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Bizanti A, Zhang Y, Toledo Z, Bendowski KT, Harden SW, Mistareehi A, Chen J, Gozal D, Heal M, Christie R, Hunter PJ, Paton JFR, Cheng ZJ. Chronic intermittent hypoxia remodels catecholaminergic nerve innervation in mouse atria. J Physiol 2024; 602:49-71. [PMID: 38156943 PMCID: PMC10842556 DOI: 10.1113/jp284961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 10/04/2023] [Indexed: 01/03/2024] Open
Abstract
Chronic intermittent hypoxia (CIH, a model for sleep apnoea) is a major risk factor for several cardiovascular diseases. Autonomic imbalance (sympathetic overactivity and parasympathetic withdrawal) has emerged as a causal contributor of CIH-induced cardiovascular disease. Previously, we showed that CIH remodels the parasympathetic pathway. However, whether CIH induces remodelling of the cardiac sympathetic innervation remains unknown. Mice (male, C57BL/6J, 2-3 months) were exposed to either room air (RA, 21% O2 ) or CIH (alternating 21% and 5.7% O2 , every 6 min, 10 h day-1 ) for 8-10 weeks. Flat-mounts of their left and right atria were immunohistochemically labelled for tyrosine hydroxylase (TH, a sympathetic marker). Using a confocal microscope (or fluorescence microscope) and Neurlocudia 360 digitization and tracing system, we scanned both the left and right atria and quantitatively analysed the sympathetic axon density in both groups. The segmentation data was mapped onto a 3D mouse heart scaffold. Our findings indicated that CIH significantly remodelled the TH immunoreactive (-IR) innervation of the atria by increasing its density at the sinoatrial node, the auricles and the major veins attached to the atria (P < 0.05, n = 7). Additionally, CIH increased the branching points of TH-IR axons and decreased the distance between varicosities. Abnormal patterns of TH-IR axons around intrinsic cardiac ganglia were also found following CIH. We postulate that the increased sympathetic innervation may further amplify the effects of enhanced CIH-induced central sympathetic drive to the heart. Our work provides an anatomical foundation for the understanding of CIH-induced autonomic imbalance. KEY POINTS: Chronic intermittent hypoxia (CIH, a model for sleep apnoea) causes sympathetic overactivity, cardiovascular remodelling and hypertension. We determined the effect of CIH on sympathetic innervation of the mouse atria. In vivo CIH for 8-10 weeks resulted in an aberrant axonal pattern around the principal neurons within intrinsic cardiac ganglia and an increase in the density, branching point, tortuosity of catecholaminergic axons and atrial wall thickness. Utilizing mapping tool available from NIH (SPARC) Program, the topographical distribution of the catecholaminergic innervation of the atria were integrated into a novel 3D heart scaffold for precise anatomical distribution and holistic quantitative comparison between normal and CIH mice. This work provides a unique neuroanatomical understanding of the pathophysiology of CIH-induced autonomic remodelling.
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Affiliation(s)
- Ariege Bizanti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Yuanyuan Zhang
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Zulema Toledo
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Kohlton T Bendowski
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Scott W Harden
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Anas Mistareehi
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - David Gozal
- Joan C. Edwards School of medicine, Marshall University, Huntington, WV, USA
| | - Maci Heal
- MBF Bioscience, Williston, Vermont, USA
| | - Richard Christie
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peter J Hunter
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Julian F R Paton
- Department Physiology, Manaaki Manawa-the Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Zixi Jack Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
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Bizanti A, Zhang Y, Harden SW, Chen J, Hoover DB, Gozal D, Shivkumar K, Cheng ZJ. Catecholaminergic axon innervation and morphology in flat-mounts of atria and ventricles of mice. J Comp Neurol 2023; 531:596-617. [PMID: 36591925 PMCID: PMC10499115 DOI: 10.1002/cne.25444] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 01/03/2023]
Abstract
Sympathetic efferent axons regulate cardiac functions. However, the topographical distribution and morphology of cardiac sympathetic efferent axons remain insufficiently characterized due to the technical challenges involved in immunohistochemical labeling of the thick walls of the whole heart. In this study, flat-mounts of the left and right atria and ventricles of FVB mice were immunolabeled for tyrosine hydroxylase (TH), a marker of sympathetic nerves. Atrial and ventricular flat-mounts were scanned using a confocal microscope to construct montages. We found (1) In the atria: A few large TH-immunoreactive (IR) axon bundles entered both atria, branched into small bundles and then single axons that eventually formed very dense terminal networks in the epicardium, myocardium and inlet regions of great vessels to the atria. Varicose TH-IR axons formed close contact with cardiomyocytes, vessels, and adipocytes. Multiple intrinsic cardiac ganglia (ICG) were identified in the epicardium of both atria, and a subpopulation of the neurons in the ICG were TH-IR. Most TH-IR axons in bundles traveled through ICG before forming dense varicose terminal networks in cardiomyocytes. We did not observe varicose TH-IR terminals encircling ICG neurons. (2) In the left and right ventricles and interventricular septum: TH-IR axons formed dense terminal networks in the epicardium, myocardium, and vasculature. Collectively, TH labeling is achievable in flat-mounts of thick cardiac walls, enabling detailed mapping of catecholaminergic axons and terminal structures in the whole heart at single-cell/axon/varicosity scale. This approach provides a foundation for future quantification of the topographical organization of the cardiac sympathetic innervation in different pathological conditions.
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Affiliation(s)
- Ariege Bizanti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Yuanyuan Zhang
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Scott W Harden
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Donald B Hoover
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee, USA
| | - David Gozal
- Department of Child Health and Child Health Research Institute, and Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Kalyanam Shivkumar
- Department of Medicine, Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California, Los Angeles, California, USA
| | - Zixi Jack Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
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Kay MW, Jain V, Panjrath G, Mendelowitz D. Targeting Parasympathetic Activity to Improve Autonomic Tone and Clinical Outcomes. Physiology (Bethesda) 2022; 37:39-45. [PMID: 34486396 PMCID: PMC8742722 DOI: 10.1152/physiol.00023.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In this review we will briefly summarize the evidence that autonomic imbalance, more specifically reduced parasympathetic activity to the heart, generates and/or maintains many cardiorespiratory diseases and will discuss mechanisms and sites, from myocytes to the brain, that are potential translational targets for restoring parasympathetic activity and improving cardiorespiratory health.
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Affiliation(s)
- Matthew W. Kay
- 1Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | - Vivek Jain
- 2Division of Pulmonary Medicine, Department of Medicine, George Washington University, Washington, District of Columbia
| | - Gurusher Panjrath
- 3Division of Cardiology, Department of Medicine, George Washington University, Washington, District of Columbia
| | - David Mendelowitz
- 4Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
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Castro-Grattoni AL, Suarez-Giron M, Benitez I, Tecchia L, Torres M, Almendros I, Farre R, Targa A, Montserrat JM, Dalmases M, Barbé F, Gozal D, Sánchez-de-la-Torre M. The effect of chronic intermittent hypoxia in cardiovascular gene expression is modulated by age in a mice model of sleep apnea. Sleep 2021; 44:6071377. [PMID: 33417710 DOI: 10.1093/sleep/zsaa293] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/18/2020] [Indexed: 12/13/2022] Open
Abstract
STUDY OBJECTIVES Chronic intermittent hypoxia (CIH) is a major determinant in obstructive sleep apnea cardiovascular morbidity and this effect is influenced by age. The objective of the present study was to assess the differential molecular mechanisms at gene-level expression involved in the cardiovascular remodeling induced by CIH according to chronological age. METHODS Two- and 18-month-old mice (N = 8 each) were subjected to CIH or normoxia for 8 weeks. Total messenger RNA (mRNA) was extracted from left ventricle myocardium and aortic arch, and gene expression of 46 intermediaries of aging, oxidative stress, and inflammation was measured by quantitative real-time polymerase chain reaction. RESULTS Cardiac gene expression of Nrf2 (2.05-fold increase, p < 0.001), Sod2 (1.9-fold increase, p = 0.035), Igf1r (1.4-fold increase, p = 0.028), Mtor (1.8-fold increase, p = 0.06), Foxo3 (1.5-fold increase, p = 0.020), Sirt4, Sirt6, and Sirt7 (1.3-fold increase, p = 0.012; 1.1-fold change, p = 0.031; 1.3-fold change, p = 0.029) was increased after CIH in young mice, but not in old mice. In aortic tissue, endothelial isoform of nitric oxide synthase was reduced in young mice (p < 0.001), Nrf2 was reduced in 80% (p < 0.001) in young mice and 45% (p = 0.07) in old mice, as its downstream antioxidant target Sod2 (82% reduced, p < 0.001). IL33. CONCLUSIONS CIH effect in gene expression is organ-dependent, and is modulated by age. CIH increased transcriptional expression of genes involved in cardioprotection and cell survival in young, but not in old mice. In aortic tissue, CIH reduced gene expression related to an antioxidant response in both young and old mice, suggesting vascular oxidative stress and a proaging process.
