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Haberbusch M, Kronsteiner B, Kramer AM, Kiss A, Podesser BK, Moscato F. Closed-loop vagus nerve stimulation for heart rate control evaluated in the Langendorff-perfused rabbit heart. Sci Rep 2022; 12:18794. [PMID: 36335207 PMCID: PMC9637096 DOI: 10.1038/s41598-022-23407-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/31/2022] [Indexed: 11/07/2022] Open
Abstract
Persistent sinus tachycardia substantially increases the risk of cardiac death. Vagus nerve stimulation (VNS) is known to reduce the heart rate, and hence may be a non-pharmacological alternative for the management of persistent sinus tachycardia. To precisely regulate the heart rate using VNS, closed-loop control strategies are needed. Therefore, in this work, we developed two closed-loop VNS strategies using an in-silico model of the cardiovascular system. Both strategies employ a proportional-integral controller that operates on the current amplitude. While one control strategy continuously delivers stimulation pulses to the vagus nerve, the other applies bursts of stimuli in synchronization with the cardiac cycle. Both were evaluated in Langendorff-perfused rabbit hearts (n = 6) with intact vagal innervation. The controller performance was quantified by rise time (Tr), steady-state error (SSE), and percentual overshoot amplitude (%OS). In the ex-vivo setting, the cardiac-synchronized variant resulted in Tr = 10.7 ± 4.5 s, SSE = 12.7 ± 9.9 bpm and %OS = 5.1 ± 3.6% while continuous stimulation led to Tr = 10.2 ± 5.6 s, SSE = 10 ± 6.7 bpm and %OS = 3.2 ± 1.9%. Overall, both strategies produced a satisfying and reproducible performance, highlighting their potential use in persistent sinus tachycardia.
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Affiliation(s)
- Max Haberbusch
- grid.22937.3d0000 0000 9259 8492Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria ,grid.454395.aLudwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Bettina Kronsteiner
- grid.22937.3d0000 0000 9259 8492Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria ,grid.454395.aLudwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria ,grid.22937.3d0000 0000 9259 8492Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Anne-Margarethe Kramer
- grid.22937.3d0000 0000 9259 8492Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Attila Kiss
- grid.454395.aLudwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria ,grid.22937.3d0000 0000 9259 8492Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Bruno K. Podesser
- grid.454395.aLudwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria ,grid.22937.3d0000 0000 9259 8492Center for Biomedical Research, Medical University of Vienna, Vienna, Austria ,Ludwig Boltzmann Cluster for Tissue Regeneration, Vienna, Austria
| | - Francesco Moscato
- grid.22937.3d0000 0000 9259 8492Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria ,grid.454395.aLudwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria ,Ludwig Boltzmann Cluster for Tissue Regeneration, Vienna, Austria
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2
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Allen E, Pongpaopattanakul P, Chauhan RA, Brack KE, Ng GA. The Effects of Vagus Nerve Stimulation on Ventricular Electrophysiology and Nitric Oxide Release in the Rabbit Heart. Front Physiol 2022; 13:867705. [PMID: 35755432 PMCID: PMC9213784 DOI: 10.3389/fphys.2022.867705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 05/18/2022] [Indexed: 12/03/2022] Open
Abstract
Background: Abnormal autonomic activity including impaired parasympathetic control is a known hallmark of heart failure (HF). Vagus nerve stimulation (VNS) has been shown to reduce the susceptibility of the heart to ventricular fibrillation, however the precise underlying mechanisms are not well understood and the detailed stimulation parameters needed to improve patient outcomes clinically are currently inconclusive. Objective: To investigate NO release and cardiac electrophysiological effects of electrical stimulation of the vagus nerve at varying parameters using the isolated innervated rabbit heart preparation. Methods: The right cervical vagus nerve was electrically stimulated in the innervated isolated rabbit heart preparation (n = 30). Heart rate (HR), effective refractory period (ERP), ventricular fibrillation threshold (VFT) and electrical restitution were measured as well as NO release from the left ventricle. Results: High voltage with low frequency VNS resulted in the most significant reduction in HR (by −20.6 ± 3.3%, −25.7 ± 3.0% and −30.5 ± 3.0% at 0.1, 1 and 2 ms pulse widths, with minimal increase in NO release. Low voltage and high frequency VNS significantly altered NO release in the left ventricle, whilst significantly flattening the slope of restitution and significantly increasing VFT. HR changes however using low voltage, high frequency VNS were minimal at 20Hz (to 138.5 ± 7.7 bpm (−7.3 ± 2.0%) at 1 ms pulse width and 141.1 ± 6.6 bpm (−4.4 ± 1.1%) at 2 ms pulse width). Conclusion: The protective effects of the VNS are independent of HR reductions demonstrating the likelihood of such effects being as a result of the modulation of more than one molecular pathway. Altering the parameters of VNS impacts neural fibre recruitment in the ventricle; influencing changes in ventricular electrophysiology, the protective effect of VNS against VF and the release of NO from the left ventricle.
