB) chemoreceptors contributes to sympathoexcitation and disordered breathing patterns in experimental models of CHF. Recent studies show that ablation of the CB chemoreceptors improves autonomic function and breathing control in CHF and improves survival. These exciting findings indicate that alterations in CB function are critical to the progression of CHF. Therefore, better understanding of the physiology of the CB chemoreflex in CHF could lead to improvements in current treatments and clinical management of patients with CHF characterized by high chemosensitivity. Accordingly, the main focus of this brief review is to summarize current knowledge of CB chemoreflex function in different experimental models of CHF and to comment on their potential translation to treatment of human CHF.
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Affiliation(s)
- David C. Andrade
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, 8900000 Santiago, Chile
| | - Claudia Lucero
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, 8900000 Santiago, Chile
| | - Camilo Toledo
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, 8900000 Santiago, Chile
| | - Carlos Madrid
- Centro de Fisiología Celular e Integrativa, Clínica Alemana-Universidad del Desarrollo, 7500000 Santiago, Chile
| | - Noah J. Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA 50312, USA
| | - Harold D. Schultz
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, 8900000 Santiago, Chile
- Dirección de Investigación, Universidad Científica del Sur, Lima 15067, Peru
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Del Rio R, Quintanilla RA, Orellana JA, Retamal MA. Neuron-Glia Crosstalk in the Autonomic Nervous System and Its Possible Role in the Progression of Metabolic Syndrome: A New Hypothesis. Front Physiol 2015; 6:350. [PMID: 26648871 PMCID: PMC4664731 DOI: 10.3389/fphys.2015.00350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/09/2015] [Indexed: 01/26/2023] Open
Abstract
Metabolic syndrome (MS) is characterized by the following physiological alterations: increase in abdominal fat, insulin resistance, high concentration of triglycerides, low levels of HDL, high blood pressure, and a generalized inflammatory state. One of the pathophysiological hallmarks of this syndrome is the presence of neurohumoral activation, which involve autonomic imbalance associated to hyperactivation of the sympathetic nervous system. Indeed, enhanced sympathetic drive has been linked to the development of endothelial dysfunction, hypertension, stroke, myocardial infarct, and obstructive sleep apnea. Glial cells, the most abundant cells in the central nervous system, control synaptic transmission, and regulate neuronal function by releasing bioactive molecules called gliotransmitters. Recently, a new family of plasma membrane channels called hemichannels has been described to allow the release of gliotransmitters and modulate neuronal firing rate. Moreover, a growing amount of evidence indicates that uncontrolled hemichannel opening could impair glial cell functions, affecting synaptic transmission and neuronal survival. Given that glial cell functions are disturbed in various metabolic diseases, we hypothesize that progression of MS may relies on hemichannel-dependent impairment of glial-to-neuron communication by a mechanism related to dysfunction of inflammatory response and mitochondrial metabolism of glial cells. In this manuscript, we discuss how glial cells may contribute to the enhanced sympathetic drive observed in MS, and shed light about the possible role of hemichannels in this process.
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Affiliation(s)
- Rodrigo Del Rio
- Centro de Investigación Biomédica, Universidad Autónoma de Chile Santiago, Chile ; Dirección de Investigación, Universidad Científica del Sur Lima, Perú
| | | | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina. Clínica Alemana Universidad del Desarrollo Santiago, Chile
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125
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Ramchandra R, Barrett CJ. Regulation of the renal sympathetic nerves in heart failure. Front Physiol 2015; 6:238. [PMID: 26388778 PMCID: PMC4556040 DOI: 10.3389/fphys.2015.00238] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/07/2015] [Indexed: 12/20/2022] Open
Abstract
Heart failure (HF) is a serious debilitating condition with poor survival rates and an increasing level of prevalence. HF is associated with an increase in renal norepinephrine (NE) spillover, which is an independent predictor of mortality in HF patients. The excessive sympatho-excitation that is a hallmark of HF has long-term effects that contribute to disease progression. An increase in directly recorded renal sympathetic nerve activity (RSNA) has also been recorded in animal models of HF. This review will focus on the mechanisms controlling sympathetic nerve activity (SNA) to the kidney during normal conditions and alterations in these mechanisms during HF. In particular the roles of afferent reflexes and central mechanisms will be discussed.
