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Habecker BA, Bers DM, Birren SJ, Chang R, Herring N, Kay MW, Li D, Mendelowitz D, Mongillo M, Montgomery JM, Ripplinger CM, Tampakakis E, Winbo A, Zaglia T, Zeltner N, Paterson DJ. Molecular and cellular neurocardiology in heart disease. J Physiol 2024. [PMID: 38778747 DOI: 10.1113/jp284739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/16/2024] [Indexed: 05/25/2024] Open
Abstract
This paper updates and builds on a previous White Paper in this journal that some of us contributed to concerning the molecular and cellular basis of cardiac neurobiology of heart disease. Here we focus on recent findings that underpin cardiac autonomic development, novel intracellular pathways and neuroplasticity. Throughout we highlight unanswered questions and areas of controversy. Whilst some neurochemical pathways are already demonstrating prognostic viability in patients with heart failure, we also discuss the opportunity to better understand sympathetic impairment by using patient specific stem cells that provides pathophysiological contextualization to study 'disease in a dish'. Novel imaging techniques and spatial transcriptomics are also facilitating a road map for target discovery of molecular pathways that may form a therapeutic opportunity to treat cardiac dysautonomia.
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Affiliation(s)
- Beth A Habecker
- Department of Chemical Physiology & Biochemistry, Department of Medicine Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, CA, USA
| | - Susan J Birren
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, MA, USA
| | - Rui Chang
- Department of Neuroscience, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Neil Herring
- Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Dan Li
- Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Johanna M Montgomery
- Department of Physiology and Manaaki Manawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, CA, USA
| | | | - Annika Winbo
- Department of Physiology and Manaaki Manawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Nadja Zeltner
- Departments of Biochemistry and Molecular Biology, Cell Biology, and Center for Molecular Medicine, University of Georgia, Athens, GA, USA
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre and BHF Centre of Research Excellence, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Chen J, Bendowski KT, Bizanti A, Zhang Y, Ma J, Hoover DB, Gozal D, Shivkumar K, Cheng ZJ. Distribution and morphology of calcitonin gene-related peptide (CGRP) innervation in flat mounts of whole rat atria and ventricles. Auton Neurosci 2024; 251:103127. [PMID: 38211380 DOI: 10.1016/j.autneu.2023.103127] [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: 09/18/2023] [Revised: 10/10/2023] [Accepted: 10/19/2023] [Indexed: 01/13/2024]
Abstract
Calcitonin gene-related peptide (CGRP) is widely used as a marker for nociceptive afferent axons. However, the distribution of CGRP-IR axons has not been fully determined in the whole rat heart. Immunohistochemically labeled flat-mounts of the right and left atria and ventricles, and the interventricular septum (IVS) in rats for CGRP were assessed with a Zeiss imager to generate complete montages of the entire atria, ventricles, and septum, and a confocal microscope was used to acquire detailed images of selected regions. We found that 1) CGRP-IR axons extensively innervated all regions of the atrial walls including the sinoatrial node region, auricles, atrioventricular node region, superior/inferior vena cava, left pre-caval vein, and pulmonary veins. 2) CGRP-IR axons formed varicose terminals around individual neurons in some cardiac ganglia but passed through other ganglia without making appositions with cardiac neurons. 3) Varicose CGRP-IR axons innervated the walls of blood vessels. 4) CGRP-IR axons extensively innervated the right/left ventricular walls and IVS. Our data shows the rather ubiquitous distribution of CGRP-IR axons in the whole rat heart at single-cell/axon/varicosity resolution for the first time. This study lays the foundation for future studies to quantify the differences in CGRP-IR axon innervation between sexes, disease models, and species.
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Affiliation(s)
- Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA.
| | - Kohlton T Bendowski
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA.
| | - Ariege Bizanti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | - Yuanyuan Zhang
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | - Jichao Ma
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | - Donald B Hoover
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
| | - David Gozal
- Office of the Dean, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25701, USA
| | - Kalyanam Shivkumar
- Department of Medicine, Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California, Los Angeles, CA 90095, USA
| | - Zixi Jack Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA.
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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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Zhang Y, Bizanti A, Harden SW, Chen J, Bendowski K, Hoover DB, Gozal D, Shivkumar K, Heal M, Tappan S, Cheng ZJ. Topographical mapping of catecholaminergic axon innervation in the flat-mounts of the mouse atria: a quantitative analysis. Sci Rep 2023; 13:4850. [PMID: 37029119 PMCID: PMC10082215 DOI: 10.1038/s41598-023-27727-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 01/06/2023] [Indexed: 04/09/2023] Open
Abstract
The sympathetic nervous system is crucial for controlling multiple cardiac functions. However, a comprehensive, detailed neuroanatomical map of the sympathetic innervation of the heart is unavailable. Here, we used a combination of state-of-the-art techniques, including flat-mount tissue processing, immunohistochemistry for tyrosine hydroxylase (TH, a sympathetic marker), confocal microscopy and Neurolucida 360 software to trace, digitize, and quantitatively map the topographical distribution of the sympathetic postganglionic innervation in whole atria of C57Bl/6 J mice. We found that (1) 4-5 major extrinsic TH-IR nerve bundles entered the atria at the superior vena cava, right atrium (RA), left precaval vein and the root of the pulmonary veins (PVs) in the left atrium (LA). Although these bundles projected to different areas of the atria, their projection fields partially overlapped. (2) TH-IR axon and terminal density varied considerably between different sites of the atria with the greatest density of innervation near the sinoatrial node region (P < 0.05, n = 6). (3) TH-IR axons also innervated blood vessels and adipocytes. (4) Many principal neurons in intrinsic cardiac ganglia and small intensely fluorescent cells were also strongly TH-IR. Our work provides a comprehensive topographical map of the catecholaminergic efferent axon morphology, innervation, and distribution in the whole atria at single cell/axon/varicosity scale that may be used in future studies to create a cardiac sympathetic-brain atlas.
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Affiliation(s)
- Yuanyuan Zhang
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Ariege Bizanti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Scott W Harden
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Kohlton Bendowski
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Donald B Hoover
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - David Gozal
- Department of Child Health and Child Health Research Institute, University of Missouri School of Medicine, Columbia, MO, 65201, USA
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65201, USA
| | - Kalyanam Shivkumar
- Department of Medicine, Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California, Los Angeles, CA, 90095, USA
| | - Maci Heal
- MBF Bioscience, Williston, VT, 05495, USA
| | | | - Zixi Jack Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, BMS Building 20, Room 230, 4110 Libra Drive, Orlando, FL, 32816, USA.
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Scridon A. Autonomic imbalance and atrial ectopic activity-a pathophysiological and clinical view. Front Physiol 2022; 13:1058427. [PMID: 36531175 PMCID: PMC9755506 DOI: 10.3389/fphys.2022.1058427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/22/2022] [Indexed: 09/29/2023] Open
Abstract
The heart is one of the most richly innervated organs and the impact of the complex cardiac autonomic network on atrial electrophysiology and arrhythmogenesis, including on atrial ectopy, is widely recognized. The aim of this review is to discuss the main mechanisms involved in atrial ectopic activity. An overview of the anatomic and physiological aspects of the cardiac autonomic nervous system is provided as well as a discussion of the main pathophysiological pathways linking autonomic imbalance and atrial ectopic activity. The most relevant data on cardiac neuromodulation strategies are emphasized. Unanswered questions and hotspots for future research are also identified.
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Affiliation(s)
- Alina Scridon
- Physiology Department, Center for Advanced Medical and Pharmaceutical Research, University of Medicine, Pharmacy, Science and Technology “George Emil Palade” of Târgu Mureș, Târgu Mureș, Romania
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Zhang D, Tu H, Hu W, Duan B, Zimmerman MC, Li YL. Hydrogen Peroxide Scavenging Restores N-Type Calcium Channels in Cardiac Vagal Postganglionic Neurons and Mitigates Myocardial Infarction-Evoked Ventricular Arrhythmias in Type 2 Diabetes Mellitus. Front Cardiovasc Med 2022; 9:871852. [PMID: 35548411 PMCID: PMC9082497 DOI: 10.3389/fcvm.2022.871852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectiveWithdrawal of cardiac vagal activity is associated with ventricular arrhythmia-related high mortality in patients with type 2 diabetes mellitus (T2DM). Our recent study found that reduced cell excitability of cardiac vagal postganglionic (CVP) neurons is involved in cardiac vagal dysfunction and further exacerbates myocardial infarction (MI)-evoked ventricular arrhythmias and mortality in T2DM. However, the mechanisms responsible for T2DM-impaired cell excitability of CVP neurons remain unclear. This study tested if and how elevation of hydrogen peroxide (H2O2) inactivates CVP neurons and contributes to cardiac vagal dysfunction and ventricular arrhythmogenesis in T2DM.Methods and ResultsRat T2DM was induced by a high-fat diet plus streptozotocin injection. Local in vivo transfection of adenoviral catalase gene (Ad.CAT) successfully induced overexpression of catalase and subsequently reduced cytosolic H2O2 levels in CVP neurons in T2DM rats. Ad.CAT restored protein expression and ion currents of N-type Ca2+ channels and increased cell excitability of CVP neurons in T2DM. Ad.CAT normalized T2DM-impaired cardiac vagal activation, vagal control of ventricular function, and heterogeneity of ventricular electrical activity. Additionally, Ad.CAT not only reduced the susceptibility to ventricular arrhythmias, but also suppressed MI-evoked lethal ventricular arrhythmias such as VT/VF in T2DM.ConclusionsWe concluded that endogenous H2O2 elevation inhibited protein expression and activation of N-type Ca2+ channels and reduced cell excitability of CVP neurons, which further contributed to the withdrawal of cardiac vagal activity and ventricular arrhythmogenesis in T2DM. Our current study suggests that the H2O2-N-type Ca2+ channel signaling axis might be an effective therapeutic target to suppress ventricular arrhythmias in T2DM patients with MI.