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Affiliation(s)
- Anabel L Castro-Grattoni
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain.,Department of Child Health, University of Missouri, School of Medicine, Columbia, MO, USA
| | | | - Ivan Benitez
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain
| | - Lourdes Tecchia
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain
| | - Marta Torres
- Agency for Health Quality and Assessment of Catalonia (AQuAS), Barcelona - CIBER de Enfermedades Respiratorias - CIBER de Epidemiología y Salud Pública, Madrid, Spain
| | - Isaac Almendros
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Ramon Farre
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Adriano Targa
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain
| | - Josep M Montserrat
- Laboratori del son, Servei de Pneumologia, Hospital Clínic, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Mireia Dalmases
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Ferran Barbé
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - David Gozal
- Department of Child Health, University of Missouri, School of Medicine, Columbia, MO, USA
| | - Manuel Sánchez-de-la-Torre
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, IRB Lleida, University of Lleida, Lleida, Catalonia, Spain.,Group of Precision Medicine in Chronic Diseases, Hospital Arnau de Vilanova-Santa Maria, IRB Lleida, Lleida, Spain
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5
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Chen J, Gu H, Wurster RD, Cheng ZJ. The protective role of SOD1 overexpression in central mediation of bradycardia following chronic intermittent hypoxia in mice. Am J Physiol Regul Integr Comp Physiol 2021; 320:R317-R330. [PMID: 33296277 PMCID: PMC7988771 DOI: 10.1152/ajpregu.00147.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/27/2020] [Accepted: 12/03/2020] [Indexed: 01/07/2023]
Abstract
Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder that is associated with many cardiovascular complications. Similar to OSA, chronic intermittent hypoxia (CIH) (a model for OSA) leads to oxidative stress and impairs baroreflex control of the heart rate (HR) in rodents. The baroreflex arc includes the aortic depressor nerve (ADN), vagal efferent, and central neurons. In this study, we used mice as a model to examine the effects of CIH on baroreflex sensitivity, aortic baroreceptor afferents, and central and vagal efferent components of the baroreflex circuitry. Furthermore, we tested whether human Cu/Zn Superoxide Dismutase (SOD1) overexpression in transgenic mice offers protection against CIH-induced deficit of the baroreflex arc. Wild-type C57BL/6J and SOD1 mice were exposed to room air (RA) or CIH and were then anesthetized, ventilated, and catheterized for measurement of mean arterial pressure (MAP) and HR. Compared with wild-type RA control, CIH impaired baroreflex sensitivity but increased maximum baroreceptor gain and bradycardic response to vagal efferent stimulation. Additionally, CIH reduced the bradycardic response to ADN stimulation, indicating a diminished central regulation of bradycardia. Interestingly, SOD1 overexpression prevented CIH-induced attenuation of HR responses to ADN stimulation and preserved HR responses to vagal efferent stimulation in transgenic mice. We suggest that CIH decreased central mediation of the baroreflex and SOD1 overexpression may prevent the CIH-induced central deficit.
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Affiliation(s)
- Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida
| | - He Gu
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida
| | - Robert D Wurster
- Department of Cellular and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood, Illinois
| | - Zixi Jack Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida
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Alzahrani AA, Cao LL, Aldossary HS, Nathanael D, Fu J, Ray CJ, Brain KL, Kumar P, Coney AM, Holmes AP. β-Adrenoceptor blockade prevents carotid body hyperactivity and elevated vascular sympathetic nerve density induced by chronic intermittent hypoxia. Pflugers Arch 2021; 473:37-51. [PMID: 33210151 PMCID: PMC7782391 DOI: 10.1007/s00424-020-02492-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/26/2020] [Accepted: 11/06/2020] [Indexed: 12/17/2022]
Abstract
Carotid body (CB) hyperactivity promotes hypertension in response to chronic intermittent hypoxia (CIH). The plasma concentration of adrenaline is reported to be elevated in CIH and our previous work suggests that adrenaline directly activates the CB. However, a role for chronic adrenergic stimulation in mediating CB hyperactivity is currently unknown. This study evaluated whether beta-blocker treatment with propranolol (Prop) prevented the development of CB hyperactivity, vascular sympathetic nerve growth and hypertension caused by CIH. Adult male Wistar rats were assigned into 1 of 4 groups: Control (N), N + Prop, CIH and CIH + Prop. The CIH paradigm consisted of 8 cycles h-1, 8 h day-1, for 3 weeks. Propranolol was administered via drinking water to achieve a dose of 40 mg kg-1 day-1. Immunohistochemistry revealed the presence of both β1 and β2-adrenoceptor subtypes on the CB type I cell. CIH caused a 2-3-fold elevation in basal CB single-fibre chemoafferent activity and this was prevented by chronic propranolol treatment. Chemoafferent responses to hypoxia and mitochondrial inhibitors were attenuated by propranolol, an effect that was greater in CIH animals. Propranolol decreased respiratory frequency in normoxia and hypoxia in N and CIH. Propranolol also abolished the CIH mediated increase in vascular sympathetic nerve density. Arterial blood pressure was reduced in propranolol groups during hypoxia. Propranolol exaggerated the fall in blood pressure in most (6/7) CIH animals during hypoxia, suggestive of reduced sympathetic tone. These findings therefore identify new roles for β-adrenergic stimulation in evoking CB hyperactivity, sympathetic vascular hyperinnervation and altered blood pressure control in response to CIH.
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Affiliation(s)
- Abdulaziz A Alzahrani
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Respiratory Care Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Lily L Cao
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Hayyaf S Aldossary
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- College of Medicine, Basic Medical Sciences, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Demitris Nathanael
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Jiarong Fu
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Clare J Ray
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Keith L Brain
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Prem Kumar
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Andrew M Coney
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Andrew P Holmes
- Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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Dyavanapalli J. Novel approaches to restore parasympathetic activity to the heart in cardiorespiratory diseases. Am J Physiol Heart Circ Physiol 2020; 319:H1153-H1161. [PMID: 33035444 DOI: 10.1152/ajpheart.00398.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neural control of the heart is regulated by sympathetic and parasympathetic divisions of the autonomic nervous system, both opposing each other to maintain cardiac homeostasis via regulating heart rate, conduction velocity, force of contraction, and coronary blood flow. Sympathetic hyperactivity and diminished parasympathetic activity are the characteristic features of many cardiovascular disease states including hypertension, myocardial ischemia, and arrhythmias that result in heart failure. Restoring parasympathetic activity to the heart has recently been identified as the promising approach to treat such conditions. However, approaches that used vagal nerve stimulation have been shown to be unsuccessful in heart failure. This review focuses on novel chemogenetic approaches used to identify the cardioprotective nature of activating neural points along the vagal pathway (both central and peripheral) while being selectively therapeutic in heart failure and obstructive sleep apnea.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
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8
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Mashaqi S, Gozal D. Obstructive Sleep Apnea and Systemic Hypertension: Gut Dysbiosis as the Mediator? J Clin Sleep Med 2019; 15:1517-1527. [PMID: 31596218 PMCID: PMC6778338 DOI: 10.5664/jcsm.7990] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/20/2019] [Accepted: 04/23/2019] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Obstructive sleep apnea (OSA) and systemic hypertension (SH) are common and interrelated diseases. It is estimated that approximately 75% of treatment-resistant hypertension cases have an underlying OSA. Exploration of the gut microbiome is a new advance in medicine that has been linked to many comorbid illnesses, including SH and OSA. Here, we will review the literature in SH and gut dysbiosis, OSA and gut dysbiosis, and whether gut dysbiosis is common in both conditions. METHODS We reviewed the National Center for Biotechnology Information database, including PubMed and PubMed Central. We identified a total of 230 articles. The literature search was conducted using the phrase "obstructive sleep apnea and gut dysbiosis." Only original research articles were included. This yielded a total of 12 articles. RESULTS Most of the research conducted in this field was on animal models, and almost all trials confirmed that intermittent hypoxia models resulted in gut dysbiosis. Gut dysbiosis, however, can cause a state of low-grade inflammation through damage to the gut wall barrier resulting in "leaky gut." Neuroinflammation is a hallmark of the pathophysiology of OSA-induced SH. CONCLUSIONS Gut dysbiosis seems to be an important factor in the pathophysiology of OSA-induced hypertension. Reversing gut dysbiosis at an early stage through prebiotics and probiotics and fecal microbiota transplantation combined with positive airway pressure therapy may open new horizons of treatment to prevent SH. More studies are needed in humans to elicit the effect of positive airway pressure therapy on gut dysbiosis.