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Affiliation(s)
- Rohit Ramchandra
- Department of Physiology, The University of Auckland Auckland, New Zealand
| | - Carolyn J Barrett
- Department of Physiology, The University of Auckland Auckland, New Zealand
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126
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Ahn B, Beharry AW, Frye GS, Judge AR, Ferreira LF. NAD(P)H oxidase subunit p47phox is elevated, and p47phox knockout prevents diaphragm contractile dysfunction in heart failure. Am J Physiol Lung Cell Mol Physiol 2015. [PMID: 26209274 DOI: 10.1152/ajplung.00176.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Patients with chronic heart failure (CHF) have dyspnea and exercise intolerance, which are caused in part by diaphragm abnormalities. Oxidants impair diaphragm contractile function, and CHF increases diaphragm oxidants. However, the specific source of oxidants and its relevance to diaphragm abnormalities in CHF is unclear. The p47(phox)-dependent Nox2 isoform of NAD(P)H oxidase is a putative source of diaphragm oxidants. Thus, we conducted our study with the goal of determining the effects of CHF on the diaphragm levels of Nox2 complex subunits and test the hypothesis that p47(phox) knockout prevents diaphragm contractile dysfunction elicited by CHF. CHF caused a two- to sixfold increase (P < 0.05) in diaphragm mRNA and protein levels of several Nox2 subunits, with p47(phox) being upregulated and hyperphosphorylated. CHF increased diaphragm extracellular oxidant emission in wild-type but not p47(phox) knockout mice. Diaphragm isometric force, shortening velocity, and peak power were decreased by 20-50% in CHF wild-type mice (P < 0.05), whereas p47(phox) knockout mice were protected from impairments in diaphragm contractile function elicited by CHF. Our experiments show that p47(phox) is upregulated and involved in the increased oxidants and contractile dysfunction in CHF diaphragm. These findings suggest that a p47(phox)-dependent NAD(P)H oxidase mediates the increase in diaphragm oxidants and contractile dysfunction in CHF.
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Affiliation(s)
- Bumsoo Ahn
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
| | - Adam W Beharry
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Gregory S Frye
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
| | - Andrew R Judge
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Leonardo F Ferreira
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
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127
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Ashley Z, Schwenke DO, Cragg PA. Hyperventilation in normoxia following myocardial infarction in rats: a shift in the set point of the hypoxic ventilatory response. Acta Physiol (Oxf) 2015; 214:415-25. [PMID: 25980319 DOI: 10.1111/apha.12527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/22/2015] [Accepted: 05/08/2015] [Indexed: 11/30/2022]
Abstract
AIM The peripheral chemoreflex is augmented in heart failure, and it may contribute to sympathoexcitation. This study aimed to investigate both the chemoreflex and the cardiac sympathetic nerve activity in the acute-stage post-myocardial infarction. METHODS Myocardial infarction was induced in male adult Sprague-Dawley rats by permanent ligation of the left anterior descending coronary artery. Within-animal repeated measure assessment of normoxic and hypoxic ventilation patterns was determined with whole-body plethysmography and compared to sham-operated controls. Cardiac function, morphology and cardiac sympathetic nerve activity were determined 14 days later. RESULTS Infarction induced increases in normoxic ventilation through increases in tidal volume within 3 days. At the same time points, the hypoxic ventilatory response to short durations (10 min) of hypoxia (8, 10 and 12% inspired O2 ) was blunted. At the end of the experiment (D14), increases in nerve activity, specifically through increased firing rate, and significant cardiac dysfunction (ejection fraction 43%) were observed in myocardial infarction (MI) group. CONCLUSIONS An augmentation of normoxic ventilation caused by myocardial infarction occurs before the amplification of the hypoxic ventilatory response. It occurs much earlier following myocardial injury than previously demonstrated and may have a role in initiating cardiac sympathoexcitation. The difference in the augmentation of hypoxic response between early and late stages post-myocardial infarction suggest that the initial change in the chemoreflex is an alteration to the operating point of chemoreflex.
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Affiliation(s)
- Z. Ashley
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - D. O. Schwenke
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - P. A. Cragg
- Department of Physiology; Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
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128
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Commentaries on Viewpoint: Precedence and autocracy in breathing control. J Appl Physiol (1985) 2015; 118:1557-9. [DOI: 10.1152/japplphysiol.00229.2015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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129
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Fukuda K, Kanazawa H, Aizawa Y, Ardell JL, Shivkumar K. Cardiac innervation and sudden cardiac death. Circ Res 2015; 116:2005-19. [PMID: 26044253 PMCID: PMC4465108 DOI: 10.1161/circresaha.116.304679] [Citation(s) in RCA: 260] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/11/2014] [Indexed: 12/14/2022]
Abstract
Afferent and efferent cardiac neurotransmission via the cardiac nerves intricately modulates nearly all physiological functions of the heart (chronotropy, dromotropy, lusitropy, and inotropy). Afferent information from the heart is transmitted to higher levels of the nervous system for processing (intrinsic cardiac nervous system, extracardiac-intrathoracic ganglia, spinal cord, brain stem, and higher centers), which ultimately results in efferent cardiomotor neural impulses (via the sympathetic and parasympathetic nerves). This system forms interacting feedback loops that provide physiological stability for maintaining normal rhythm and life-sustaining circulation. This system also ensures that there is fine-tuned regulation of sympathetic-parasympathetic balance in the heart under normal and stressed states in the short (beat to beat), intermediate (minutes to hours), and long term (days to years). This important neurovisceral/autonomic nervous system also plays a major role in the pathophysiology and progression of heart disease, including heart failure and arrhythmias leading to sudden cardiac death. Transdifferentiation of neurons in heart failure, functional denervation, cardiac and extracardiac neural remodeling has also been identified and characterized during the progression of disease. Recent advances in understanding the cellular and molecular processes governing innervation and the functional control of the myocardium in health and disease provide a rational mechanistic basis for the development of neuraxial therapies for preventing sudden cardiac death and other arrhythmias. Advances in cellular, molecular, and bioengineering realms have underscored the emergence of this area as an important avenue of scientific inquiry and therapeutic intervention.