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Affiliation(s)
- Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Wenfeng Hu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Bin Duan
- Mary and Dick Holland Regenerative Medicine Program, Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Matthew C. Zimmerman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
- *Correspondence: Yu-Long Li
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Abstract
Much of biology is rhythmical and comprises oscillators that can couple. These have optimized energy efficiency and have been preserved during evolution. The respiratory and cardiovascular systems contain numerous oscillators, and importantly, they couple. This coupling is dynamic but essential for an efficient transmission of neural information critical for the precise linking of breathing and oxygen delivery while permitting adaptive responses to changes in state. The respiratory pattern generator and the neural network responsible for sympathetic and cardiovagal (parasympathetic) tone generation interact at many levels ensuring that cardiac output and regional blood flow match oxygen delivery to the lungs and tissues efficiently. The most classic manifestations of these interactions are respiratory sinus arrhythmia and the respiratory modulation of sympathetic nerve activity. These interactions derive from shared somatic and cardiopulmonary afferent inputs, reciprocal interactions between brainstem networks and inputs from supra-pontine regions. Disrupted respiratory-cardiovascular coupling can result in disease, where it may further the pathophysiological sequelae and be a harbinger of poor outcomes. This has been well documented by diminished respiratory sinus arrhythmia and altered respiratory sympathetic coupling in animal models and/or patients with myocardial infarction, heart failure, diabetes mellitus, and neurological disorders as stroke, brain trauma, Parkinson disease, or epilepsy. Future research needs to assess the therapeutic potential for ameliorating respiratory-cardiovascular coupling in disease.
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Affiliation(s)
- James P Fisher
- Manaaki Manawa-The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
| | - Tymoteusz Zera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Julian F R Paton
- Manaaki Manawa-The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand.
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Hu W, Zhang D, Tu H, Li YL. Reduced Cell Excitability of Cardiac Postganglionic Parasympathetic Neurons Correlates With Myocardial Infarction-Induced Fatal Ventricular Arrhythmias in Type 2 Diabetes Mellitus. Front Neurosci 2021; 15:721364. [PMID: 34483832 PMCID: PMC8416412 DOI: 10.3389/fnins.2021.721364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/30/2021] [Indexed: 01/09/2023] Open
Abstract
Objective Withdrawal of cardiac vagal activity is considered as one of the important triggers for acute myocardial infarction (MI)-induced ventricular arrhythmias in type 2 diabetes mellitus (T2DM). Our previous study demonstrated that cell excitability of cardiac parasympathetic postganglionic (CPP) neurons was reduced in T2DM rats. This study investigated whether cell excitability of CPP neurons is associated with cardiac vagal activity and MI-induced ventricular arrhythmias in T2DM rats. Methods Rat T2DM was induced by a high-fat diet plus streptozotocin injection. MI-evoked ventricular arrhythmia was achieved by surgical ligation of the left anterior descending coronary artery. Twenty-four-hour, continuous ECG recording was used to quantify ventricular arrhythmic events and heart rate variability (HRV) in conscious rats. The power spectral analysis of HRV was used to evaluate autonomic function. Cell excitability of CPP neurons was measured by the whole-cell patch-clamp technique. Results Twenty-four-hour ECG data demonstrated that MI-evoked fatal ventricular arrhythmias are more severe in T2DM rats than that in sham rats. In addition, the Kaplan-Meier analysis demonstrated that the survival rate over 2 weeks after MI is significantly lower in T2DM rats (15% in T2DM+MI) compared to sham rats (75% in sham+MI). The susceptibility to ventricular tachyarrhythmia elicited by programmed electrical stimulation was higher in anesthetized T2DM+MI rats than that in rats with MI or T2DM alone (7.0 ± 0.58 in T2DM+MI group vs. 3.5 ± 0.76 in sham+MI). Moreover, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of increase of left ventricular pressure (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in T2DM rats. Furthermore, T2DM increased heterogeneity of ventricular electrical activities and reduced cardiac parasympathetic activity and cell excitability of CPP neurons (current threshold-inducing action potentials being 62 ± 3.3 pA in T2DM rats without MI vs. 27 ± 1.9 pA in sham rats without MI). However, MI did not alter vagal control of the ventricular function and CPP neuronal excitability, although it also induced cardiac autonomic dysfunction and enhanced heterogeneity of ventricular electrical activities. Conclusion The reduction of CPP neuron excitability is involved in decreased cardiac vagal function, including cardiac parasympathetic activity and vagal control of ventricular function, which is associated with MI-induced high mortality and malignant ventricular arrhythmias in T2DM.
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Affiliation(s)
- Wenfeng Hu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States.,Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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Harper AA, Adams DJ. Electrical properties and synaptic transmission in mouse intracardiac ganglion neurons in situ. Physiol Rep 2021; 9:e15056. [PMID: 34582125 PMCID: PMC8477906 DOI: 10.14814/phy2.15056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/25/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022] Open
Abstract
The intrinsic cardiac nervous system represents the final site of signal integration for neurotransmission to the myocardium to enable local control of cardiac performance. The electrophysiological characteristics and ganglionic transmission of adult mouse intrinsic cardiac ganglion (ICG) neurons were investigated using a whole-mount ganglion preparation of the excised right atrial ganglion plexus and intracellular microelectrode recording techniques. The passive and active electrical properties of ICG neurons and synaptic transmission including synaptic response strength and efficacy as a function of stimulation frequency were examined. The resting membrane potential and input resistance of ICG neurons were -47.9 ± 4.0 mV and 197.2 ± 81.5 MΩ, respectively. All neurons had somatic action potentials with overshoots of >+15 mV and after-hyperpolarizations having an average of 10 mV amplitude and ~45 ms half duration. Phasic discharge activities were recorded from the majority of neurons studied and several types of excitatory synaptic responses were recorded following inputs from the vagus or interganglionic nerve trunk(s). Most postganglionic neurons (>75%) received a strong, suprathreshold synaptic input and reliably followed high-frequency repetitive nerve stimulation up to at least 50 Hz. Nerve-evoked synaptic transmission was blocked by extracellular Cd2+ , ω-conotoxin CVIE, or α-conotoxin RegIIA, a selective α3-containing nicotinic acetylcholine receptor antagonist. Synaptic transmission and the electrical properties of murine ICG neurons contribute to the pattern of discharge which regulates chronotropic, dromotropic, and inotropic elements of cardiac function.
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Affiliation(s)
- Alexander A. Harper
- Illawarra Health and Medical Research Institute (IHMRI)University of WollongongWollongongNew South WalesAustralia
| | - David J. Adams
- Illawarra Health and Medical Research Institute (IHMRI)University of WollongongWollongongNew South WalesAustralia
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Leung C, Robbins S, Moss A, Heal M, Osanlouy M, Christie R, Farahani N, Monteith C, Chen J, Hunter P, Tappan S, Vadigepalli R, Cheng Z(J, Schwaber JS. 3D single cell scale anatomical map of sex-dependent variability of the rat intrinsic cardiac nervous system. iScience 2021; 24:102795. [PMID: 34355144 PMCID: PMC8324857 DOI: 10.1016/j.isci.2021.102795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/05/2021] [Accepted: 06/24/2021] [Indexed: 02/01/2023] Open
Abstract
We developed and analyzed a single cell scale anatomical map of the rat intrinsic cardiac nervous system (ICNS) across four male and three female hearts. We find the ICNS has a reliable structural organizational plan across individuals that provide the foundation for further analyses of the ICNS in cardiac function and disease. The distribution of the ICNS was evaluated by 3D visualization and data-driven clustering. The pattern, distribution, and clustering of ICNS neurons across all male and female rat hearts is highly conserved, demonstrating a coherent organizational plan where distinct clusters of neurons are consistently localized. Female hearts had fewer neurons, lower packing density, and slightly reduced distribution, but with identical localization. We registered the anatomical data from each heart to a geometric scaffold, normalizing their 3D coordinates for standardization of common anatomical planes and providing a path where multiple experimental results and data types can be integrated and compared.