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Affiliation(s)
- Saif Mashaqi
- Division of Sleep Medicine, University of North Dakota School of Medicine – Sanford Health, Fargo, North Dakota
| | - David Gozal
- Department of Child Health and the Child Health Research Institute, University of Missouri School of Medicine, Columbia, Missouri
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9
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Zubcevic J, Richards EM, Yang T, Kim S, Sumners C, Pepine CJ, Raizada MK. Impaired Autonomic Nervous System-Microbiome Circuit in Hypertension. Circ Res 2019; 125:104-116. [PMID: 31219753 PMCID: PMC6588177 DOI: 10.1161/circresaha.119.313965] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypertension affects an estimated 103 million Americans, yet gaps in knowledge continue to limit its successful management. Rapidly emerging evidence is linking gut dysbiosis to many disorders and diseases including hypertension. The evolution of the -omics techniques has allowed determination of the abundance and potential function of gut bacterial species by next-generation bacterial sequencing, whereas metabolomics techniques report shifts in bacterial metabolites in the systemic circulation of hypertensive patients and rodent models of hypertension. The gut microbiome and host have evolved to exist in balance and cooperation, and there is extensive crosstalk between the 2 to maintain this balance, including during regulation of blood pressure. However, an understanding of the mechanisms of dysfunctional host-microbiome interactions in hypertension is still lacking. Here, we synthesize some of our recent data with published reports and present concepts and a rationale for our emerging hypothesis of a dysfunctional gut-brain axis in hypertension. Hopefully, this new information will improve the understanding of hypertension and help to address some of these knowledge gaps.
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Affiliation(s)
- Jasenka Zubcevic
- Department of Physiological Sciences, College of Veterinary Medicine; University of Florida, Gainesville FL32610
| | - Elaine M. Richards
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville FL32610
| | - Tao Yang
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville FL32610
| | - Seungbum Kim
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville FL32610
| | - Colin Sumners
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville FL32610
| | - Carl J Pepine
- Division of Cardiovascular Medicine, Department of Medicine, College of Medicine, University of Florida, Gainesville FL32610
| | - Mohan K Raizada
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville FL32610
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10
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Castro-Grattoni AL, Suarez-Giron M, Benitez I, Torres M, Almendros I, Farre R, Montserrat JM, Dalmases M, Gozal D, Sánchez-de-la-Torre M. Effect of age on the cardiovascular remodelling induced by chronic intermittent hypoxia as a murine model of sleep apnoea. Respirology 2019; 25:312-320. [PMID: 31215129 DOI: 10.1111/resp.13610] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 03/08/2019] [Accepted: 05/01/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVE Chronic intermittent hypoxia (CIH) is a major determinant of the cardiovascular morbidity associated with obstructive sleep apnoea (OSA), and the magnitude of CIH impact may be influenced by ageing. Here, we assessed the role of ageing in the early cardiovascular structural remodelling induced by severe CIH in a murine model of OSA. METHODS Cardiovascular remodelling was assessed in young (2 months old, n = 20) and aged (18 months old, n = 20) C57BL/6 female mice exposed to CIH (20% O2 for 40 s, 5% O2 for 20 s) or normoxia (room air) for 8 weeks (6 h/day). RESULTS Early vascular remodelling was observed in young mice exposed to CIH as illustrated by intima-media thickening (mean change: 4.6 ± 2.6 μm; P = 0.02), elastin fibre disorganization (mean change: 9.2 ± 4.5%; P = 0.02) and fragmentation (mean change: 2.5 ± 0.8%; P = 0.03), and collagen (mean change: 3.2 ± 0.6%; P = 0.001) and mucopolysaccharide accumulation (mean change: 2.4 ± 0.8%; P = 0.01). In contrast, vascular remodelling was not apparent in aged mice exposed to CIH. Furthermore, left ventricular perivascular fibrosis (mean change: 0.71 ± 0.1; P < 0.001) and hypertrophy (mean change: 0.17 ± 0.1; P = 0.038) were increased by CIH exposure in young mice, but not in aged mice. Principal component analysis identified similar cardiovascular alterations among the young mice exposed to CIH and both older mouse groups, suggesting that CIH induces premature cardiovascular senescence. CONCLUSION Cardiovascular remodelling induced by severe CIH is affected by the age at which CIH onset occurs, suggesting that the deleterious cardiovascular effects associated with CIH may be more pronounced in younger populations, and such changes resemble chronological age-related declines in cardiovascular structural integrity.
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Affiliation(s)
- Anabel L Castro-Grattoni
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, Lleida, Spain.,IRB Lleida, University of Lleida, Lleida, Spain
| | | | - Ivan Benitez
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, Lleida, Spain.,IRB Lleida, University of Lleida, Lleida, Spain
| | - Marta Torres
- Laboratori del son, Servei de Pneumologia, Hospital Clínic, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Isaac Almendros
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Ramon Farre
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Josep M Montserrat
- Laboratori del son, Servei de Pneumologia, Hospital Clínic, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Mireia Dalmases
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, Lleida, Spain.,IRB Lleida, University of Lleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - David Gozal
- Department of Child Health, University of Missouri, School of Medicine, Columbia, MO, USA
| | - Manuel Sánchez-de-la-Torre
- Group of Translational Research in Respiratory Medicine, Respiratory Department, Hospital University Arnau de Vilanova and Santa Maria, Lleida, Spain.,IRB Lleida, University of Lleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
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11
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Chen J, Gu H, Wurster RD, Cheng Z. Baroreflex Control of Heart Rate in Mice Overexpressing Human SOD1: Functional Changes in Central and Vagal Efferent Components. Neurosci Bull 2018; 35:91-97. [PMID: 30460537 PMCID: PMC6357281 DOI: 10.1007/s12264-018-0302-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/06/2018] [Indexed: 12/16/2022] Open
Abstract
Excessive reactive oxygen species (ROS) (such as the superoxide radical) are commonly associated with cardiac autonomic dysfunctions. Though superoxide dismutase 1 (SOD1) overexpression may protect against ROS damage to the autonomic nervous system, superoxide radical reduction may change normal physiological functions. Previously, we demonstrated that human SOD1 (hSOD1) overexpression does not change baroreflex bradycardia and tachycardia but rather increases aortic depressor nerve activity in response to arterial pressure changes in C57B6SJL-Tg (SOD1)2 Gur/J mice. Since the baroreflex arc includes afferent, central, and efferent components, the objective of this study was to determine whether hSOD1 overexpression alters the central and vagal efferent mediation of heart rate (HR) responses. Our data indicate that SOD1 overexpression decreased the HR responses to vagal efferent nerve stimulation but did not change the HR responses to aortic depressor nerve (ADN) stimulation. Along with the previous study, we suggest that SOD1 overexpression preserves normal baroreflex function but may differentially alter the functions of the ADN, vagal efferents, and central components. While SOD1 overexpression likely enhanced ADN function and the central mediation of bradycardia, it decreased vagal efferent control of HR.
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Affiliation(s)
- Jin Chen
- Division of Neuroscience and Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32816, USA
| | - He Gu
- Division of Neuroscience and Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32816, USA
| | - Robert D Wurster
- Department of Cellular and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood, IL, 60153, USA
| | - Zixi Cheng
- Division of Neuroscience and Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32816, USA.