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Affiliation(s)
- Keiichi Fukuda
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.).
| | - Hideaki Kanazawa
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Yoshiyasu Aizawa
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Jeffrey L Ardell
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Kalyanam Shivkumar
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.).
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130
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Marcus NJ, Pügge C, Mediratta J, Schiller AM, Del Rio R, Zucker IH, Schultz HD. Exercise training attenuates chemoreflex-mediated reductions of renal blood flow in heart failure. Am J Physiol Heart Circ Physiol 2015; 309:H259-66. [PMID: 26001414 DOI: 10.1152/ajpheart.00268.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 05/18/2015] [Indexed: 01/10/2023]
Abstract
In chronic heart failure (CHF), carotid body chemoreceptor (CBC) activity is increased and contributes to increased tonic and hypoxia-evoked elevation in renal sympathetic nerve activity (RSNA). Elevated RSNA and reduced renal perfusion may contribute to development of the cardio-renal syndrome in CHF. Exercise training (EXT) has been shown to abrogate CBC-mediated increases in RSNA in experimental heart failure; however, the effect of EXT on CBC control of renal blood flow (RBF) is undetermined. We hypothesized that CBCs contribute to tonic reductions in RBF in CHF, that stimulation of the CBC with hypoxia would result in exaggerated reductions in RBF, and that these responses would be attenuated with EXT. RBF was measured in CHF-sedentary (SED), CHF-EXT, CHF-carotid body denervation (CBD), and CHF-renal denervation (RDNX) groups. We measured RBF at rest and in response to hypoxia (FiO2 10%). All animals exhibited similar reductions in ejection fraction and fractional shortening as well as increases in ventricular systolic and diastolic volumes. Resting RBF was lower in CHF-SED (29 ± 2 ml/min) than in CHF-EXT animals (46 ± 2 ml/min, P < 0.05) or in CHF-CBD animals (42 ± 6 ml/min, P < 0.05). In CHF-SED, RBF decreased during hypoxia, and this was prevented in CHF-EXT animals. Both CBD and RDNX abolished the RBF response to hypoxia in CHF. Mean arterial pressure increased in response to hypoxia in CHF-SED, but was prevented by EXT, CBD, and RDNX. EXT is effective in attenuating chemoreflex-mediated tonic and hypoxia-evoked reductions in RBF in CHF.
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Affiliation(s)
- Noah J Marcus
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Carolin Pügge
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Jai Mediratta
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Alicia M Schiller
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Rodrigo Del Rio
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
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131
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Floras JS, Ponikowski P. The sympathetic/parasympathetic imbalance in heart failure with reduced ejection fraction. Eur Heart J 2015; 36:1974-82b. [PMID: 25975657 DOI: 10.1093/eurheartj/ehv087] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/06/2015] [Indexed: 12/20/2022] Open
Abstract
Cardiovascular autonomic imbalance, a cardinal phenotype of human heart failure, has adverse implications for symptoms during wakefulness and sleep; for cardiac, renal, and immune function; for exercise capacity; and for lifespan and mode of death. The objectives of this Clinical Review are to summarize current knowledge concerning mechanisms for disturbed parasympathetic and sympathetic circulatory control in heart failure with reduced ejection fraction and its clinical and prognostic implications; to demonstrate the patient-specific nature of abnormalities underlying this common phenotype; and to illustrate how such variation provides opportunities to improve or restore normal sympathetic/parasympathetic balance through personalized drug or device therapy.