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Affiliation(s)
- Clara Leung
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Shaina Robbins
- Daniel Baugh Institute of Functional Genomics/Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Alison Moss
- Daniel Baugh Institute of Functional Genomics/Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Mahyar Osanlouy
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Richard Christie
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | | | - Jin Chen
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Peter Hunter
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | - Rajanikanth Vadigepalli
- Daniel Baugh Institute of Functional Genomics/Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Zixi (Jack) Cheng
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - James S. Schwaber
- Daniel Baugh Institute of Functional Genomics/Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Abstract
The electromechanical function of the heart involves complex, coordinated activity over time and space. Life-threatening cardiac arrhythmias arise from asynchrony in these space-time events; therefore, therapies for prevention and treatment require fundamental understanding and the ability to visualize, perturb and control cardiac activity. Optogenetics combines optical and molecular biology (genetic) approaches for light-enabled sensing and actuation of electrical activity with unprecedented spatiotemporal resolution and parallelism. The year 2020 marks a decade of developments in cardiac optogenetics since this technology was adopted from neuroscience and applied to the heart. In this Review, we appraise a decade of advances that define near-term (immediate) translation based on all-optical electrophysiology, including high-throughput screening, cardiotoxicity testing and personalized medicine assays, and long-term (aspirational) prospects for clinical translation of cardiac optogenetics, including new optical therapies for rhythm control. The main translational opportunities and challenges for optogenetics to be fully embraced in cardiology are also discussed.
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12
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Fedele L, Brand T. The Intrinsic Cardiac Nervous System and Its Role in Cardiac Pacemaking and Conduction. J Cardiovasc Dev Dis 2020; 7:jcdd7040054. [PMID: 33255284 PMCID: PMC7712215 DOI: 10.3390/jcdd7040054] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022] Open
Abstract
The cardiac autonomic nervous system (CANS) plays a key role for the regulation of cardiac activity with its dysregulation being involved in various heart diseases, such as cardiac arrhythmias. The CANS comprises the extrinsic and intrinsic innervation of the heart. The intrinsic cardiac nervous system (ICNS) includes the network of the intracardiac ganglia and interconnecting neurons. The cardiac ganglia contribute to the tight modulation of cardiac electrophysiology, working as a local hub integrating the inputs of the extrinsic innervation and the ICNS. A better understanding of the role of the ICNS for the modulation of the cardiac conduction system will be crucial for targeted therapies of various arrhythmias. We describe the embryonic development, anatomy, and physiology of the ICNS. By correlating the topography of the intracardiac neurons with what is known regarding their biophysical and neurochemical properties, we outline their physiological role in the control of pacemaker activity of the sinoatrial and atrioventricular nodes. We conclude by highlighting cardiac disorders with a putative involvement of the ICNS and outline open questions that need to be addressed in order to better understand the physiology and pathophysiology of the ICNS.
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Affiliation(s)
- Laura Fedele
- Correspondence: (L.F.); (T.B.); Tel.: +44-(0)-207-594-6531 (L.F.); +44-(0)-207-594-8744 (T.B.)
| | - Thomas Brand
- Correspondence: (L.F.); (T.B.); Tel.: +44-(0)-207-594-6531 (L.F.); +44-(0)-207-594-8744 (T.B.)
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13
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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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14
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Moreno A, Endicott K, Skancke M, Dwyer MK, Brennan J, Efimov IR, Trachiotis G, Mendelowitz D, Kay MW. Sudden Heart Rate Reduction Upon Optogenetic Release of Acetylcholine From Cardiac Parasympathetic Neurons in Perfused Hearts. Front Physiol 2019; 10:16. [PMID: 30745877 PMCID: PMC6360159 DOI: 10.3389/fphys.2019.00016] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 01/10/2019] [Indexed: 11/13/2022] Open
Abstract
The balance of sympathetic and parasympathetic tone provides exquisite control of heart rate and contractility and has also been shown to modulate coronary flow and inflammation. Understanding how autonomic balance is altered by cardiac disease is an active area of research, and developing new ways to control this balance provides insights into disease therapies. However, achieving acute neuron-specific stimulation of autonomic neurons can be difficult in experiments that measure the acute effects of nerve stimulation on the heart. Conventional electrical and pharmacological approaches can be spatially and temporally non-selective. Cell-specific expression of light-activated channels (channelrhodopsin, ChR2) is a powerful approach that enables control of the timing and distribution of cellular stimulation using light. We present such an optogenetic approach where parasympathetic cardiac neurons are selectively photoactivated at high temporal precision to initiate cholinergic-mediated slowing of heart rate. Mice were crossbred to express ChR2 in peripheral cholinergic neurons using Cre-Lox recombination driven by a choline acetyltransferase (ChAT) promoter. Hearts from adult mice were excised, perfused, and the epicardium was illuminated (peak 460–465 nm) to photoactivate ChR2. In one set of studies, hearts were illuminated using a large-field LED light source. In other studies, a micro LED was placed on the right atrium to selectively illuminate the junction of the superior vena cava (SVC) and right atrium. The ECG was acquired before, during, and after tissue illumination to measure changes in heart rate. Upon illumination, hearts exhibited sudden and dramatic reductions in heart rate with restoration of normal heart rate after cessation of illumination. Delays in atrioventricular conduction were also observed. Heart rate reductions at the highest irradiance levels were similar to heart rate reductions caused by application of bethanechol (10 μM) or acetylcholine (800 μM). Atropine (50 nM) completely blocked the effect of ChR2 photoactivation, confirming cholinergic mediation. Optogenetic activation of intrinsic parasympathetic neurons reduced heart rate in an immediate, dose-dependent fashion, resembling the slowing of sinus rate in response to acetylcholine. Our results demonstrate a new approach for controlling parasympathetic modulation of cardiac function by selectively activating the endogenous release of acetylcholine from intrinsic cardiac cholinergic neurons. Key Message: Optogenetic photoactivation of intrinsic cardiac neurons provides immediate, tissue-specific stimulation with minimal cross-reactivity. Our results demonstrate that selective expression of channelrhodopsin within cardiac cholinergic neurons enables photoactivated release of acetylcholine, thereby instantaneously slowing sinus rate and altering atrioventricular conduction. This provides for in-depth examination of the endogenous interplay between cardiac autonomic neurons and the functional outcomes of downstream post-synaptic receptor activation.
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Affiliation(s)
- Angel Moreno
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | - Kendal Endicott
- Division of Cardiothoracic Surgery, Veterans Affairs Medical Center, Washington, DC, United States
| | - Matthew Skancke
- Division of Cardiothoracic Surgery, Veterans Affairs Medical Center, Washington, DC, United States
| | - Mary Kate Dwyer
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | - Jaclyn Brennan
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | - Igor R Efimov
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | - Gregory Trachiotis
- Division of Cardiothoracic Surgery, Veterans Affairs Medical Center, Washington, DC, United States
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC, United States
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
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15
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Gourine AV, Ackland GL. Cardiac Vagus and Exercise. Physiology (Bethesda) 2019; 34:71-80. [PMID: 30540229 PMCID: PMC6383634 DOI: 10.1152/physiol.00041.2018] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 01/09/2023] Open
Abstract
Lower resting heart rate and high autonomic vagal activity are strongly associated with superior exercise capacity, maintenance of which is essential for general well-being and healthy aging. Recent evidence obtained in experimental studies using the latest advances in molecular neuroscience, combined with human exercise physiology, physiological modeling, and genomic data suggest that the strength of cardiac vagal activity causally determines our ability to exercise.