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12
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Lucking EF, O'Connor KM, Strain CR, Fouhy F, Bastiaanssen TFS, Burns DP, Golubeva AV, Stanton C, Clarke G, Cryan JF, O'Halloran KD. Chronic intermittent hypoxia disrupts cardiorespiratory homeostasis and gut microbiota composition in adult male guinea-pigs. EBioMedicine 2018; 38:191-205. [PMID: 30446434 PMCID: PMC6306383 DOI: 10.1016/j.ebiom.2018.11.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/26/2018] [Accepted: 11/05/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Carotid body (peripheral oxygen sensor) sensitisation is pivotal in the development of chronic intermittent hypoxia (CIH)-induced hypertension. We sought to determine if exposure to CIH, modelling human sleep apnoea, adversely affects cardiorespiratory control in guinea-pigs, a species with hypoxia-insensitive carotid bodies. We reasoned that CIH-induced disruption of gut microbiota would evoke cardiorespiratory morbidity. METHODS Adult male guinea-pigs were exposed to CIH (6.5% O2 at nadir, 6 cycles.hour-1) for 8 h.day-1 for 12 consecutive days. FINDINGS CIH-exposed animals established reduced faecal microbiota species richness, with increased relative abundance of Bacteroidetes and reduced relative abundance of Firmicutes bacteria. Urinary corticosterone and noradrenaline levels were unchanged in CIH-exposed animals, but brainstem noradrenaline concentrations were lower compared with sham. Baseline ventilation was equivalent in CIH-exposed and sham animals; however, respiratory timing variability, sigh frequency and ventilation during hypoxic breathing were all lower in CIH-exposed animals. Baseline arterial blood pressure was unaffected by exposure to CIH, but β-adrenoceptor-dependent tachycardia and blunted bradycardia during phenylephrine-induced pressor responses was evident compared with sham controls. INTERPRETATION Increased carotid body chemo-afferent signalling appears obligatory for the development of CIH-induced hypertension and elevated chemoreflex control of breathing commonly reported in mammals, with hypoxia-sensitive carotid bodies. However, we reveal that exposure to modest CIH alters gut microbiota richness and composition, brainstem neurochemistry, and autonomic control of heart rate, independent of carotid body sensitisation, suggesting modulation of breathing and autonomic homeostasis via the microbiota-gut-brainstem axis. The findings have relevance to human sleep-disordered breathing. FUNDING The Department of Physiology, and APC Microbiome Ireland, UCC.
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Affiliation(s)
- Eric F Lucking
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Karen M O'Connor
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Conall R Strain
- Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Fiona Fouhy
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Thomaz F S Bastiaanssen
- Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - David P Burns
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Anna V Golubeva
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Catherine Stanton
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Gerard Clarke
- Department of Psychiatry and Neurobehavioural Science, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy & Neuroscience, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland.
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13
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Perim RR, Amorim MR, Bonagamba TLLGH, Machado BH. Previous exposure to chronic intermittent hypoxia blunts the development of one-kidney, one-clip hypertension in rats. Exp Physiol 2018; 103:473-482. [DOI: 10.1113/ep086734] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 01/10/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Raphael R. Perim
- Department of Physiology, School of Medicine of Ribeirão Preto; University of São Paulo; Ribeirão Preto SP 14049-900 Brazil
| | - Mateus R. Amorim
- Department of Physiology, School of Medicine of Ribeirão Preto; University of São Paulo; Ribeirão Preto SP 14049-900 Brazil
| | - The Late Leni G. H. Bonagamba
- Department of Physiology, School of Medicine of Ribeirão Preto; University of São Paulo; Ribeirão Preto SP 14049-900 Brazil
| | - Benedito H. Machado
- Department of Physiology, School of Medicine of Ribeirão Preto; University of São Paulo; Ribeirão Preto SP 14049-900 Brazil
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14
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Cheng Z(J. Vagal cardiac efferent innervation in F344 rats: Effects of chronic intermittent hypoxia. Auton Neurosci 2017; 203:9-16. [DOI: 10.1016/j.autneu.2016.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 10/05/2016] [Accepted: 10/27/2016] [Indexed: 12/27/2022]
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15
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Morgan BJ, Bates ML, Rio RD, Wang Z, Dopp JM. Oxidative stress augments chemoreflex sensitivity in rats exposed to chronic intermittent hypoxia. Respir Physiol Neurobiol 2016; 234:47-59. [PMID: 27595979 DOI: 10.1016/j.resp.2016.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/29/2016] [Accepted: 09/01/2016] [Indexed: 12/31/2022]
Abstract
Chronic exposure to intermittent hypoxia (CIH) elicits plasticity of the carotid sinus and phrenic nerves via reactive oxygen species (ROS). To determine whether CIH-induced alterations in ventilation, metabolism, and heart rate are also dependent on ROS, we measured responses to acute hypoxia in conscious rats after 14 and 21 d of either CIH or normoxia (NORM), with or without concomitant administration of allopurinol (xanthine oxidase inhibitor), combined allopurinol plus losartan (angiotensin II type 1 receptor antagonist), or apocynin (NADPH oxidase inhibitor). Carotid body nitrotyrosine production was measured by immunohistochemistry. CIH produced an increase in the ventilatory response to acute hypoxia that was virtually eliminated by all three pharmacologic interventions. CIH caused a robust increase in carotid body nitrotyrosine production that was greatly attenuated by allopurinol plus losartan and by apocynin but unaffected by allopurinol. CIH caused a decrease in metabolic rate and a reduction in hypoxic bradycardia. Both of these effects were prevented by allopurinol, allopurinol plus losartan, and apocynin.
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Affiliation(s)
- Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health: University of Wisconsin, Madison, WI 53706, USA; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health; University of Wisconsin, Madison, WI 53706, USA.
| | - Melissa L Bates
- Department of Health and Human Physiology, College of Liberal Arts and Sciences; University of Iowa, Iowa City, IA 52242, USA
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile
| | - Zunyi Wang
- Department of Surgical Sciences, School of Veterinary Medicine; University of Wisconsin, Madison, WI 53706, USA
| | - John M Dopp
- Pharmacy Practice Division, School of Pharmacy; University of Wisconsin, Madison, WI 53705, USA
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16
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Dyavanapalli J, Dergacheva O, Wang X, Mendelowitz D. Parasympathetic Vagal Control of Cardiac Function. Curr Hypertens Rep 2016; 18:22. [PMID: 26849575 DOI: 10.1007/s11906-016-0630-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This brief review focuses on four new topics, with novel and clinically significant consequences, concerning the powerful influence of parasympathetic activity on cardiac function. In this short summary, we will highlight very recent and important work, published in the last 3-4 years, that (1) challenges the paradigm that parasympathetic activity to the heart is involved in the control of heart rate but plays little role in other cardiac functions, (2) characterizes important long-range synaptic pathways to parasympathetic cardiac vagal neurons that are involved in "higher" brain functions (such as arousal and emotional challenges), (3) asks whether implantable chronic vagal nerve stimulation is a promising clinical tool for treating cardiovascular diseases, and (4) describes newly identified neuropeptides and other modulators that can influence the generation and maintenance of parasympathetic activity to the heart.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA.
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17
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Abstract
Sleep apnea (SA) is increasing in prevalence and is commonly comorbid with hypertension. Chronic intermittent hypoxia is used to model the arterial hypoxemia seen in SA, and through this paradigm, the mechanisms that underlie SA-induced hypertension are becoming clear. Cyclic hypoxic exposure during sleep chronically stimulates the carotid chemoreflexes, inducing sensory long-term facilitation, and drives sympathetic outflow from the hindbrain. The elevated sympathetic tone drives hypertension and renal sympathetic activity to the kidneys resulting in increased plasma renin activity and eventually angiotensin II (Ang II) peripherally. Upon waking, when respiration is normalized, the sympathetic activity does not diminish. This is partially because of adaptations leading to overactivation of the hindbrain regions controlling sympathetic outflow such as the nucleus tractus solitarius (NTS), and rostral ventrolateral medulla (RVLM). The sustained sympathetic activity is also due to enhanced synaptic signaling from the forebrain through the paraventricular nucleus (PVN). During the waking hours, when the chemoreceptors are not exposed to hypoxia, the forebrain circumventricular organs (CVOs) are stimulated by peripherally circulating Ang II from the elevated plasma renin activity. The CVOs and median preoptic nucleus chronically activate the PVN due to the Ang II signaling. All together, this leads to elevated nocturnal mean arterial pressure (MAP) as a response to hypoxemia, as well as inappropriately elevated diurnal MAP in response to maladaptations.