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Affiliation(s)
- Emily Allen
- Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.,NIHR Leicester BRC, Glenfield Hospital, Leicester, United Kingdom
| | - Pott Pongpaopattanakul
- Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.,NIHR Leicester BRC, Glenfield Hospital, Leicester, United Kingdom
| | - Reshma A Chauhan
- Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.,NIHR Leicester BRC, Glenfield Hospital, Leicester, United Kingdom
| | - Kieran E Brack
- Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.,NIHR Leicester BRC, Glenfield Hospital, Leicester, United Kingdom
| | - G André Ng
- Department of Cardiovascular Sciences, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.,NIHR Leicester BRC, Glenfield Hospital, Leicester, United Kingdom
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3
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Jungen C, Scherschel K, Flenner F, Jee H, Rajendran P, De Jong KA, Nikolaev V, Meyer C, Ardell JL, Tompkins JD. Increased arrhythmia susceptibility in type 2 diabetic mice related to dysregulation of ventricular sympathetic innervation. Am J Physiol Heart Circ Physiol 2019; 317:H1328-H1341. [PMID: 31625779 DOI: 10.1152/ajpheart.00249.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Patients with type 2 diabetes mellitus (T2DM) have a greater risk of developing life-threatening cardiac arrhythmias. Because the underlying mechanisms and potential influence of diabetic autonomic neuropathy are not well understood, we aimed to assess the relevance of a dysregulation in cardiac autonomic tone. Ventricular arrhythmia susceptibility was increased in Langendorff-perfused hearts isolated from mice with T2DM (db/db). Membrane properties and synaptic transmission were similar at cardiac postganglionic parasympathetic neurons from diabetic and control mice; however, a greater asynchronous neurotransmitter release was present at sympathetic postganglionic neurons from the stellate ganglia of db/db mice. Western blot analysis showed a reduction of tyrosine hydroxylase (TH) from the ventricles of db/db mice, which was confirmed with confocal imaging as a heterogeneous loss of TH-immunoreactivity from the left ventricular wall but not the apex. In vivo stimulation of cardiac parasympathetic (vagus) or cardiac sympathetic (stellate ganglion) nerves induced similar changes in heart rate in control and db/db mice, and the kinetics of pacing-induced Ca2+ transients (recorded from isolated cardiomyocytes) were similar in control and db/db cells. Antagonism of cardiac muscarinic receptors did not affect the frequency or severity of arrhythmias in db/db mice, but sympathetic blockade with propranolol completely inhibited arrhythmogenicity. Collectively, these findings suggest that the increased ventricular arrhythmia susceptibility of type 2 diabetic mouse hearts is due to dysregulation of the sympathetic ventricular control.NEW & NOTEWORTHY Patients with type 2 diabetes mellitus have greater risk of suffering from sudden cardiac death. We found that the increased ventricular arrhythmia susceptibility in type 2 diabetic mouse hearts is due to cardiac sympathetic dysfunction. Sympathetic dysregulation is indicated by an increased asynchronous release at stellate ganglia, a heterogeneous loss of tyrosine hydroxylase from the ventricular wall but not apex, and inhibition of ventricular arrhythmias in db/db mice after β-sympathetic blockade.