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Affiliation(s)
- Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London , London , United Kingdom
| | - Gareth L Ackland
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London , London , United Kingdom
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16
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Zhang D, Tu H, Cao L, Zheng H, Muelleman RL, Wadman MC, Li YL. Reduced N-Type Ca 2+ Channels in Atrioventricular Ganglion Neurons Are Involved in Ventricular Arrhythmogenesis. J Am Heart Assoc 2018; 7:JAHA.117.007457. [PMID: 29335317 PMCID: PMC5850164 DOI: 10.1161/jaha.117.007457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Background Attenuated cardiac vagal activity is associated with ventricular arrhythmogenesis and related mortality in patients with chronic heart failure. Our recent study has shown that expression of N‐type Ca2+ channel α‐subunits (Cav2.2‐α) and N‐type Ca2+ currents are reduced in intracardiac ganglion neurons from rats with chronic heart failure. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Ventricular myocardium receives projection of neuronal terminals only from the AVG. In this study we tested whether a decrease in N‐type Ca2+ channels in AVG neurons contributes to ventricular arrhythmogenesis. Methods and Results Lentiviral Cav2.2‐α shRNA (2 μL, 2×107 pfu/mL) or scrambled shRNA was in vivo transfected into rat AVG neurons. Nontransfected sham rats served as controls. Using real‐time single‐cell polymerase chain reaction and reverse‐phase protein array, we found that in vivo transfection of Cav2.2‐α shRNA decreased expression of Cav2.2‐α mRNA and protein in rat AVG neurons. Whole‐cell patch‐clamp data showed that Cav2.2‐α shRNA reduced N‐type Ca2+ currents and cell excitability in AVG neurons. The data from telemetry electrocardiographic recording demonstrated that 83% (5 out of 6) of conscious rats with Cav2.2‐α shRNA transfection had premature ventricular contractions (P<0.05 versus 0% of nontransfected sham rats or scrambled shRNA‐transfected rats). Additionally, an index of susceptibility to ventricular arrhythmias, inducibility of ventricular arrhythmias evoked by programmed electrical stimulation, was higher in rats with Cav2.2‐α shRNA transfection compared with nontransfected sham rats and scrambled shRNA‐transfected rats. Conclusions A decrease in N‐type Ca2+ channels in AVG neurons attenuates vagal control of ventricular myocardium, thereby initiating ventricular arrhythmias.
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Affiliation(s)
- Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Liang Cao
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE.,Department of Cardiac surgery, Second Xiangya Hospital, Central South University, Changsha, China
| | - Hong Zheng
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE
| | - Robert L Muelleman
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Michael C Wadman
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE .,Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE
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17
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Atrial fibrillation: Neurogenic or myogenic? Arch Cardiovasc Dis 2018; 111:59-69. [DOI: 10.1016/j.acvd.2017.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/07/2017] [Accepted: 11/13/2017] [Indexed: 01/08/2023]
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18
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Machhada A, Marina N, Korsak A, Stuckey DJ, Lythgoe MF, Gourine AV. Origins of the vagal drive controlling left ventricular contractility. J Physiol 2016; 594:4017-30. [PMID: 26940639 PMCID: PMC4945717 DOI: 10.1113/jp270984] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 03/01/2016] [Indexed: 01/22/2023] Open
Abstract
Key points The strength, functional significance and origins of parasympathetic innervation of the left ventricle remain controversial. This study tested the hypothesis that parasympathetic control of left ventricular contractility is provided by vagal preganglionic neurones of the dorsal motor nucleus (DVMN). Under β‐adrenoceptor blockade combined with spinal cord (C1) transection (to remove sympathetic influences), systemic administration of atropine increased left ventricular contractility in rats anaesthetized with urethane, confirming the existence of a tonic inhibitory muscarinic influence on cardiac inotropy. Increased left ventricular contractility in anaesthetized rats was observed when DVMN neurones were silenced. Functional neuroanatomical mapping revealed that vagal preganglionic neurones that have an impact on left ventricular contractility are located in the caudal region of the left DVMN. These neurones provide functionally significant parasympathetic control of left ventricular inotropy.
Abstract The strength, functional significance and origins of direct parasympathetic innervation of the left ventricle (LV) remain controversial. In the present study we used an anaesthetized rat model to first confirm the presence of tonic inhibitory vagal influence on LV inotropy. Using genetic neuronal targeting and functional neuroanatomical mapping we tested the hypothesis that parasympathetic control of LV contractility is provided by vagal preganglionic neurones located in the dorsal motor nucleus (DVMN). It was found that under systemic β‐adrenoceptor blockade (atenolol) combined with spinal cord (C1) transection (to remove sympathetic influences), intravenous administration of atropine increases LV contractility in rats anaesthetized with urethane, but not in animals anaesthetized with pentobarbital. Increased LV contractility in rats anaesthetized with urethane was also observed when DVMN neurones targeted bilaterally to express an inhibitory Drosophila allatostatin receptor were silenced by application of an insect peptide allatostatin. Microinjections of glutamate and muscimol to activate or inhibit neuronal cell bodies in distinct locations along the rostro‐caudal extent of the left and right DVMN revealed that vagal preganglionic neurones, which have an impact on LV contractility, are located in the caudal region of the left DVMN. Changes in LV contractility were only observed when this subpopulation of DVMN neurones was activated or inhibited. These data confirm the existence of a tonic inhibitory muscarinic influence on LV contractility. Activity of a subpopulation of DVMN neurones provides functionally significant parasympathetic control of LV contractile function. The strength, functional significance and origins of parasympathetic innervation of the left ventricle remain controversial. This study tested the hypothesis that parasympathetic control of left ventricular contractility is provided by vagal preganglionic neurones of the dorsal motor nucleus (DVMN). Under β‐adrenoceptor blockade combined with spinal cord (C1) transection (to remove sympathetic influences), systemic administration of atropine increased left ventricular contractility in rats anaesthetized with urethane, confirming the existence of a tonic inhibitory muscarinic influence on cardiac inotropy. Increased left ventricular contractility in anaesthetized rats was observed when DVMN neurones were silenced. Functional neuroanatomical mapping revealed that vagal preganglionic neurones that have an impact on left ventricular contractility are located in the caudal region of the left DVMN. These neurones provide functionally significant parasympathetic control of left ventricular inotropy.
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Affiliation(s)
- Asif Machhada
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK.,UCL Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, WC1E 6DD, UK
| | - Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Daniel J Stuckey
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, WC1E 6DD, UK
| | - Mark F Lythgoe
- UCL Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, WC1E 6DD, UK
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
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19
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Ripplinger CM, Noujaim SF, Linz D. The nervous heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 120:199-209. [PMID: 26780507 DOI: 10.1016/j.pbiomolbio.2015.12.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/29/2015] [Accepted: 12/31/2015] [Indexed: 12/23/2022]
Abstract
Many cardiac electrophysiological abnormalities are accompanied by autonomic nervous system dysfunction. Here, we review mechanisms by which the cardiac nervous system controls normal and abnormal excitability and may contribute to atrial and ventricular tachyarrhythmias. Moreover, we explore the potential antiarrhythmic and/or arrhythmogenic effects of modulating the autonomic nervous system by several strategies, including ganglionated plexi ablation, vagal and spinal cord stimulations, and renal sympathetic denervation as therapies for atrial and ventricular arrhythmias.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA.
| | - Sami F Noujaim
- Molecular Pharmacology and Physiology, University of South Florida, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA.
| | - Dominik Linz
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, 66421 Homburg, Saar, Germany.
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20
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Berg T. Voltage-Sensitive K(+) Channels Inhibit Parasympathetic Ganglion Transmission and Vagal Control of Heart Rate in Hypertensive Rats. Front Neurol 2015; 6:260. [PMID: 26696959 PMCID: PMC4672051 DOI: 10.3389/fneur.2015.00260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 11/25/2015] [Indexed: 01/19/2023] Open
Abstract
Parasympathetic withdrawal plays an important role in the autonomic dysfunctions in hypertension. Since hyperpolarizing, voltage-sensitive K+ channels (KV) hamper transmitter release, elevated KV-activity may explain the disturbed vagal control of heart rate (HR) in hypertension. Here, the KV inhibitor 3,4-diaminopyridine was used to demonstrate the impact of KV on autonomic HR control. Cardiac output and HR were recorded by a flow probe on the ascending aorta in anesthetized, normotensive (WKY), and spontaneously hypertensive rats (SHR), and blood pressure by a femoral artery catheter. 3,4-diaminopyridine induced an initial bradycardia, which was greater in SHR than in WKY, followed by sustained tachycardia in both strains. The initial bradycardia was eliminated by acetylcholine synthesis inhibitor (hemicholinium-3) and nicotinic receptor antagonist/ganglion blocker (hexamethonium), and reversed to tachycardia by muscarinic receptor (mAchR) antagonist (atropine). The latter was abolished by sympatho-inhibition (reserpine). Reserpine also eliminated the late, 3,4-diaminopyridine-induced tachycardia in WKY, but induced a sustained atropine-sensitive bradycardia in SHR. Inhibition of the parasympathetic component with hemicholinium-3, hexamethonium, or atropine enhanced the late tachycardia in SHR, whereas hexamethonium reduced the tachycardia in WKY. In conclusion, 3,4-diaminopyridine-induced acetylcholine release, and thus enhanced parasympathetic ganglion transmission, with subsequent mAchR activation and bradycardia. 3,4-diaminopyridine also activated tachycardia, initially by enhancing sympathetic ganglion transmission, subsequently by activation of norepinephrine release from sympathetic nerve terminals. The 3,4-diaminopyridine-induced parasympathetic activation was stronger and more sustained in SHR, demonstrating an enhanced inhibitory control of KV on parasympathetic ganglion transmission. This enhanced KV activity may explain the dysfunctional vagal HR control in SHR.