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Affiliation(s)
- Brent Shell
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Katelynn Faulk
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - J Thomas Cunningham
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, EAD 332B, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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18
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Morgan BJ, Adrian R, Wang ZY, Bates ML, Dopp JM. Chronic intermittent hypoxia alters ventilatory and metabolic responses to acute hypoxia in rats. J Appl Physiol (1985) 2016; 120:1186-95. [PMID: 26917692 DOI: 10.1152/japplphysiol.00015.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/22/2016] [Indexed: 12/18/2022] Open
Abstract
We determined the effects of chronic exposure to intermittent hypoxia (CIH) on chemoreflex control of ventilation in conscious animals. Adult male Sprague-Dawley rats were exposed to CIH [nadir oxygen saturation (SpO2), 75%; 15 events/h; 10 h/day] or normoxia (NORM) for 21 days. We assessed the following responses to acute, graded hypoxia before and after exposures: ventilation (V̇e, via barometric plethysmography), V̇o2 and V̇co2 (analysis of expired air), heart rate (HR), and SpO2 (pulse oximetry via neck collar). We quantified hypoxia-induced chemoreceptor sensitivity by calculating the stimulus-response relationship between SpO2 and the ventilatory equivalent for V̇co2 (linear regression). An additional aim was to determine whether CIH causes proliferation of carotid body glomus cells (using bromodeoxyuridine). CIH exposure increased the slope of the V̇e/V̇co2/SpO2 relationship and caused hyperventilation in normoxia. Bromodeoxyuridine staining was comparable in CIH and NORM. Thus our CIH paradigm augmented hypoxic chemosensitivity without causing glomus cell proliferation.
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Affiliation(s)
- Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin;
| | - Russell Adrian
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Zun-Yi Wang
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin
| | - Melissa L Bates
- Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa; and
| | - John M Dopp
- Pharmacy Practice Division, School of Pharmacy, University of Wisconsin, Madison, Wisconsin
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19
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SOD1 Overexpression Preserves Baroreflex Control of Heart Rate with an Increase of Aortic Depressor Nerve Function. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:3686829. [PMID: 26823951 PMCID: PMC4707341 DOI: 10.1155/2016/3686829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/01/2015] [Indexed: 02/07/2023]
Abstract
Overproduction of reactive oxygen species (ROS), such as the superoxide radical (O2∙−), is associated with diseases which compromise cardiac autonomic function. Overexpression of SOD1 may offer protection against ROS damage to the cardiac autonomic nervous system, but reductions of O2∙− may interfere with normal cellular functions. We have selected the C57B6SJL-Tg (SOD1)2 Gur/J mouse as a model to determine whether SOD1 overexpression alters cardiac autonomic function, as measured by baroreflex sensitivity (BRS) and aortic depressor nerve (ADN) recordings, as well as evaluation of baseline heart rate (HR) and mean arterial pressure (MAP). Under isoflurane anesthesia, C57 wild-type and SOD1 mice were catheterized with an arterial pressure transducer and measurements of HR and MAP were taken. After establishing a baseline, hypotension and hypertension were induced by injection of sodium nitroprusside (SNP) and phenylephrine (PE), respectively, and ΔHR versus ΔMAP were recorded as a measure of baroreflex sensitivity (BRS). SNP and PE treatment were administered sequentially after a recovery period to measure arterial baroreceptor activation by recording aortic depressor nerve activity. Our findings show that overexpression of SOD1 in C57B6SJL-Tg (SOD1)2 Gur/J mouse preserved the normal HR, MAP, and BRS but enhanced aortic depressor nerve function.
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20
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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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21
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Del Rio R, Moya EA, Iturriaga R. Carotid body potentiation during chronic intermittent hypoxia: implication for hypertension. Front Physiol 2014; 5:434. [PMID: 25429271 PMCID: PMC4228839 DOI: 10.3389/fphys.2014.00434] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/24/2014] [Indexed: 11/30/2022] Open
Abstract
Autonomic dysfunction is involved in the development of hypertension in humans with obstructive sleep apnea, and animals exposed to chronic intermittent hypoxia (CIH). It has been proposed that a crucial step in the development of the hypertension is the potentiation of the carotid body (CB) chemosensory responses to hypoxia, but the temporal progression of the CB chemosensory, autonomic and hypertensive changes induced by CIH are not known. We tested the hypothesis that CB potentiation precedes the autonomic imbalance and the hypertension in rats exposed to CIH. Thus, we studied the changes in CB chemosensory and ventilatory responsiveness to hypoxia, the spontaneous baroreflex sensitivity (BRS), heart rate variability (HRV) and arterial blood pressure in pentobarbital anesthetized rats exposed to CIH for 7, 14, and 21 days. After 7 days of CIH, CB chemosensory and ventilatory responses to hypoxia were enhanced, while BRS was significantly reduced by 2-fold in CIH-rats compared to sham-rats. These alterations persisted until 21 days of CIH. After 14 days, CIH shifted the HRV power spectra suggesting a predominance of sympathetic over parasympathetic tone. In contrast, hypertension was found after 21 days of CIH. Concomitant changes between the gain of spectral HRV, BRS, and ventilatory hypoxic chemoreflex showed that the CIH-induced BRS attenuation preceded the HRV changes. CIH induced a simultaneous decrease of the BRS gain along with an increase of the hypoxic ventilatory gain. Present results show that CIH-induced persistent hypertension was preceded by early changes in CB chemosensory control of cardiorespiratory and autonomic function.
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Affiliation(s)
- Rodrigo Del Rio
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile ; Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
| | - Esteban A Moya
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
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22
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Dergacheva O. Chronic intermittent hypoxia alters neurotransmission from lateral paragigantocellular nucleus to parasympathetic cardiac neurons in the brain stem. J Neurophysiol 2014; 113:380-9. [PMID: 25318765 DOI: 10.1152/jn.00302.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Patients with sleep-related disorders, including obstructive sleep apnea (OSA), have an increased risk of cardiovascular diseases. OSA events are more severe in rapid eye movement (REM) sleep. REM sleep further increases the risk of adverse cardiovascular events by diminishing cardioprotective parasympathetic activity. The mechanisms underlying REM sleep-related reduction in parasympathetic activity likely include activation of inhibitory input to cardiac vagal neurons (CVNs) in the brain stem originating from the lateral paragigantocellular nucleus (LPGi), a nucleus that plays a role in REM sleep control. This study tests the hypothesis that chronic intermittent hypoxia and hypercapnia (CIHH), an animal model of OSA, inhibits CVNs because of exaggeration of the GABAergic pathway from the LPGi to CVNs. GABAergic neurotransmission to CVNs evoked by electrical stimulation of the LPGi was examined with whole cell patch-clamp recordings in an in vitro brain slice preparation in rats exposed to CIHH and control rats. GABAergic synaptic events were enhanced after 4-wk CIHH in both male and female rats, to a greater degree in males. Acute hypoxia and hypercapnia (H/H) reversibly diminished the LPGi-evoked GABAergic neurotransmission to CVNs. However, GABAergic synaptic events were enhanced after acute H/H in CIHH male animals. Orexin-A elicited a reversible inhibition of LPGi-evoked GABAergic currents in control animals but evoked no significant changes in CIHH male rats. In conclusion, exaggerated inhibitory neurotransmission from the LPGi to CVNs in CIHH animals would reduce cardioprotective parasympathetic activity and enhance the risk of adverse cardiovascular events.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, District of Columbia
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23
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Vestibular evoked myogenic potential responses in obstructive sleep apnea syndrome. Eur Arch Otorhinolaryngol 2014; 272:3137-41. [DOI: 10.1007/s00405-014-3294-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 09/17/2014] [Indexed: 02/06/2023]
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Dergacheva O, Dyavanapalli J, Piñol RA, Mendelowitz D. Chronic intermittent hypoxia and hypercapnia inhibit the hypothalamic paraventricular nucleus neurotransmission to parasympathetic cardiac neurons in the brain stem. Hypertension 2014; 64:597-603. [PMID: 24958501 DOI: 10.1161/hypertensionaha.114.03603] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Obstructive sleep apnea is associated with chronic intermittent hypoxia/hypercapnia (CIHH) episodes during sleep that heighten sympathetic and diminish parasympathetic activity to the heart. Although one population of neurons in the paraventricular nucleus of the hypothalamus strongly influences sympathetic tone and has increased activity after CIHH, little is known about the role of this pathway to parasympathetic neurons and how this network is altered in CIHH. We hypothesized that CIHH inhibits the excitatory pathway from the paraventricular nucleus of the hypothalamus to parasympathetic cardiac vagal neurons in the brain stem. To test this hypothesis, channelrhodopsin was selectively expressed, using viral vectors, in neurons in the paraventricular nucleus of the hypothalamus and channelrhodopsin-expressing fibers were photoactivated to evoke postsynaptic currents in cardiac vagal neurons in brain stem slices. Excitatory postsynaptic currents were diminished in animals exposed to CIHH. The paired-pulse and prolonged facilitation of the postsynaptic current amplitudes and frequencies evoked by paired and bursts of photoactivation of channelrhodopsin fibers, respectively, occurred in unexposed rats but were blunted in CIHH animals. In response to an acute challenge of hypoxia/hypercapnia, the amplitude of postsynaptic events was unchanged during, but increased after hypoxia/hypercapnia in unexposed animals. In contrast, postsynaptic currents were inhibited during hypoxia/hypercapnia in rats exposed to CIHH. In conclusion, the excitatory pathway to cardiac vagal neurons is diminished in response to both acute and chronic exposures to hypoxia/hypercapnia. This could elicit a reduced cardioprotective parasympathetic activity and an enhanced risk of adverse cardiovascular events in episodes of apnea and chronic obstructive sleep apnea.