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Affiliation(s)
- John S Floras
- University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Suite 1614, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5
| | - Piotr Ponikowski
- Department for Heart Disease, Medical University, Clinical Military Hospital, Wroclaw, Poland
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132
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Zucker IH, Schultz HD, Patel KP, Wang H. Modulation of angiotensin II signaling following exercise training in heart failure. Am J Physiol Heart Circ Physiol 2015; 308:H781-91. [PMID: 25681422 PMCID: PMC4398865 DOI: 10.1152/ajpheart.00026.2015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 02/04/2015] [Indexed: 02/07/2023]
Abstract
Sympathetic activation is a consistent finding in the chronic heart failure (CHF) state. Current therapy for CHF targets the renin-angiotensin II (ANG II) and adrenergic systems. Angiotensin converting enzyme (ACE) inhibitors and ANG II receptor blockers are standard treatments along with β-adrenergic blockade. However, the mortality and morbidity of this disease is still extremely high, even with good medical management. Exercise training (ExT) is currently being used in many centers as an adjunctive therapy for CHF. Clinical studies have shown that ExT is a safe, effective, and inexpensive way to improve quality of life, work capacity, and longevity in patients with CHF. This review discusses the potential neural interactions between ANG II and sympatho-excitation in CHF and the modulation of this interaction by ExT. We briefly review the current understanding of the modulation of the angiotensin type 1 receptor in sympatho-excitatory areas of the brain and in the periphery (i.e., in the carotid body and skeletal muscle). We discuss possible cellular mechanisms by which ExT may impact the sympatho-excitatory process by reducing oxidative stress, increasing nitric oxide. and reducing ANG II. We also discuss the potential role of ACE2 and Ang 1-7 in the sympathetic response to ExT. Fruitful areas of further investigation are the role and mechanisms by which pre-sympathetic neuronal metabolic activity in response to individual bouts of exercise regulate redox mechanisms and discharge at rest in CHF and other sympatho-excitatory states.
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Affiliation(s)
- Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Hanjun Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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133
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Fudim M, Groom KL, Laffer CL, Netterville JL, Robertson D, Elijovich F. Effects of carotid body tumor resection on the blood pressure of essential hypertensive patients. ACTA ACUST UNITED AC 2015; 9:435-42. [PMID: 26051925 DOI: 10.1016/j.jash.2015.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/02/2015] [Accepted: 03/13/2015] [Indexed: 11/17/2022]
Abstract
Removal of carotid body (CB) improves animal models of hypertension (HTN) and heart failure, via withdrawal of chemoreflex-induced sympathetic activation. Effect of CB tumor (CBT) resection on blood pressure (BP) in subjects with HTN is unknown. A retrospective analysis of 20 subjects with HTN (BP≥140/90 mmHg or anti-hypertensives use) out of 134 with CBT resection. Short-term (30 days from surgery) and long-term (slope of regressions on time over the entire follow-up) changes in BP and heart rate were adjusted for covariates (interval between readings, total follow-up, number of readings and changes in therapy). Age and duration of HTN were 56±4 and 9±5 years. Adjusted short-term decreases in systolic (SBP: -9.9±3.1, p<0.001) and pulse pressures (PP: -7.9±2.7, p<0.002) were significant and correlated with their respective long-term changes (SBP: r=0.47, p=0.047; PP: r=0.54, p=0.019). There was a strong relationship between adjusted short-term changes in SBP and PP (r=0.64, p<0.004). Six (50% of responders or 33% of the total) had short-term falls of SBP ≥10 mmHg and of PP ≥ 5 mmHg. First study to show that unilateral CBT resection is associated with sustained reduction of BP in hypertensive patients. Targeted CB chemoreflex removal could play a role in the therapy of human HTN.
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Affiliation(s)
- Marat Fudim
- Internal Medicine Department, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Kelly L Groom
- Division of Head and Neck Oncologic Surgery, Department of Otolaryngology, Head and Neck Surgery, Vanderbilt Bill Wilkerson Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Cheryl L Laffer
- Division of Clinical Pharmacology, Department of Medicine, The Vanderbilt Comprehensive Hypertension Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James L Netterville
- Division of Head and Neck Oncologic Surgery, Department of Otolaryngology, Head and Neck Surgery, Vanderbilt Bill Wilkerson Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David Robertson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Autonomic Dysfunction Center, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Fernando Elijovich
- Division of Clinical Pharmacology, Department of Medicine, The Vanderbilt Comprehensive Hypertension Center, Vanderbilt University School of Medicine, Nashville, TN, USA
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135
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Edgell H, McMurtry MS, Haykowsky MJ, Paterson I, Ezekowitz JA, Dyck JRB, Stickland MK. Peripheral chemoreceptor control of cardiovascular function at rest and during exercise in heart failure patients. J Appl Physiol (1985) 2015; 118:839-48. [PMID: 25614600 DOI: 10.1152/japplphysiol.00898.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 01/20/2015] [Indexed: 01/01/2023] Open
Abstract
Peripheral chemoreceptor activity/sensitivity is enhanced in chronic heart failure (HF), and sensitivity is linked to greater mortality. This study aimed to determine the role of the peripheral chemoreceptor in cardiovascular control at rest and during exercise in HF patients and controls. Clinically stable HF patients (n = 11; ejection fraction: 39 ± 5%) and risk-matched controls (n = 10; ejection fraction: 65 ± 2%) performed randomized trials with or without dopamine infusion (2 μg·min(-1)·kg(-1)) at rest and during 40% maximal voluntary contraction handgrip (HG) exercise, and a resting trial of 2 min of inspired 100% oxygen. Both dopamine and hyperoxia were used to inhibit the peripheral chemoreceptor. At rest in HF patients, dopamine decreased ventilation (P = 0.02), decreased total peripheral resistance index (P = 0.003), and increased cardiac and stroke indexes (P ≤ 0.01), yet there was no effect of dopamine on these variables in controls (P ≥ 0.7). Hyperoxia lowered ventilation in HF (P = 0.01), but not in controls (P = 0.9), indicating suppression of the peripheral chemoreceptors in HF. However, no decrease of total peripheral resistance index was observed in HF. As expected, HG increased heart rate, ventilation, and brachial conductance of the nonexercising arm in controls and HF patients. During dopamine infusion, there were no changes in mean arterial pressure, heart rate, or ventilation responses to HG in either group (P ≥ 0.26); however, brachial conductance increased with dopamine in the control group (P = 0.004), but decreased in HF (P = 0.02). Our findings indicate that the peripheral chemoreceptor contributes to cardiovascular control at rest in HF patients and during exercise in risk-matched controls.