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Affiliation(s)
- Christiane Jungen
- Department of Cardiology-Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Katharina Scherschel
- Department of Cardiology-Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Frederik Flenner
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany.,Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Centre, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Haesung Jee
- University of California, Los Angeles Cardiac Arrhythmia Center, Neurocardiology Research Program of Excellence, Department of Medicine-Cardiology, Los Angeles, California
| | - Pradeep Rajendran
- University of California, Los Angeles Cardiac Arrhythmia Center, Neurocardiology Research Program of Excellence, Department of Medicine-Cardiology, Los Angeles, California
| | - Kirstie A De Jong
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany.,Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, University of Hamburg, Germany
| | - Viacheslav Nikolaev
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany.,Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, University of Hamburg, Germany
| | - Christian Meyer
- Department of Cardiology-Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Jeffrey L Ardell
- University of California, Los Angeles Cardiac Arrhythmia Center, Neurocardiology Research Program of Excellence, Department of Medicine-Cardiology, Los Angeles, California
| | - John D Tompkins
- University of California, Los Angeles Cardiac Arrhythmia Center, Neurocardiology Research Program of Excellence, Department of Medicine-Cardiology, Los Angeles, California
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4
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Yeo JM, Tse V, Kung J, Lin HY, Lee YT, Kwan J, Yan BP, Tse G. Isolated heart models for studying cardiac electrophysiology: a historical perspective and recent advances. J Basic Clin Physiol Pharmacol 2018; 28:191-200. [PMID: 28063261 DOI: 10.1515/jbcpp-2016-0110] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/12/2016] [Indexed: 01/25/2023]
Abstract
Experimental models used in cardiovascular research range from cellular to whole heart preparations. Isolated whole hearts show higher levels of structural and functional integration than lower level models such as tissues or cellular fragments. Cardiovascular diseases are multi-factorial problems that are dependent on highly organized structures rather than on molecular or cellular components alone. This article first provides a general introduction on the animal models of cardiovascular diseases. It is followed by a detailed overview and a historical perspective of the different isolated heart systems with a particular focus on the Langendorff perfusion method for the study of cardiac arrhythmias. The choice of species, perfusion method, and perfusate composition are discussed in further detail with particular considerations of the theoretical and practical aspects of experimental settings.
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Affiliation(s)
- Jie Ming Yeo
- School of Medicine, Imperial College London, London
| | - Vivian Tse
- Department of Physiology, McGill University, Montreal, Quebec
| | - Judy Kung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Hiu Yu Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Yee Ting Lee
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Joseph Kwan
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Bryan P Yan
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne
| | - Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R
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5
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Jungen C, Scherschel K, Eickholt C, Kuklik P, Klatt N, Bork N, Salzbrunn T, Alken F, Angendohr S, Klene C, Mester J, Klöcker N, Veldkamp MW, Schumacher U, Willems S, Nikolaev VO, Meyer C. Disruption of cardiac cholinergic neurons enhances susceptibility to ventricular arrhythmias. Nat Commun 2017; 8:14155. [PMID: 28128201 PMCID: PMC5290156 DOI: 10.1038/ncomms14155] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 11/28/2016] [Indexed: 12/19/2022] Open
Abstract
The parasympathetic nervous system plays an important role in the pathophysiology of atrial fibrillation. Catheter ablation, a minimally invasive procedure deactivating abnormal firing cardiac tissue, is increasingly becoming the therapy of choice for atrial fibrillation. This is inevitably associated with the obliteration of cardiac cholinergic neurons. However, the impact on ventricular electrophysiology is unclear. Here we show that cardiac cholinergic neurons modulate ventricular electrophysiology. Mechanical disruption or pharmacological blockade of parasympathetic innervation shortens ventricular refractory periods, increases the incidence of ventricular arrhythmia and decreases ventricular cAMP levels in murine hearts. Immunohistochemistry confirmed ventricular cholinergic innervation, revealing parasympathetic fibres running from the atria to the ventricles parallel to sympathetic fibres. In humans, catheter ablation of atrial fibrillation, which is accompanied by accidental parasympathetic and concomitant sympathetic denervation, raises the burden of premature ventricular complexes. In summary, our results demonstrate an influence of cardiac cholinergic neurons on the regulation of ventricular function and arrhythmogenesis. Catheter ablation is a common therapy for atrial fibrillation but disrupts cardiac cholinergic neurons. Here the authors report that cholinergic neurons innervate heart ventricles and show that their ablation leads to increased susceptibility to ventricular arrhythmias in mouse models and in patients.