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Affiliation(s)
- Olga Dergacheva
- From the Department of Pharmacology and Physiology, Department of Anesthesiology and Critical Care Medicine, The George Washington University, Washington, DC
| | - Jhansi Dyavanapalli
- From the Department of Pharmacology and Physiology, Department of Anesthesiology and Critical Care Medicine, The George Washington University, Washington, DC
| | - Ramón A Piñol
- From the Department of Pharmacology and Physiology, Department of Anesthesiology and Critical Care Medicine, The George Washington University, Washington, DC
| | - David Mendelowitz
- From the Department of Pharmacology and Physiology, Department of Anesthesiology and Critical Care Medicine, The George Washington University, Washington, DC.
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Dyavanapalli J, Jameson H, Dergacheva O, Jain V, Alhusayyen M, Mendelowitz D. Chronic intermittent hypoxia-hypercapnia blunts heart rate responses and alters neurotransmission to cardiac vagal neurons. J Physiol 2014; 592:2799-811. [PMID: 24835174 DOI: 10.1113/jphysiol.2014.273482] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Patients with obstructive sleep apnoea experience chronic intermittent hypoxia-hypercapnia (CIHH) during sleep that elicit sympathetic overactivity and diminished parasympathetic activity to the heart, leading to hypertension and depressed baroreflex sensitivity. The parasympathetic control of heart rate arises from pre-motor cardiac vagal neurons (CVNs) located in nucleus ambiguus (NA) and dorsal motor nucleus of the vagus (DMNX). The mechanisms underlying diminished vagal control of heart rate were investigated by studying the changes in blood pressure, heart rate, and neurotransmission to CVNs evoked by acute hypoxia-hypercapnia (H-H) and CIHH. In vivo telemetry recordings of blood pressure and heart rate were obtained in adult rats during 4 weeks of CIHH exposure. Retrogradely labelled CVNs were identified in an in vitro brainstem slice preparation obtained from adult rats exposed either to air or CIHH for 4 weeks. Postsynaptic inhibitory or excitatory currents were recorded using whole cell voltage clamp techniques. Rats exposed to CIHH had increases in blood pressure, leading to hypertension, and blunted heart rate responses to acute H-H. CIHH induced an increase in GABAergic and glycinergic neurotransmission to CVNs in NA and DMNX, respectively; and a reduction in glutamatergic neurotransmission to CVNs in both nuclei. CIHH blunted the bradycardia evoked by acute H-H and abolished the acute H-H evoked inhibition of GABAergic transmission while enhancing glycinergic neurotransmission to CVNs in NA. These changes with CIHH inhibit CVNs and vagal outflow to the heart, both in acute and chronic exposures to H-H, resulting in diminished levels of cardioprotective parasympathetic activity to the heart as seen in OSA patients.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA
| | - Heather Jameson
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA
| | - Vivek Jain
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA Department of Medicine, Medical Faculty Associates, The George Washington University, Washington, DC, 20037, USA
| | - Mona Alhusayyen
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, 2300 Eye Street NW, The George Washington University, Washington, DC, 20037, USA
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26
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Dergacheva O, Weigand LA, Dyavanapalli J, Mares J, Wang X, Mendelowitz D. Function and modulation of premotor brainstem parasympathetic cardiac neurons that control heart rate by hypoxia-, sleep-, and sleep-related diseases including obstructive sleep apnea. PROGRESS IN BRAIN RESEARCH 2014; 212:39-58. [PMID: 25194192 DOI: 10.1016/b978-0-444-63488-7.00003-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Parasympathetic cardiac vagal neurons (CVNs) in the brainstem dominate the control of heart rate. Previous work has determined that these neurons are inherently silent, and their activity is largely determined by synaptic inputs to CVNs that include four major types of synapses that release glutamate, GABA, glycine, or serotonin. Whereas prior reviews have focused on glutamatergic, GABAergic and glycinergic pathways, and the receptors in CVNs activated by these neurotransmitters, this review focuses on the alterations in CVN activity with hypoxia-, sleep-, and sleep-related cardiovascular diseases including obstructive sleep apnea.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA
| | - Letitia A Weigand
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA
| | - Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA
| | - Jacquelyn Mares
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA
| | - Xin Wang
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, School of Medicine, George Washington University, Washington, DC, USA.
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Lin M, Hatcher JT, Wurster RD, Chen QH, Cheng ZJ. Characteristics of single large-conductance Ca2+-activated K+ channels and their regulation of action potentials and excitability in parasympathetic cardiac motoneurons in the nucleus ambiguus. Am J Physiol Cell Physiol 2013; 306:C152-66. [PMID: 24196530 DOI: 10.1152/ajpcell.00423.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large-conductance Ca2(+)-activated K+ channels (BK) regulate action potential (AP) properties and excitability in many central neurons. However, the properties and functional roles of BK channels in parasympathetic cardiac motoneurons (PCMNs) in the nucleus ambiguus (NA) have not yet been well characterized. In this study, the tracer X-rhodamine-5 (and 6)-isothiocyanate (XRITC) was injected into the pericardial sac to retrogradely label PCMNs in FVB mice at postnatal 7-9 days. Two days later, XRITC-labeled PCMNs in brain stem slices were identified. Using excised patch single-channel recordings, we identified voltage-gated and Ca(2+)-dependent BK channels in PCMNs. The majority of BK channels exhibited persistent channel opening during voltage holding. These BK channels had a conductance of 237 pS and a 50% opening probability at +27.9 mV, the channel open time constant was 3.37 ms at +20 mV, and dwell time increased exponentially as the membrane potential depolarized. At the +20-mV holding potential, the [Ca2+]50 was 15.2 μM with a P0.5 of 0.4. Occasionally, some BK channels showed a transient channel opening and fast inactivation. Using whole cell voltage clamp, we found that BK channel mediated outward currents and afterhyperpolarization currents (IAHP). Using whole cell current clamp, we found that application of BK channel blocker iberiotoxin (IBTX) increased spike half-width and suppressed fast afterhyperpolarization (fAHP) amplitude following single APs. In addition, IBTX application increased spike half-width and reduced the spike frequency-dependent AP broadening in trains and spike frequency adaption (SFA). Furthermore, BK channel blockade decreased spike frequency. Collectively, these results demonstrate that PCMNs have BK channels that significantly regulate AP repolarization, fAHP, SFA, and spike frequency. We conclude that activation of BK channels underlies one of the mechanisms for facilitation of PCMN excitability.
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Affiliation(s)
- Min Lin
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida
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28
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Yamamoto K, Eubank W, Franzke M, Mifflin S. Resetting of the sympathetic baroreflex is associated with the onset of hypertension during chronic intermittent hypoxia. Auton Neurosci 2012; 173:22-7. [PMID: 23167993 DOI: 10.1016/j.autneu.2012.10.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 11/26/2022]
Abstract
Chronic intermittent hypoxia (CIH) is a model of arterial hypoxemia that accompanies sleep apnea and increases resting arterial pressure (AP). We examined the effects of 7 days of exposure to CIH on arterial baroreflex control of renal sympathetic nerve activity (RSNA) and heart rate (HR) in rats. Sprague-Dawley rats (15±2 weeks old) were exposed to CIH (9% oxygen for 3 min every 10 min, 8 h per day) for 7 days (n=16) while control rats (n=18) were maintained in normoxia. Baroreflex regulation of RSNA and HR were estimated in Inactin anesthetized and artificially ventilated rats during infusions of phenylephrine and nitroprusside to manipulate AP. After exposure to CIH, resting mean AP was higher in CIH than that in control group (115±7 vs. 105±7, P<0.001). Resting HR did not differ between the two groups. Exposure to CIH shifted the AP-RSNA relationship rightward (approximately 10 mm Hg, P<0.01). CIH did not alter maximum gain of the baroreflex control of RSNA (-2.6±0.6 vs. -2.5±0.6 arbitrary units (a.u.)/mm Hg) and HR (-1.8±0.6 vs. -1.8±0.7 bpm/mm Hg, CIH vs. control). In addition, cardiac spontaneous baroreflex sensitivity in conscious rats (n=8) also did not change during exposure to CIH. These results indicate that resetting of the sympathetic baroreflex control, rather than an impairment of its sensitivity, is associated with an onset of hypertension induced by CIH.