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Affiliation(s)
- Heather Edgell
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - M Sean McMurtry
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Mark J Haykowsky
- Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada; and
| | - Ian Paterson
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Justin A Ezekowitz
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Michael K Stickland
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; G.F. MacDonald Centre for Lung Health (Covenant Health), Edmonton, Alberta, Canada
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136
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Schultz HD, Marcus NJ, Del Rio R. Mechanisms of carotid body chemoreflex dysfunction during heart failure. Exp Physiol 2015; 100:124-9. [PMID: 25398713 DOI: 10.1113/expphysiol.2014.079517] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/03/2014] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? Carotid body chemoreceptor activity is tonically elevated in heart failure and contributes to morbidity due to the reflex activation of sympathetic nerve activity and destabilization of breathing. The potential causes for the enhanced chemoreceptor activation in heart failure are discussed. What advances does it highlight? The role of a chronic reduction in blood flow to the carotid body due to cardiac failure and its impact on signalling pathways in the carotid body is discussed. Recent advances have attracted interest in the potential for carotid body (CB) ablation or desensitization as an effective strategy for clinical treatment and management of cardiorespiratory diseases, including hypertension, heart failure, diabetes mellitus, metabolic syndrome and renal failure. These disease states have in common sympathetic overactivity, which plays an important role in the development and progression of the disease and is often associated with breathing dysregulation, which in turn is likely to mediate or aggravate the autonomic imbalance. Evidence from both chronic heart failure (CHF) patients and animal models indicates that the CB chemoreflex is enhanced in CHF and contributes to the tonic elevation in sympathetic activity and the development of periodic breathing associated with the disease. Although this maladaptive change is likely to derive from altered function at all levels of the reflex arc, a tonic increase in afferent activity from CB glomus cells is likely to be a main driving force. This report focuses on our understanding of mechanisms that alter CB function in CHF and their potential translational impact on treatment of CHF.
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Affiliation(s)
- Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
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137
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Prabhakhar NR, Joyner MJ. Tasting arterial blood: what do the carotid chemoreceptors sense? Front Physiol 2015; 5:524. [PMID: 25642193 PMCID: PMC4294136 DOI: 10.3389/fphys.2014.00524] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/20/2014] [Indexed: 01/16/2023] Open
Abstract
The carotid bodies are sensory organs that detect the chemical composition of the arterial blood. The carotid body sensory activity increases in response to arterial hypoxemia and the ensuing chemoreflex regulates vital homeostatic functions. Recent studies suggest that the carotid bodies might also sense arterial blood glucose and circulating insulin levels. This review focuses on how the carotid bodies sense O2, glucose, and insulin and some potential implications of these sensory functions on physiological regulation and in pathophysiological conditions. Emerging evidence suggests that carbon monoxide (CO)-regulated hydrogen sulfide (H2S), stemming from hypoxia, depolarizes type I cells by inhibiting certain K+ channels, facilitates voltage-gated Ca2+ influx leading to sensory excitation of the carotid body. Elevated CO and decreased H2S renders the carotid bodies insensitive to hypoxia resulting in attenuated ventilatory adaptations to high altitude hypoxia, whereas reduced CO and high H2S result in hypersensitivity of the carotid bodies to hypoxia and hypertension. Acute hypoglycemia augments the carotid body responses to hypoxia but that a prolonged lack of glucose in the carotid bodies can lead to a failure to sense hypoxia. Emerging evidence also indicates that carotid bodies might sense insulin directly independent of its effect on glucose, linking the carotid bodies to the pathophysiological consequences of the metabolic syndrome. How glucose and insulin interact with the CO-H2S signaling is an area of ongoing study.