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Affiliation(s)
- Torill Berg
- Division of Physiology, Department of Molecular Medicine, Institute for Basic Medical Sciences, University of Oslo , Oslo , Norway
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21
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Abstract
Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur.
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Affiliation(s)
- Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas Marian University College of Osteopathic Medicine, Indianapolis, Indiana
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22
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Li L, Hatcher JT, Hoover DB, Gu H, Wurster RD, Cheng ZJ. Distribution and morphology of calcitonin gene-related peptide and substance P immunoreactive axons in the whole-mount atria of mice. Auton Neurosci 2014; 181:37-48. [PMID: 24433968 PMCID: PMC10506417 DOI: 10.1016/j.autneu.2013.12.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 11/17/2013] [Accepted: 12/17/2013] [Indexed: 11/30/2022]
Abstract
The murine model has been used to investigate the role of cardiac sensory axons in various disease states. However, the distribution and morphological structures of cardiac nociceptive axons in normal murine tissues have not yet been well characterized. In this study, whole-mount atria from FVB mice were processed with calcitonin gene-related peptide (CGRP) and substance P (SP) primary antibodies followed by secondary antibodies, and then examined using confocal microscopy. We found: 1) Large CGRP-IR axon bundles entered the atria with the major veins, and these large bundles bifurcated into small bundles and single axons that formed terminal end-nets and free endings in the epicardium. Varicose CGRP-IR axons had close contacts with muscle fibers, and some CGRP-IR axons formed varicosities around principle neurons (PNs) within intrinsic cardiac ganglia (ICGs). 2) SP-IR axons also were found in the same regions of the atria, attached to veins, and within cardiac ganglia. Similar to CGRP-IR axons, these SP-IR axons formed terminal end-nets and free endings in the atrial epicardium and myocardium. Within ICGs, SP-IR axons formed varicose endings around PNs. However, SP-IR nerve fibers were less abundant than CGRP-IR fibers in the atria. 3) None of the PNs were CGRP-IR or SP-IR. 4) CGRP-IR and SP-IR often colocalized in terminal varicosities around PNs. Collectively, our data document the distribution pattern and morphology of CGRP-IR and SP-IR axons and terminals in different regions of the atria. This knowledge provides useful information for CGRP-IR and SP-IR axons that can be referred to in future studies of pathological remodeling.
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Affiliation(s)
- Liang Li
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, United States
| | - Jeffrey T Hatcher
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, United States
| | - Donald B Hoover
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
| | - He Gu
- Department of Anesthesia, University of Iowa Hospital and Clinics, Iowa City, IA 52242, United States
| | - Robert D Wurster
- Department of Physiology, Loyola University, Stritch School of Medicine, Maywood, IL 60153, United States
| | - Zixi Jack Cheng
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, United States.
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23
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Xie X, Lee SW, Johnson C, Ippolito J, KenKnight BH, Tolkacheva EG. Intermittent vagal nerve stimulation alters the electrophysiological properties of atrium in the myocardial infarction rat model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2014; 2014:1575-1578. [PMID: 25570272 DOI: 10.1109/embc.2014.6943904] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Intermittent vagal nerve stimulation (VNS) has emerged as a potential therapy to treat cardiovascular diseases by delivering electrical stimulation to the vagus nerves. The purpose of this study was to investigate the electrophysiological changes in the atrium resulting from long-term intermittent VNS therapy in the chronic myocardial infarction (MI) rat model. MI was induced via left anterior descending coronary artery (LAD) ligation in male Sprague-Dawley rats, randomized into two groups: MI (implanted with nonfunctional VNS stimulators) and MI-VNS (implanted with functional VNS stimulators and received chronic intermittent VNS treatment) groups. Further, a sham group was used as control in which MI was not performed and received nonfunctional VNS stimulators. At 12 weeks, optical mapping of right atrium (RA) of sinus rhythm was performed. Our results demonstrated that chronic MI changed the electrical properties of the atrium action potentials and resulted in reduced action potential duration at 50% (APD50) and 80% (APD80) repolarization. Chronic right cervical VNS restored the APD back to healthy heart APD values. Additionally, APD heterogeneity index increased as a result of the chronic MI. Chronic VNS was not found to alter this increase. By calculating PR intervals from weekly ECG recordings of anaesthetized rats, we demonstrated that chronic MI and intermittent VNS did not affect the AV conduction time from the atria to the ventricles. From our study, we conclude the MI decreased the APD and increased APD spatial dispersion. VNS increased the APD back to healthy normal values but did change the APD spatial dispersion and the electrical conduction in the RA.
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24
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Sampaio KN, Mauad H, Michael Spyer K, Ford TW. Chronotropic and dromotropic responses to localized glutamate microinjections in the rat nucleus ambiguus. Brain Res 2013; 1542:93-103. [PMID: 24177045 PMCID: PMC3894684 DOI: 10.1016/j.brainres.2013.10.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/09/2013] [Accepted: 10/18/2013] [Indexed: 01/19/2023]
Abstract
The cardioinhibitory effects of cardiac vagal motoneurons (CVMs) are mediated by activation of postganglionic neurons in the epicardial ganglia which have been shown to exert functionally selective effects on heart rate and atrioventricular conduction in the rat. Here we investigate whether CVMs producing these responses may occupy different rostrocaudal positions within the nucleus ambiguus. Excitation of CVMs was attempted by microinjections of glutamate into the nucleus ambiguus of an arterially perfused preparation in a grid extending over 2 mm in the rostrocaudal plane using the obex as a reference point. Microinjections were paired, one made during pacing to measure changes in atrioventricular conduction (P-R interval) independent of changes in heart rate and the other looking for changes in heart period (P-P interval) un-paced. Although evidence of a differential distribution was found in 7 cases, in the majority (13/20), sites producing maximal effects on both variables coincided. Maximal changes in atrioventricular conduction resulted from more rostral sites in 6 cases and from a more caudal site in only one. Overall, the ratio of the change in atrioventricular conduction to the change in heart rate for a given site was significantly greater 1 mm rostral to the obex than at either end of the test grid. We conclude that while CVMs controlling atrioventricular conduction are distributed with a peak somewhat rostral to those controlling heart rate in a number of animals, there is a significant overlap and much greater variability in this distribution in the rat than in cats and dogs. A reduced, perfused preparation of the rat heart and brain stem was employed. Microinjections of glutamate were made into the nucleus ambiguus. Resulting falls in heart rate and A–V conduction were measured from the ECG. A partial functional vagal efferent localization in this nucleus is described. Considerable inter-animal variability and overlap was found in this localization.
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Affiliation(s)
- Karla N Sampaio
- Division of Biosciences, Faculty of Life Sciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Hélder Mauad
- Division of Biosciences, Faculty of Life Sciences, University College London, Gower Street, London WC1E 6BT, UK
| | - K Michael Spyer
- Division of Biosciences, Faculty of Life Sciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Timothy W Ford
- Division of Biosciences, Faculty of Life Sciences, University College London, Gower Street, London WC1E 6BT, UK.
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Abstract
There is continuing belief that cardiac parasympathetic postganglionic fibres are sparse or absent from the ventricles. This review of the literature shows that the supposition is a myth. Early studies considered that fine silver-stained fibres coursing amongst ventricle myocardial cells were most likely cardiac parasympathetic postganglionic fibres. The conclusions were later supported by acetyl cholinesterase staining using a method that appeared not to be associated with noradrenaline nerve fibres. The conclusion is critically examined in the light of several recent histological studies using the acetyl cholinesterase method and also a more definitive technique (CHAT), that suggest a widespread location of parasympathetic ganglia and a relatively dense parasympathetic innervation of ventricular muscle in a range of mammals including man. The many studies demonstrating acetylcholine release in the ventricle on vagal nerve stimulation and a high density of acetylcholine M2 receptors is in accord with this as are tests of ventricular performance from many physiological studies. Selective control of cardiac functions by anatomically segregated parasympathetic ganglia is discussed. It is argued that the influence of vagal stimulation on ventricular myocardial action potential refractory period, duration, force and rhythm is evidence that vagal fibres have close apposition to myocardial fibres. This is supported by clear evidence of accentuated antagonism between sympathetic activity and vagal activity in the ventricle and also by direct effects of vagal activity independent of sympathetic activity. The idea of differential control of atrial and ventricular physiology by vagal C and vagal B preganglionic fibres is examined as well as differences in chemical phenotypes and their function. The latter is reflected in medullary and supramedullary control. Reference is made to the importance of this knowledge to understanding the normal physiology of cardiac autonomic control and significance to pathology.
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Affiliation(s)
- J H Coote
- J. H. Coote: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK.