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Affiliation(s)
- Kenta Yamamoto
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Centre, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
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30
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Gozal D, Hakim F, Kheirandish-Gozal L. Chemoreceptors, baroreceptors, and autonomic deregulation in children with obstructive sleep apnea. Respir Physiol Neurobiol 2012; 185:177-85. [PMID: 22954503 DOI: 10.1016/j.resp.2012.08.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 11/17/2022]
Abstract
Obstructive sleep apnea (OSA) is highly prevalent sleep disorder of breathing in both adults and children that is fraught with substantial cardiovascular morbidities, the latter being attributable to a complex interplay between intermittent hypoxia (IH), episodic hypercapnia, recurrent large intra-thoracic pressure swings, and sleep disruption. Alterations in autonomic nervous system function could underlie the perturbations in cardiovascular, neurocognitive, immune, endocrine and metabolic functions that affect many of the patients suffering from OSA. Although these issues have received substantial attention in adults, the same has thus far failed to occur in children, creating a quasi misperception that children are protected. Here, we provide a critical overview of the evidence supporting the presence of autonomic nervous system (ANS) perturbations in children with OSA, draw some parallel assessments to known mechanisms in rodents and adult humans, particularly, peripheral and central chemoreceptor and baroreceptor pathways, and suggest future research directions.
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Affiliation(s)
- David Gozal
- Department of Pediatrics, Comer Children's Hospital, The University of Chicago, Chicago, IL, USA.
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31
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Hakim F, Gozal D, Kheirandish-Gozal L. Sympathetic and catecholaminergic alterations in sleep apnea with particular emphasis on children. Front Neurol 2012; 3:7. [PMID: 22319509 PMCID: PMC3268184 DOI: 10.3389/fneur.2012.00007] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 01/10/2012] [Indexed: 01/04/2023] Open
Abstract
Sleep is involved in the regulation of major organ functions in the human body, and disruption of sleep potentially can elicit organ dysfunction. Obstructive sleep apnea (OSA) is the most prevalent sleep disorder of breathing in adults and children, and its manifestations reflect the interactions between intermittent hypoxia, intermittent hypercapnia, increased intra-thoracic pressure swings, and sleep fragmentation, as elicited by the episodic changes in upper airway resistance during sleep. The sympathetic nervous system is an important modulator of the cardiovascular, immune, endocrine and metabolic systems, and alterations in autonomic activity may lead to metabolic imbalance and organ dysfunction. Here we review how OSA and its constitutive components can lead to perturbation of the autonomic nervous system in general, and to altered regulation of catecholamines, both of which then playing an important role in some of the mechanisms underlying OSA-induced morbidities.
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Affiliation(s)
- Fahed Hakim
- Department of Pediatrics, Comer Children's Hospital, The University of Chicago Chicago, IL, USA
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32
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Connes P. Altered Autonomic Nervous System Function in Sickle Cell Disease. Am J Respir Crit Care Med 2011; 184:398-400. [DOI: 10.1164/rccm.201105-0941ed] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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33
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Zoccal DB, Machado BH. Coupling Between Respiratory and Sympathetic Activities as a Novel Mechanism Underpinning Neurogenic Hypertension. Curr Hypertens Rep 2011; 13:229-36. [DOI: 10.1007/s11906-011-0198-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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34
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Dergacheva O, Griffioen KJ, Neff RA, Mendelowitz D. Respiratory modulation of premotor cardiac vagal neurons in the brainstem. Respir Physiol Neurobiol 2010; 174:102-10. [PMID: 20452467 PMCID: PMC2932818 DOI: 10.1016/j.resp.2010.05.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/30/2010] [Accepted: 05/03/2010] [Indexed: 02/09/2023]
Abstract
The respiratory and cardiovascular systems are highly intertwined, both anatomically and physiologically. Respiratory and cardiovascular neurons are often co-localized in the same brainstem regions, and this is particularly evident in the ventral medulla which contains presympathetic neurons in the rostral ventrolateral medulla, premotor parasympathetic cardioinhibitory neurons in the nucleus ambiguus, and the ventral respiratory group, which includes the pre-Botzinger complex. Anatomical studies of respiratory and cardiovascular neurons have demonstrated that many of these neurons have projections and axon collateral processes which extend into their neighboring cardiorespiratory regions providing an anatomical substrate for cardiorespiratory interactions. As other reports in this Special Issue of Respiratory Physiology & Neurobiology focus on interactions between the respiratory network and baroreceptors, neurons in the nucleus tractus solitarius, presympathetic neurons and sympathetic activity, this report will focus on the respiratory modulation of parasympathetic activity and the neurons that generate parasympathetic activity to the heart, cardiac vagal neurons.
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Affiliation(s)
- Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037, USA
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35
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Lin M, Hatcher JT, Chen QH, Wurster RD, Cheng ZJ. Small conductance Ca2+-activated K+ channels regulate firing properties and excitability in parasympathetic cardiac motoneurons in the nucleus ambiguus. Am J Physiol Cell Physiol 2010; 299:C1285-98. [PMID: 20739619 DOI: 10.1152/ajpcell.00134.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Small conductance Ca(2+)-activated K(+) channels (SK) regulate action potential (AP) firing properties and excitability in many central neurons. However, the functional roles of SK channels of parasympathetic cardiac motoneurons (PCMNs) in the nucleus ambiguus have not yet been well characterized. In this study, the tracer X-rhodamine-5 (and 6)-isothiocyanate (XRITC) was injected into the pericardial sac to retrogradely label PCMNs in FVB mice at postnatal days 7-9. Two days later, XRITC-labeled PCMNs in brain stem slices were identified. With the use of whole cell current clamp, single APs and spike trains of different frequencies were evoked by current injections. We found that 1) PCMNs have two different firing patterns: the majority of PCMNs (90%) exhibited spike frequency adaptation (SFA) and the rest (10%) showed less or no adaptation; 2) application of the specific SK channel blocker apamin significantly increased spike half-width in single APs and trains and reduced the spike frequency-dependent AP broadening in trains; 3) SK channel blockade suppressed afterhyperpolarization (AHP) amplitude following single APs and trains and abolished spike-frequency dependence of AHP in trains; and 4) SK channel blockade increased the spike frequency but did not alter the pattern of SFA. Using whole cell voltage clamp, we measured outward currents and afterhyperpolarization current (I(AHP)). SK channel blockade revealed that SK-mediated outward currents had both transient and persistent components. After bath application of apamin and Ca(2+)-free solution, we found that apamin-sensitive and Ca(2+)-sensitive I(AHP) were comparable, confirming that SK channels may contribute to a major portion of Ca(2+)-activated K(+) channel-mediated I(AHP). These results suggest that PCMNs have SK channels that significantly regulate AP repolarization, AHP, and spike frequency but do not affect SFA. We conclude that activation of SK channels underlies one of the mechanisms for negative control of PCMN excitability.