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Affiliation(s)
- Nanduri R Prabhakhar
- Institute for Integrative Physiology, Center for Systems Biology of O2 Sensing, The University of Chicago Chicago, IL, USA
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138
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Del Rio R, Andrade DC, Marcus NJ, Schultz HD. Selective carotid body ablation in experimental heart failure: a new therapeutic tool to improve cardiorespiratory control. Exp Physiol 2015; 100:136-42. [PMID: 25398714 DOI: 10.1113/expphysiol.2014.079566] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/10/2014] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review summarizes the physiological role played by the carotid body in the autonomic dysregulation and breathing disturbances during the progression of chronic heart failure and the therapeutic potential of carotid body ablation to control cardiorespiratory imbalance and improve survival in heart failure. What advances does it highlight? Carotid body ablation markedly improves breathing stability and normalizes autonomic function in chronic heart failure. More importantly, if carotid body ablation is performed early during the progression of the disease it significantly improves animal survival. Chronic heart failure (CHF) is a leading medical problem worldwide. Common hallmarks of CHF include autonomic imbalance and breathing disorders, both of which are closely related to the progression of the disease and strongly predict mortality in CHF patients. The role played by the carotid body (CB) chemoreceptors in the progression of CHF has received attention because enhanced carotid chemoreflex drive is thought to contribute to autonomic dysfunction, abnormal breathing patterns and increased mortality in CHF. Therefore, therapeutic tools intended to normalize CB-mediated chemoreflex drive could have the potential to improve quality of life and decrease mortality of CHF patients. In experimental CHF, an enhancement of the CB chemoreflex drive, elevated sympathetic outflow, increased resting breathing variability, increased incidence of apnoea and desensitization of the baroreflex have been shown. Notably, selective elimination of the CB reduced central presympathetic neuronal activation, normalized sympathetic outflow and baroreflex sensitivity and stabilized breathing function in CHF. More remarkably, CB ablation has been shown to be a valuable therapeutic tool that significantly reduced aberrant cardiac remodelling, improved left ventriclular ejection fraction and reduced cardiac arrhythmogenesis. Most importantly, animals with CHF that underwent CB ablation showed a marked improvement in survival rate. Interestingly, a case report from a heart failure patient in whom unilateral CB ablation was performed showed promising results, with significant improvement in autonomic balance and breathing variability. Together, the CHF data from experimental animals as well as humans unveil a major role for the CB chemoreceptors in the progression of heart failure and support the notion that CB ablation could represent a novel therapeutic strategy to reduce cardiorespiratory dysfunction and improve survival during heart failure.
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Affiliation(s)
- Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile, Santiago, Chile
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139
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Role of the Carotid Body Chemoreflex in the Pathophysiology of Heart Failure: A Perspective from Animal Studies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 860:167-85. [PMID: 26303479 DOI: 10.1007/978-3-319-18440-1_19] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The treatment and management of chronic heart failure (CHF) remains an important focus for new and more effective clinical strategies. This important goal, however, is dependent upon advancing our understanding of the underlying pathophysiology. In CHF, sympathetic overactivity plays an important role in the development and progression of the cardiac and renal dysfunction and is often associated with breathing dysregulation, which in turn likely mediates or aggravates the autonomic imbalance. In this review we will summarize evidence that in CHF, the elevation in sympathetic activity and breathing instability that ultimately lead to cardiac and renal failure are driven, at least in part, by maladaptive activation of the carotid body (CB) chemoreflex. This maladaptive change derives from a tonic increase in CB afferent activity. We will focus our discussion on an understanding of mechanisms that alter CB afferent activity in CHF and its consequence on reflex control of autonomic, respiratory, renal, and cardiac function in animal models of CHF. We will also discuss the potential translational impact of targeting the CB in the treatment of CHF in humans, with relevance to other cardio-respiratory diseases.