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26
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Pauza DH, Saburkina I, Rysevaite K, Inokaitis H, Jokubauskas M, Jalife J, Pauziene N. Neuroanatomy of the murine cardiac conduction system: a combined stereomicroscopic and fluorescence immunohistochemical study. Auton Neurosci 2013; 176:32-47. [PMID: 23403121 DOI: 10.1016/j.autneu.2013.01.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 10/27/2022]
Abstract
The mouse heart is a popular model to study the function and autonomic control of the specialized cardiac conduction system (CCS). However, the precise identity and anatomical distribution of the intrinsic cardiac nerves that modulate the function of the mouse CCS have not been adequately studied. We aimed at determining the organization and distribution of the intrinsic cardiac nerves that supply the CCS of the mouse. In whole mouse heart preparations, intrinsic neural structures were revealed by histochemical staining for acetylcholinesterase (AChE). Adrenergic, cholinergic and peptidergic neural components were identified, respectively, by immunohistochemical labeling for tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), calcitonin gene related peptide (CGRP), substance P (SP), and protein gene product 9.5 (PGP 9.5). Myocytes of the CCS were identified by immunolabeling of hyperpolarization activated cyclic nucleotide-gated potassium channel 4 (HCN4). In addition, the presence of CCS myocytes in atypical locations was verified using fluorescent immunohistochemistry performed on routine paraffin sections. The results demonstrate that four microscopic epicardial nerves orientated toward the sinuatrial nodal (SAN) region derive from both the dorsal right atrial and right ventral nerve subplexuses. The atrioventricular nodal (AVN) region is typically supplied by a single intrinsic nerve derived from the left dorsal nerve subplexus at the posterior interatrial groove. SAN myocytes positive for HCN4 were widely distributed both on the medial, anterior, lateral and even posterior sides of the root of the right cranial (superior caval) vein. The distribution of HCN4-positive myocytes in the AVN region was also wider than previously considered. HCN4-positive cells and thin slivers of the AVN extended to the roots of the ascending aorta, posteriorly to the orifice of the coronary sinus, and even along both atrioventricular rings. Notwithstanding the fact that cholinergic nerve fibers and axons clearly predominate in the mouse CCS, adrenergic nerve fibers and axons are abundant therein as well. Altogether, these results provide new insight into the anatomical basis of the neural control of the mouse CCS.
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Affiliation(s)
- Dainius H Pauza
- Institute of Anatomy, Faculty of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania.
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27
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Liu J, Tu H, Zheng H, Zhang L, Tran TP, Muelleman RL, Li YL. Alterations of calcium channels and cell excitability in intracardiac ganglion neurons from type 2 diabetic rats. Am J Physiol Cell Physiol 2011; 302:C1119-27. [PMID: 22189553 DOI: 10.1152/ajpcell.00315.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Clinical study has demonstrated that patients with type 2 diabetes with attenuated arterial baroreflex have higher mortality rate compared with those without arterial baroreflex dysfunction. As a final pathway for the neural control of the cardiac function, functional changes of intracardiac ganglion (ICG) neurons might be involved in the attenuated arterial baroreflex in the type 2 diabetes mellitus (T2DM). Therefore, we measured the ICG neuron excitability and Ca(2+) channels in the sham and T2DM rats. T2DM was induced by a combination of both high-fat diet and low-dose streptozotocin (STZ, 30 mg/kg ip) injection. After 12-14 wk of the above treatment, the T2DM rats presented hyperglycemia, hyperlipidemia, and insulin resistance but no hyperinsulinemia, which closely mimicked the clinical features of the patients with T2DM. Data from immunofluorescence staining showed that L, N, P/Q, and R types of Ca(2+) channels were expressed in the ICG neurons, but only protein expression of N-type Ca(2+) channels was decreased in the ICG neurons from T2DM rats. Using whole cell patch-clamp technique, we found that T2DM significantly reduced the Ca(2+) currents and cell excitability in the ICG neurons. ω-Conotoxin GVIA (a specific N-type Ca(2+) channel blocker, 1 μM) lowered the Ca(2+) currents and cell excitability toward the same level in sham and T2DM rats. These results indicate that the decreased N-type Ca(2+) channels contribute to the suppressed ICG neuron excitability in T2DM rats. From this study, we think high-fat diet/STZ injection-induced T2DM might be an appropriate animal model to test the cellular and molecular mechanisms of cardiovascular autonomic dysfunction.
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Affiliation(s)
- Jinxu Liu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, 68198-5850, USA
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McAllen RM, Salo LM, Paton JFR, Pickering AE. Processing of central and reflex vagal drives by rat cardiac ganglion neurones: an intracellular analysis. J Physiol 2011; 589:5801-18. [PMID: 22005679 DOI: 10.1113/jphysiol.2011.214320] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cardiac vagal tone is an important indicator of cardiovascular health, and its loss is an independent risk factor for arrhythmias and mortality. Several studies suggest that this loss of vagal tone can occur at the cardiac ganglion but the factors affecting ganglionic transmission in vivo are poorly understood. We have employed a novel approach allowing intracellular recordings from functionally connected cardiac vagal ganglion cells in the working heart-brainstem preparation. The atria were stabilised in situ preserving their central neural connections, and ganglion cells (n = 32) were impaled with sharp microelectrodes. Cardiac ganglion cells with vagal synaptic inputs (spontaneous, n = 10; or electrically evoked from the vagus, n = 3) were identified as principal neurones and showed tonic firing responses to current injected to their somata. Cells lacking vagal inputs (n = 19, presumed interneurones) were quiescent but showed phasic firing responses to depolarising current. In principal cells the ongoing action potentials and EPSPs exhibited respiratory modulation, with peak frequency in post-inspiration. Action potentials arose from unitary EPSPs and autocorrelation of those events showed that each ganglion cell received inputs from a single active preganglionic source. Peripheral chemoreceptor, arterial baroreceptor and diving response activation all evoked high frequency synaptic barrages in these cells, always from the same single preganglionic source. EPSP amplitudes showed frequency dependent depression, leading to more spike failures at shorter inter-event intervals. These findings indicate that rather than integrating convergent inputs, cardiac vagal postganglionic neurones gate preganglionic inputs, so regulating the proportion of central parasympathetic tone that is transmitted on to the heart.
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Affiliation(s)
- Robin M McAllen
- Florey Neuroscience Institutes and Department of Anatomy & Cell Biology, University of Melbourne, Melbourne, Victoria 3010, Australia
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29
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Abstract
The methods used to assess cardiac parasympathetic (cardiovagal) activity and its effects on the heart in both humans and animal models are reviewed. Heart rate (HR)-based methods include measurements of the HR response to blockade of muscarinic cholinergic receptors (parasympathetic tone), beat-to-beat HR variability (HRV) (parasympathetic modulation), rate of post-exercise HR recovery (parasympathetic reactivation), and reflex-mediated changes in HR evoked by activation or inhibition of sensory (afferent) nerves. Sources of excitatory afferent input that increase cardiovagal activity and decrease HR include baroreceptors, chemoreceptors, trigeminal receptors, and subsets of cardiopulmonary receptors with vagal afferents. Sources of inhibitory afferent input include pulmonary stretch receptors with vagal afferents and subsets of visceral and somatic receptors with spinal afferents. The different methods used to assess cardiovagal control of the heart engage different mechanisms, and therefore provide unique and complementary insights into underlying physiology and pathophysiology. In addition, techniques for direct recording of cardiovagal nerve activity in animals; the use of decerebrate and in vitro preparations that avoid confounding effects of anesthesia; cardiovagal control of cardiac conduction, contractility, and refractoriness; and noncholinergic mechanisms are described. Advantages and limitations of the various methods are addressed, and future directions are proposed.
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Affiliation(s)
- Mark W Chapleau
- The Cardiovascular Center and Department of Internal Medicine, The University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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30
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Mousa SA, Shaqura M, Schäper J, Huang W, Treskatsch S, Habazettl H, Abdul-Khaliq H, Schäfer M. Identification of mu- and kappa-opioid receptors as potential targets to regulate parasympathetic, sympathetic, and sensory neurons within rat intracardiac ganglia. J Comp Neurol 2010; 518:3836-47. [PMID: 20653037 DOI: 10.1002/cne.22427] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent interest has been focused on the opioid regulation of heart performance; however, specific allocation of opioid receptors to the parasympathetic, sympathetic, and sensory innervations of the heart is scarce. Therefore, the present study aimed to characterize such specific target sites for opioids in intracardiac ganglia, which act as a complex network for the integration of the heart's neuronal in- and output. Tissue samples from rat heart atria were subjected to RT-PCR, Western blot, radioligand-binding, and double immunofluorescence confocal analysis of mu (M)- and kappa (K)-opioid receptors (ORs) with the neuronal markers vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), and substance P (SP). Our results demonstrated MOR- and KOR-specific mRNA, receptor protein, and selective membrane ligand binding. By using immunofluorescence confocal microscopy, MOR and KOR immunoreactivity were colocalized with VAChT in large-diameter parasympathetic principal neurons, with TH-immunoreactive small intensely fluorescent (SIF) cells, and on nearby TH-IR varicose terminals. In addition, MOR and KOR immunoreactivity were identified on CGRP- and SP-IR sensory neurons throughout intracardiac ganglia and atrial myocardium. Our findings show that MOR and KOR are expressed as mRNA and translated into specific receptor proteins on cardiac parasympathetic, sympathetic, and sensory neurons as potential binding sites for opioids. Thus, they may well play a role within the complex network for the integration of the heart's neuronal in- and output.