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Affiliation(s)
- Min Lin
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
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36
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Zhang JH, Fung SJ, Xi M, Sampogna S, Chase MH. Apnea produces neuronal degeneration in the pons and medulla of guinea pigs. Neurobiol Dis 2010; 40:251-64. [PMID: 20554036 DOI: 10.1016/j.nbd.2010.05.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 05/19/2010] [Accepted: 05/30/2010] [Indexed: 12/18/2022] Open
Abstract
Obstructive sleep apnea and other sleep-related breathing disorders result in recurrent periods of oxygen deprivation (hypoxia), hypercapnia and an increase in the cellular production of reactive oxygen species (oxidative stress-related injury). Individuals with these disorders suffer from a variety of cellular abnormalities that result in cardiopulmonary dysfunctions, disturbances in sleep and other pathologies. In the present experiment, using an animal model of sleep apnea, we determined that the degeneration of neurons and glia, due to apoptosis, occurs in specific regions of the pons and medulla. Adult guinea pigs, which were divided into control (normoxic) and experimental (hypoxic) groups, were anesthetized with alpha-chloralose and immobilized with Flaxedil. Apnea (hypoxia) was induced by ventilatory arrest in order to desaturate the oxyhemoglobin to 75% SpO(2). A sequence of apnea, followed by ventilation with recovery to >95% SpO(2), was repeated for a period of 3h. At the end of the period of recurrent apnea, the animals were perfused and brain sections were immunostained with a mouse monoclonal antibody raised against single-stranded DNA (ssDNA). Apoptotic neurons and glia, which were not found in the control group of animals, were present in brainstem regions in hypoxic group of animals; these regions involved in the control of respiration (e.g., the parafacial respiratory group and the ventral respiratory group), cardiovascular functions (e.g., the nucleus ambiguus, the nucleus tractus solitarius and the dorsal motor nucleus of the vagus) as well as REM sleep (the nucleus pontis oralis) and wakefulness (e.g., the dorsal raphe and locus ceruleus). We suggest apoptotic neurons and glia in critical areas of the pons and medulla results in many of the comorbidities experienced by patients with sleep-disordered breathing pathologies.
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Yan B, Li L, Harden SW, Epstein PN, Wurster RD, Cheng ZJ. Diabetes induces neural degeneration in nucleus ambiguus (NA) and attenuates heart rate control in OVE26 mice. Exp Neurol 2009; 220:34-43. [PMID: 19615367 DOI: 10.1016/j.expneurol.2009.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 06/30/2009] [Accepted: 07/06/2009] [Indexed: 12/22/2022]
Abstract
Baroreflex sensitivity is impaired by diabetes mellitus. Previously, we found that diabetes induces a deficit of central mediation of baroreflex-mediated bradycardia. In this study, we assessed whether diabetes induces degeneration of the nucleus ambiguus (NA) and reduces heart rate (HR) responses to l-Glutamate (L-Glu) microinjection into the NA. FVB control and OVE26 diabetic mice (5-6 months) were anesthetized. Different doses of L-Glu (0.1-5 mM/l, 20 nl) were delivered into the left NA using a multi-channel injector. In other animals, the left vagus was electrically stimulated at 1-40 Hz (1 ms, 0.5 mA, 20 s). HR and mean arterial blood pressure (MAP) responses to L-Glu microinjections into the NA and to the electrical stimulation of the vagus were measured. The NA region was defined by tracer TMR-D injection into the ipsilateral nodose ganglion to retrogradely label vagal motoneurons in the NA. Brainstem slices at -600, -300, 0, +300, and +600 mum relative to the obex were processed using Nissl staining and the number of NA motoneurons was counted. Compared with FVB control, we found in OVE26 mice that: 1) HR responses to L-Glu injection into the NA at doses of 0.2-0.4 (mM/l, 20 nl) were attenuated (p<0.05), but MAP responses were unchanged (p>0.05). 2) HR responses to vagal stimulation were increased (p<0.05). 3) The total number of NA (left and right) motoneurons was reduced (p<0.05). Taken together, we concluded that diabetes reduces NA control of HR and induces degeneration of NA motoneurons. Degeneration of NA cardiac motoneurons may contribute to impairment of reflex-bradycardia in OVE26 diabetic mice.
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Affiliation(s)
- Binbin Yan
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
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Zoccal DB, Bonagamba LGH, Paton JFR, Machado BH. Sympathetic-mediated hypertension of awake juvenile rats submitted to chronic intermittent hypoxia is not linked to baroreflex dysfunction. Exp Physiol 2009; 94:972-83. [PMID: 19578126 DOI: 10.1113/expphysiol.2009.048306] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the present study, we evaluated the mechanisms underpinning the hypertension observed in freely moving juvenile rats submitted to chronic intermittent hypoxia (CIH). Male juvenile Wistar rats (20-21 days old) were submitted to CIH (6% O(2) for 40 s every 9 min, 8 h day(1)) for 10 days while control rats were maintained in normoxia. Prior to CIH, baseline systolic arterial pressure (SAP), measured indirectly, was similar between groups (86 +/- 1 versus 87 +/- 1 mmHg). After exposure to CIH, SAP recorded directly was higher in the CIH (n = 28) than in the control group (n = 29; 131 +/- 3 versus 115 +/- 2 mmHg, P < 0.05). This higher SAP of CIH rats presented an augmented power of oscillatory components at low (10.05 +/- 0.91 versus 5.02 +/- 0.63 mmHg(2), P < 0.05) and high (respiratory-related) frequencies (12.42 +/- 2.46 versus 3.28 +/- 0.61 mmHg(2), P < 0.05) in comparison with control animals. In addition, rats exposed to CIH also exhibited an increased cardiac baroreflex gain (3.11 +/- 0.08 versus 2.1 +/- 0.10 beats min(1) mmHg(1), P < 0.0001), associated with a shift to the right of the operating point, in comparison with control rats. Administration of hexamethonium (ganglionic blocker, i.v.), injected after losartan (angiotensin II type 1 receptor antagonist) and [beta-mercapto-beta,beta-cyclopenta-methylenepropionyl(1), O-Me-Tyr(2), Arg(8)]-vasopressin (vasopressin type 1a receptor antagonist), produced a larger depressor response in the CIH (n = 8) than in the control group (n = 9; 49 +/- 2 versus 39 +/- 2 mmHg, P < 0.05). Fifteen days after the cessation of exposure to CIH, the mean arterial pressure of CIH rats returned to normal levels. The data indicate that the sympathetic-mediated hypertension observed in conscious juvenile rats exposed to CIH is not secondary to a reduction in cardiac baroreflex gain and exhibits a higher respiratory modulation, indicating that an enhanced respiratory-sympathetic coupling seems to be the major factor contributing to hypertension in rats exposed to CIH.
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Affiliation(s)
- Daniel B Zoccal
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
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Yan B, Li L, Harden SW, Gozal D, Lin Y, Wead WB, Wurster RD, Cheng ZJ. Chronic intermittent hypoxia impairs heart rate responses to AMPA and NMDA and induces loss of glutamate receptor neurons in nucleus ambiguous of F344 rats. Am J Physiol Regul Integr Comp Physiol 2008; 296:R299-308. [PMID: 19020286 DOI: 10.1152/ajpregu.90412.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic intermittent hypoxia (CIH), as occurs in sleep apnea, impairs baroreflex-mediated reductions in heart rate (HR) and enhances HR responses to electrical stimulation of vagal efferent. We tested the hypotheses that HR responses to activation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-D-aspartate (NMDA) receptors in the nucleus ambiguous (NA) are reduced in CIH-exposed rats and that this impairment is associated with degeneration of glutamate receptor (GluR)-immunoreactive NA neurons. Fischer 344 rats (3-4 mo) were exposed to room air (RA) or CIH for 35-50 days (n = 18/group). At the end of the exposures, AMPA (4 pmol, 20 nl) and NMDA (80 pmol, 20 nl) were microinjected into the same location of the left NA (-200 microm to +200 microm relative to caudal end of area postrema; n = 6/group), and HR and arterial blood pressure responses were measured. In addition, brain stem sections at the level of -800, -400, 0, +400, and +800 microm relative to obex were processed for AMPA and NMDA receptor immunohistochemistry. The number of NA neurons expressing AMPA receptors and NMDA receptors (NMDARs) was quantified. Compared with RA, we found that after CIH 1) HR responses to microinjection of AMPA into the left NA were reduced (RA -290 +/- 30 vs. CIH -227 +/- 15 beats/min, P < 0.05); 2) HR responses to microinjection of NMDA into the left NA were reduced (RA -302 +/- 16 vs. CIH -238 +/- 27 beats/min, P < 0.05); and 3) the number of NMDAR1, AMPA GluR1, and AMPA GluR2/3-immunoreactive cells in the NA was reduced (P < 0.05). These results suggest that degeneration of NA neurons expressing GluRs contributes to impaired baroreflex control of HR in rats exposed to CIH.
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Affiliation(s)
- Binbin Yan
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 4000 Central Florida Parkway, Orlando, FL 32816, USA
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