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140
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Iturriaga R, Andrade DC, Del Rio R. Enhanced carotid body chemosensory activity and the cardiovascular alterations induced by intermittent hypoxia. Front Physiol 2014; 5:468. [PMID: 25520668 PMCID: PMC4251310 DOI: 10.3389/fphys.2014.00468] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/14/2014] [Indexed: 02/03/2023] Open
Abstract
The carotid body (CB) plays a main role in the maintenance of the oxygen homeostasis. The hypoxic stimulation of the CB increases the chemosensory discharge, which in turn elicits reflex sympathetic, cardiovascular, and ventilatory adjustments. An exacerbate carotid chemosensory activity has been associated with human sympathetic-mediated diseases such as hypertension, insulin resistance, heart failure, and obstructive sleep apnea (OSA). Indeed, the CB chemosensory discharge becomes tonically hypereactive in experimental models of OSA and heart failure. Chronic intermittent hypoxia (CIH), a main feature of OSA, enhances CB chemosensory baseline discharges in normoxia and in response to hypoxia, inducing sympathetic overactivity and hypertension. Oxidative stress, increased levels of ET-1, Angiotensin II and pro-inflammatory cytokines, along with a reduced production of NO in the CB, have been associated with the enhanced carotid chemosensory activity. In this review, we will discuss new evidence supporting a main role for the CB chemoreceptor in the autonomic and cardiorespiratory alterations induced by intermittent hypoxia, as well as the molecular mechanisms involved in the CB chemosensory potentiation.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - David C Andrade
- Laboratorio de Neurobiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
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141
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Marcus NJ, Del Rio R, Schultz HD. Central role of carotid body chemoreceptors in disordered breathing and cardiorenal dysfunction in chronic heart failure. Front Physiol 2014; 5:438. [PMID: 25505417 PMCID: PMC4241833 DOI: 10.3389/fphys.2014.00438] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 10/27/2014] [Indexed: 11/13/2022] Open
Abstract
Oscillatory breathing (OB) patterns are observed in pre-term infants, patients with cardio-renal impairment, and in otherwise healthy humans exposed to high altitude. Enhanced carotid body (CB) chemoreflex sensitivity is common to all of these populations and is thought to contribute to these abnormal patterns by destabilizing the respiratory control system. OB patterns in chronic heart failure (CHF) patients are associated with greater levels of tonic and chemoreflex-evoked sympathetic nerve activity (SNA), which is associated with greater morbidity and poor prognosis. Enhanced chemoreflex drive may contribute to tonic elevations in SNA by strengthening the relationship between respiratory and sympathetic neural outflow. Elimination of CB afferents in experimental models of CHF has been shown to reduce OB, respiratory-sympathetic coupling, and renal SNA, and to improve autonomic balance in the heart. The CB chemoreceptors may play an important role in progression of CHF by contributing to respiratory instability and OB, which in turn further exacerbates tonic and chemoreflex-evoked increases in SNA to the heart and kidney.
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Affiliation(s)
- Noah J Marcus
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
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Abstract
Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
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143
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Fung ML. The role of local renin-angiotensin system in arterial chemoreceptors in sleep-breathing disorders. Front Physiol 2014; 5:336. [PMID: 25249981 PMCID: PMC4155775 DOI: 10.3389/fphys.2014.00336] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/15/2014] [Indexed: 11/23/2022] Open
Abstract
The renin-angiotensin system (RAS) plays pivotal roles in the regulation of cardiovascular and renal functions to maintain the fluid and electrolyte homeostasis. Experimental studies have demonstrated a locally expressed RAS in the carotid body, which is functional significant in the effect of angiotensin peptides on the regulation of the activity of peripheral chemoreceptors and the chemoreflex. The physiological and pathophysiological implications of the RAS in the carotid body have been proposed upon recent studies showing a significant upregulation of the RAS expression under hypoxic conditions relevant to altitude acclimation and sleep apnea and also in animal model of heart failure. Specifically, the increased expression of angiotensinogen, angiotensin-converting enzyme and angiotensin AT1 receptors plays significant roles in the augmented carotid chemoreceptor activity and inflammation of the carotid body. This review aims to summarize these results with highlights on the pathophysiological function of the RAS under hypoxic conditions. It is concluded that the maladaptive changes of the RAS in the carotid body plays a pathogenic role in sleep apnea and heart failure, which could potentially be a therapeutic target for the treatment of the pathophysiological consequence of sleep apnea.