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Affiliation(s)
- Shaaban A Mousa
- Department of Anesthesiology and Intensive Care Medicine, Charité University Berlin, Campus Virchow Klinikum and Campus Charite Mitte, 13353 Berlin, Germany.
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Dyavanapalli J, Rimmer K, Harper AA. Reactive oxygen species alters the electrophysiological properties and raises [Ca2+]i in intracardiac ganglion neurons. Am J Physiol Regul Integr Comp Physiol 2010; 299:R42-54. [PMID: 20445155 PMCID: PMC2917765 DOI: 10.1152/ajpregu.00053.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have investigated the effects of the reactive oxygen species (ROS) donors hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (t-BHP) on the intrinsic electrophysiological characteristics: ganglionic transmission and resting [Ca2+]i in neonate and adult rat intracardiac ganglion (ICG) neurons. Intracellular recordings were made using sharp microelectrodes filled with either 0.5 M KCl or Oregon Green 488 BAPTA-1, allowing recording of electrical properties and measurement of [Ca2+]i. H2O2 and t-BHP both hyperpolarized the resting membrane potential and reduced membrane resistance. In adult ICG neurons, the hyperpolarizing action of H2O2 was reversed fully by Ba2+ and partially by tetraethylammonium, muscarine, and linopirdine. H2O2 and t-BHP reduced the action potential afterhyperpolarization (AHP) amplitude but had no impact on either overshoot or AHP duration. ROS donors evoked an increase in discharge adaptation to long depolarizing current pulses. H2O2 blocked ganglionic transmission in most ICG neurons but did not alter nicotine-evoked depolarizations. By contrast, t-BHP had no significant action on ganglionic transmission. H2O2 and t-BHP increased resting intracellular Ca2+ levels to 1.6 ( ± 0.6, n = 11, P < 0.01) and 1.6 ( ± 0.3, n = 8, P < 0.001), respectively, of control value (1.0, ∼60 nM). The ROS scavenger catalase prevented the actions of H2O2, and this protection extended beyond the period of application. Superoxide dismutase partially shielded against the action of H2O2, but this was limited to the period of application. These data demonstrate that ROS decreases the excitability and ganglionic transmission of ICG neurons, attenuating parasympathetic control of the heart.
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Affiliation(s)
- Jhansi Dyavanapalli
- Division of Molecular Physiology, James Black Centre, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
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32
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Zimerman L, Liberman A, Castro R, Ribeiro J, Nóbrega A. Acute electrophysiologic consequences of pyridostigmine inhibition of cholinesterase in humans. Braz J Med Biol Res 2010; 43:211-6. [DOI: 10.1590/s0100-879x2010005000001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 11/04/2009] [Indexed: 03/25/2023] Open
Affiliation(s)
- L.I. Zimerman
- Hospital de Clínicas de Porto Alegre, Brasil; Universidade Federal do Rio Grande do Sul, Brasil
| | - A. Liberman
- Hospital de Clínicas de Porto Alegre, Brasil
| | | | - J.P. Ribeiro
- Hospital de Clínicas de Porto Alegre, Brasil; Universidade Federal do Rio Grande do Sul, Brasil
| | - A.C.L. Nóbrega
- Universidade Federal Fluminense; Universidade Federal Fluminense, Brasil
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33
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Lin M, Ai J, Li L, Huang C, Chapleau MW, Liu R, Gozal D, Wead WB, Wurster RD, Cheng Z'J'. Structural remodeling of nucleus ambiguus projections to cardiac ganglia following chronic intermittent hypoxia in C57BL/6J mice. J Comp Neurol 2008; 509:103-17. [PMID: 18425809 DOI: 10.1002/cne.21732] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The baroreflex control of heart rate (HR) is reduced following chronic intermittent hypoxia (CIH). Since the nucleus ambiguus (NA) plays a key role in baroreflex control of HR, we examined whether CIH remodels vagal efferent projections to cardiac ganglia. C57BL/6J mice (3-4 months of age) were exposed to either room air (RA) or CIH for 3 months. Confocal microscopy was used to examine NA axons and terminals in cardiac ganglia following Fluoro-Gold (FG) injections to label cardiac ganglia, and microinjections of tracer DiI into the left NA to anterogradely label vagal efferents. We found that: 1) Cardiac ganglia were widely distributed on the dorsal surface of the atria. Although the total number of cardiac ganglia did not differ between RA and CIH mice, the size of ganglia and the somatic area of cardiac principal neurons (PNs) were significantly decreased (P < 0.01), and the size of the PN nuclei was increased following CIH (P < 0.01). 2) NA axons entered cardiac ganglia and innervated PNs with dense basket endings in both RA and CIH mice, and the percentage of innervated PNs was similar (RA: 50 +/- 1.0%; CIH: 49 +/- 1.0%; P > 0.10). In CIH mice, however, swollen cardiac axons and terminals without close contacts to PNs were found. Furthermore, varicose endings around PNs appeared swollen and the axonal varicose area around PNs was almost doubled in size (CIH: 163.1 +/- 6.4 microm(2); RA: 88 +/- 3.9 microm(2), P < 0.01). Thus, CIH significantly altered the structure of cardiac ganglia and resulted in reorganized vagal efferent projections to cardiac ganglia. Such remodeling of cardiac ganglia and vagal efferent projections provides new insight into the effects of CIH on the brain-heart circuitry of C57BL/6J mice.
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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 32816, USA
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Dyavanapalli J, Rimmer K, Harper AA. The action of high K+ and aglycaemia on the electrical properties and synaptic transmission in rat intracardiac ganglion neurones in vitro. Exp Physiol 2008; 94:201-12. [PMID: 18978036 PMCID: PMC2713859 DOI: 10.1113/expphysiol.2008.044784] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have investigated the action of two elements of acute ischaemia, high potassium and aglycaemia, on the electrophysiological properties and ganglionic transmission of adult rat intracardiac ganglion (ICG) neurones. We used a whole-mount ganglion preparation of the right atrial ganglion plexus and sharp microelectrode recording techniques. Increasing extracellular K+ from its normal value of 4.7 mm to 10 mm decreased membrane potential and action potential after-hyperpolarization amplitude but otherwise had no effect on postganglionic membrane properties. It did, however, reduce the ability of synaptically evoked action potentials to follow high-frequency (100 Hz) repetitive stimulation. A further increase in K+ changed both the passive and the active membrane properties of the postganglionic neurone: time constant, membrane resistance and action potential overshoot were all decreased in high K+ (20 mm). The ICG neurones display a predominantly phasic discharge in response to prolonged depolarizing current pulses. High K+ had no impact on this behaviour but reduced the time-dependent rectification response to hyperpolarizing currents. At 20 mm, K+ practically blocked ganglionic transmission in most neurones at all frequencies tested. Aglycaemia, nominally glucose-free physiological saline solution (PSS), increased the time constant and membrane resistance of ICG neurones but otherwise had no action on their passive or active properties or ganglionic transmission. However, the combination of aglycaemia and 20 mm K+ displayed an improvement in passive properties and ganglionic transmission when compared with 20 mm K+ PSS. These data indicate that the presynaptic terminal is the primary target of high extracellular potassium and that aglycaemia may have protective actions against this challenge.
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Post-operative atrial fibrillation management by selective epicardial vagal fat pad stimulation. J Interv Card Electrophysiol 2008; 24:37-45. [PMID: 18758932 DOI: 10.1007/s10840-008-9286-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 05/29/2008] [Indexed: 12/21/2022]
Abstract
PURPOSE Post-operative atrial fibrillation (POAF) is a common complication after cardiac surgery and often leads to poorly tolerated fast ventricular rates. Negative dromotropic drugs are not always effective and may not be well tolerated in heart failure patients. Aim of this study is to verify if high-frequency stimulation of the right inferior fat pad (RIFPS) allows an effective decrease in ventricular rate (VR) during POAF. METHODS We enrolled 32 consecutive patients submitted to bypass; during surgery, a temporary heart wire was implanted in a site where RIFPS evoked a functional AV block. During POAF, RIFPS was delivered from the heart wire to decrease VR. RESULTS Intra-operative RIFPS evoked complete AV block in 29 patients (91%). Fourteen patients (44%) developed POAF (mean VR 127 +/- 12 bpm). In these patients, RIFPS achieved a 25% reduction of VR and complete AV block with 6.0 +/- 1.9 and 7.5 +/- 1.8 V (duration 0.2 ms, frequency 50 Hz), respectively. CONCLUSION Epicardial RIFPS represents an effective and feasible technique to decrease VR during POAF.
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36
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Morphology and topography of nucleus ambiguus projections to cardiac ganglia in rats and mice. Neuroscience 2007; 149:845-60. [PMID: 17942236 DOI: 10.1016/j.neuroscience.2007.07.062] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 06/30/2007] [Accepted: 08/18/2007] [Indexed: 12/13/2022]
Abstract
Vagal efferent axons from the nucleus ambiguus (NA) innervate ganglionated plexuses in the dorsal surface of cardiac atria, which in turn, may have different functional roles in cardiac regulation. However, the morphology and topography of vagal efferent projections to these ganglionated plexuses in rats and mice have not been well delineated. In the present study, we injected the tracer 1,1'-dioctadecyl-3,3,3',3' tetramethylindocarbocyanine methanesulfonate (DiI) into the left NA to label vagal efferent axons and terminals in cardiac ganglia and administered Fluoro-Gold (FG) i.p. to stain cardiac ganglia. Then, we used confocal microscopy and a Neurolucida 3-D Digitization System to qualitatively and quantitatively examine the distribution and structure of cardiac ganglia, and NA efferent projections to cardiac ganglia in the whole-mounts of Sprague-Dawley (SD) rats and FVB mice. Our observations were: 1) Cardiac ganglia of different shapes and sizes were distributed in the sinoatrial (SA) node, atrioventricular (AV) node, and lower pulmonary vein (LPV) regions on the dorsal surface of the atria. In each region, several ganglia formed a ganglionated plexus. The plexuses at different locations were interconnected by nerves. 2) Vagal efferent fibers ramified within cardiac ganglia, formed a complex network of axons, and innervated cardiac ganglia with very dense basket endings around individual cardiac principal neurons (PNs). 3) The percent of the PNs in cardiac ganglia which were innervated by DiI-labeled axons was 54.3+/-3.2% in mice vs. 53.2+/-3.2% in rats (P>0.10). 4) The density of axonal putative-synaptic varicosities on the surface of PNs was 0.15+/-0.02/microm(2) in mice vs. 0.16+/-0.02/microm(2) in rats (P>0.10). Thus, the distributions of cardiac ganglia and vagal efferent projections to cardiac ganglia in mice and rats were quite similar both qualitatively and quantitatively. Our study provides the structural foundation for future investigation of functional differentiation of ganglionated plexuses and the brain-heart circuitry in rodent models of human disease.
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Rimmer K, Harper AA. Developmental Changes in Electrophysiological Properties and Synaptic Transmission in Rat Intracardiac Ganglion Neurons. J Neurophysiol 2006; 95:3543-52. [PMID: 16611840 DOI: 10.1152/jn.01220.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We charted postnatal changes in the intrinsic electrophysiological properties and synaptic responses of rat intrinsic cardiac ganglion (ICG) neurons. We developed a whole-mount ganglion preparation of the excised right atrial ganglion plexus. Using intracellular recordings and nerve stimulation we tested the hypothesis that substantial transformations in the intrinsic electrical characteristics and synaptic transmission accompany postnatal development. Membrane potential ( Em) did not change but time constant (τ) and cell capacitance increased with postnatal development. Accordingly, input resistance ( Rin) decreased but specific membrane resistance ( Rm) increased postnatally. Comparison of the somatic active membrane properties revealed significant changes in electrical phenotype. All neonatal neurons had somatic action potentials (APs) with small overshoots and small afterhyperpolarizations (AHPs). Adult neurons had somatic APs with large overshoots and large AHP amplitudes. The range of AHP duration was larger in adults than in neonates. The AP characteristics of juvenile neurons resembled those of adults, with the exception of AHP duration, which fell midway between neonate and adult values. Phasic, multiply adapting, and tonic evoked discharge activities were recorded from ICG neurons. Most neurons displayed phasic discharge at each developmental stage. All neurons received excitatory synaptic inputs from the vagus or interganglionic nerve trunk(s), the strength of which did not change significantly with postnatal age. The changes in the electrophysiological properties of the postganglionic neuron suggest that increased complexity of parasympathetic regulation of cardiac function accompanies postnatal development.
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Affiliation(s)
- Katrina Rimmer
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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38
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Fischer H, Harper AA, Anderson CR, Adams DJ. Developmental changes in expression of GABAA receptor-channels in rat intrinsic cardiac ganglion neurones. J Physiol 2005; 564:465-74. [PMID: 15731187 PMCID: PMC1464452 DOI: 10.1113/jphysiol.2005.084012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The effects of gamma-aminobutyric acid (GABA) on the electrophysiological properties of intracardiac neurones were investigated in the intracardiac ganglion plexus in situ and in dissociated neurones from neonatal, juvenile and adult rat hearts. Focal application of GABA evoked a depolarizing, excitatory response in both intact and dissociated intracardiac ganglion neurones. Under voltage clamp, both GABA and muscimol elicited inward currents at -60 mV in a concentration-dependent manner. The fast, desensitizing currents were mimicked by the GABA(A) receptor agonists muscimol and taurine, and inhibited by the GABA(A) receptor antagonists, bicuculline and picrotoxin. The GABA(A0) antagonist (1,2,5,6-tetrahydropyridin-4-yl)methyl phosphonic acid (TPMPA), had no effect on GABA-induced currents, suggesting that GABA(A) receptor-channels mediate the response. The GABA-evoked current amplitude recorded from dissociated neurones was age dependent whereby the peak current density measured at -100 mV was approximately 20 times higher for intracardiac neurones obtained from neonatal rats (P2-5) compared with adult rats (P45-49). The decrease in GABA sensitivity occurred during the first two postnatal weeks and coincides with maturation of the sympathetic innervation of the rat heart. Immunohistochemical staining using antibodies against GABA demonstrate the presence of GABA in the intracardiac ganglion plexus of the neonatal rat heart. Taken together, these results suggest that GABA and taurine may act as modulators of neurotransmission and cardiac function in the developing mammalian intrinsic cardiac nervous system.
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Affiliation(s)
- Harald Fischer
- School of Biomedical Sciences, University of Queensland, Brisbane QLD 4072, Australia
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Sweeney C, Markos F. The role of neuronal nitric oxide in the vagal control of cardiac interval of the rat heart in vitro. Auton Neurosci 2004; 111:110-5. [PMID: 15182740 DOI: 10.1016/j.autneu.2004.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 04/16/2004] [Accepted: 04/17/2004] [Indexed: 11/17/2022]
Abstract
The aim of this study was to examine the role of neuronal nitric oxide (NO) on vagal regulation of the rat heart in vitro using the neuronal nitric oxide synthase (nNOS) inhibitor 1-(2-trifluoromethylphenyl) imidazole (TRIM). All experiments were carried out in the presence of the beta-adrenoreceptor antagonist atenolol (4 microM). Right thoracic vagus, or its cardiac branch, was stimulated at frequencies of 2, 4, 8, 16 and 32 Hz (pulse duration 1 ms, 20 V, for 20 s) before and after addition of TRIM (0.14 mM) and cardiac interval (ms) assessed. There was a significant positive linear correlation between cardiac interval and vagal frequency giving a slope of 2.76+/-0.8 ms/Hz (slope+/-S.E. slope; data pooled from eight rats) which was significantly attenuated following TRIM to 0.4+/-0.6 ms/Hz (P<0.05 ANOVA; n=8 rats). Nicotine applied in cumulative concentrations (0.03, 0.1, 0.3, 0.5, 1 mM) caused a linear concentration-dependent increase in cardiac interval, with a slope of 403+/-72 ms/mM (n=10 rats) which was significantly attenuated after treatment with hexamethonium (28 microM), to 190+/-36 ms/mM (n=10 rats, P<0.05 ANOVA), and atropine (3 microM) 100+/-31 ms/mM (n=9 rats, P<0.05 ANOVA) but not following TRIM (0.14 mM) 262+/-48 ms/mM (n=9 rats, P<0.05 ANOVA). These results suggest that NO facilitates vagal effects on the rat heart in vitro by an action at the pre-ganglionic/post-ganglionic synapse.
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Affiliation(s)
- Catherine Sweeney
- Department of Human Anatomy and Physiology, University College Dublin, Earlsfort Terrace, Dublin 2, Ireland
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