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Affiliation(s)
- Man Lung Fung
- Department of Physiology, University of Hong Kong Pokfulam, Hong Kong
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144
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Schultz HD. The arterial chemoreflex and cardiac stress in heart failure: nothing to be sheepish about. Exp Physiol 2014; 99:1029-30. [PMID: 25085916 DOI: 10.1113/expphysiol.2014.081299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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145
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Abstract
We review the substantial recent progress made in understanding the underlying mechanisms controlling breathing and the applicability of these findings to selected human diseases. Emphasis is placed on the sites of central respiratory rhythm and pattern generation as well as newly described functions of the carotid chemoreceptors, the integrative nature of the central chemoreceptors, and the interaction between peripheral and central chemoreception. Recent findings that support critical contributions from cortical central command and muscle afferent feedback to exercise hyperpnoea are also reviewed. These basic principles, and the evidence supporting chemoreceptor and ventilatory control system plasticity during and following constant and intermittent hypoxaemia and stagnant hypoxia, are applied to: 1) the pathogenesis, consequences and treatment of obstructive sleep apnoea; and 2) exercise hyperpnoea and its control and limitations with ageing, chronic obstructive pulmonary disease and congestive heart failure.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Curtis A Smith
- John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, WI, USA
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146
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Xing DT, May CN, Booth LC, Ramchandra R. Tonic arterial chemoreceptor activity contributes to cardiac sympathetic activation in mild ovine heart failure. Exp Physiol 2014; 99:1031-41. [PMID: 24928955 DOI: 10.1113/expphysiol.2014.079491] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Heart failure (HF) is associated with a large increase in cardiac sympathetic nerve activity (CSNA), which has detrimental effects on the heart and promotes arrhythmias and sudden death. There is increasing evidence that arterial chemoreceptor activation plays an important role in stimulating renal sympathetic nerve activity (RSNA) and muscle sympathetic nerve activity in HF. Given that sympathetic nerve activity to individual organs is differentially controlled, we investigated whether tonic arterial chemoreceptor activation contributes to the increased CSNA in HF. We recorded CSNA and RSNA in conscious normal sheep and in sheep with mild HF induced by rapid ventricular pacing (ejection fraction <40%). Tonic arterial chemoreceptor function was evaluated by supplementing room air with 100% intranasal oxygen (2-3 l min(-1)) for 20 min, thereby deactivating chemoreceptors. The effects of hyperoxia on resting levels and baroreflex control of heart rate, CSNA and RSNA were determined. In HF, chemoreceptor deactivation induced by hyperoxia significantly reduced CSNA [90 ± 2 versus 75 ± 5 bursts (100 heart beats)(-1), P < 0.05, n = 10; room air versus hyperoxia] and heart rate (96 ± 4 versus 85 ± 4 beats min(-1), P < 0.001, n = 12). There was no change in RSNA burst incidence [93 ± 4 versus 92 ± 4 bursts (100 heart beats)(-1), n = 7], although due to the bradycardia the RSNA burst frequency was decreased (90 ± 8 versus 77 ± 7 bursts min(-1), P < 0.001). In normal sheep, chemoreceptor deactivation reduced heart rate without a significant effect on CSNA or RSNA. In summary, deactivation of peripheral chemoreceptors during HF reduced the elevated levels of CSNA, indicating that tonic arterial chemoreceptor activation plays a critical role in stimulating the elevated CSNA in HF.
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Affiliation(s)
- Daniel T Xing
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia
| | - Clive N May
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia
| | - Lindsea C Booth
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia
| | - Rohit Ramchandra
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia
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147
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Giannoni A, Passino C, Mirizzi G, Del Franco A, Aimo A, Emdin M. Treating chemoreflex in heart failure: modulation or demolition? J Physiol 2014; 592:1903-4. [PMID: 24737899 DOI: 10.1113/jphysiol.2014.272740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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148
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Marcus NJ, Del Rio R, Schultz HD. Reply from Noah J. Marcus, Rodrigo Del Rio and Harold D. Schultz. J Physiol 2014; 592:1905-6. [PMID: 24737900 DOI: 10.1113/jphysiol.2014.273565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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149
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Nobrega ACL, O'Leary D, Silva BM, Marongiu E, Piepoli MF, Crisafulli A. Neural regulation of cardiovascular response to exercise: role of central command and peripheral afferents. BIOMED RESEARCH INTERNATIONAL 2014; 2014:478965. [PMID: 24818143 PMCID: PMC4000959 DOI: 10.1155/2014/478965] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/04/2014] [Indexed: 12/12/2022]
Abstract
During dynamic exercise, mechanisms controlling the cardiovascular apparatus operate to provide adequate oxygen to fulfill metabolic demand of exercising muscles and to guarantee metabolic end-products washout. Moreover, arterial blood pressure is regulated to maintain adequate perfusion of the vital organs without excessive pressure variations. The autonomic nervous system adjustments are characterized by a parasympathetic withdrawal and a sympathetic activation. In this review, we briefly summarize neural reflexes operating during dynamic exercise. The main focus of the present review will be on the central command, the arterial baroreflex and chemoreflex, and the exercise pressure reflex. The regulation and integration of these reflexes operating during dynamic exercise and their possible role in the pathophysiology of some cardiovascular diseases are also discussed.
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Affiliation(s)
- Antonio C. L. Nobrega
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, RJ, Brazil
| | - Donal O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Bruno Moreira Silva
- Section of Exercise Physiology, Department of Physiology, Federal University of São Paulo, SP, Brazil
| | - Elisabetta Marongiu
- Sports Physiology laboratory Lab., Department of Medical Sciences, University of Cagliari, Italy
| | - Massimo F. Piepoli
- Heart Failure Unit, Cardiac Department, Guglielmo da Saliceto Polichirurgico Hospital, Piacenza, Italy
| | - Antonio Crisafulli
- Sports Physiology laboratory Lab., Department of Medical Sciences, University of Cagliari, Italy
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150
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Johnson BD, Limberg JK. Is carotid body denervation the silver bullet for heart failure? J Physiol 2014; 592:1179-80. [PMID: 24634019 DOI: 10.1113/jphysiol.2013.270181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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