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Affiliation(s)
- Christiane Jungen
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany
| | - Katharina Scherschel
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany
| | - Christian Eickholt
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Pawel Kuklik
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Niklas Klatt
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany
| | - Nadja Bork
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany.,Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Tim Salzbrunn
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Fares Alken
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Stephan Angendohr
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Christiane Klene
- Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Janos Mester
- Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Marieke W Veldkamp
- Academic Medical Center, University of Amsterdam, Department of Clinical and Experimental Cardiology, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Udo Schumacher
- Institute of Anatomy and Experimental Morphology, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Stephan Willems
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany
| | - Viacheslav O Nikolaev
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany.,Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Christian Meyer
- Department of Cardiology-Electrophysiology, cardiac Neuro- and Electrophysiology Research Group (cNEP), University Heart Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 13347 Berlin, Germany
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6
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Winter J, Cook AR, Patient DH, Emmett SR, Tattersall J, Shattock MJ. Reversal of cardiac vagal effects of physostigmine by adjunctive muscarinic blockade. Neurotoxicology 2016; 57:174-182. [PMID: 27693445 DOI: 10.1016/j.neuro.2016.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/31/2016] [Accepted: 09/28/2016] [Indexed: 11/18/2022]
Abstract
Pre-treatment with reversible acetylcholinesterase (AChE) inhibitors is an effective strategy for reducing lethality following organophosphate nerve agent exposure. AChE inhibition may have unwanted cardiac side effects, which could be negated by adjunctive anti-cholinergic therapy. The aims of the present study were to examine the concentration-dependent effects of physostigmine on cardiac responses to vagus nerve stimulation (VNS), to test whether adjunctive treatment with hyoscine can reverse these effects and to assess the functional interaction and electrophysiological consequences of a combined pre-treatment. Studies were performed in an isolated innervated rabbit heart preparation. The reduction in heart rate with VNS was augmented by physostigmine (1-1000nmol/L), in a concentration-dependent manner - with an EC50 of 19nmol/L. Hyoscine was shown to be effective at blocking the cardiac responses to VNS with an IC50 of 11nmol/L. With concomitant perfusion of physostigmine, the concentration-response curve for hyoscine was shifted downward and to the right, increasing the concentration of hyoscine required to normalise (to control values) the effects of physostigmine on heart rate. At the lowest concentration of hyoscine examined (1nmol/L) a modest potentiation of heart rate response to VNS (+15±3%) was observed. We found no evidence of cardiac dysfunction or severe electrophysiological abnormalities with either physostigmine or hyoscine alone, or as a combined drug-therapy. The main finding of this study is that hyoscine, at concentrations greater than 10-8M, is effective at reversing the functional effects of physostigmine on the heart. However, low-concentrations of hyoscine may augment cardiac parasympathetic control.
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Affiliation(s)
- James Winter
- Cardiovascular Division, King's College London, UK.
| | - Alexandra R Cook
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, UK
| | - Dawn H Patient
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, UK
| | - Stevan R Emmett
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, UK
| | - John Tattersall
- Defence Science and Technology Laboratory, Porton Down, Wiltshire, UK
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7
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Zosky GR, O'Shea JE. Cardiac autonomic innervation of the western pygmy possum (Cercatetus concinnus) and golden bandicoot (Isoodon auratus). J Comp Physiol B 2016; 187:203-211. [PMID: 27439719 DOI: 10.1007/s00360-016-1021-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/29/2016] [Accepted: 07/13/2016] [Indexed: 11/25/2022]
Abstract
Evidence for a functional ventricular parasympathetic innervation of the mammalian heart between and within taxa remains controversial. We have previously proposed that the presence of a functional parasympathetic innervation of the ventricle was indicative of heterothermy, and is essential for maintaining ventricular stability at low body temperature. However, it is possible that the presence of such an innervation is also representative of the primitive mammalian state. In this study, we aimed to determine whether a functional parasympathetic innervation of the ventricle, that is capable of actively reducing the force of contraction, is present across metatherian mammals. Using in vitro isolated cardiac preparations, we examined evidence for a functional ventricular parasympathetic innervation of the ventricle in two species of metatherian mammal, one heterotherm (Western pygmy possum; Cercatetus concinnus) and one homeotherm (Golden bandicoot; Isoodon auratus), from different families to complement existing data from a heterothermic dasyurid. Both C. concinnus and I. auratus had a potent biphasic response to transmural electrical stimulation in both atrial and ventricular preparations. Both the decrease and increase in the force of contraction in response to stimulation were almost entirely blocked by the cholinergic and adrenergic antagonists, atropine and propranolol, respectively. These observations provide clear evidence for a parasympathetic innervation of the ventricle that is capable of directly influencing the force of contraction across metatherian mammals with different thermoregulatory strategies. While this innervation may facilitate heterothermy, this suggests that the presence of such an innervation pattern is indicative of the primitive mammalian state.
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Affiliation(s)
- Graeme R Zosky
- Faculty of Health, School of Medicine, University of Tasmania, Private Bag 34, Hobart, TAS, 7000, Australia.
| | - James E O'Shea
- Faculty of Science, School of Animal Biology, The University of Western Australia, Crawley, WA, 6008, Australia
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8
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Huang WA, Shivkumar K, Vaseghi M. Device-based autonomic modulation in arrhythmia patients: the role of vagal nerve stimulation. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2015; 17:379. [PMID: 25894588 DOI: 10.1007/s11936-015-0379-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OPINION STATEMENT Vagal nerve stimulation (VNS) has shown promise as an adjunctive therapy for management of cardiac arrhythmias by targeting the cardiac parasympathetic nervous system. VNS has been evaluated in the setting of ischemia-driven ventricular arrhythmias and atrial arrhythmias, as well as a treatment option for heart failure. As better understanding of the complexities of the cardiac autonomic nervous system is obtained, vagal nerve stimulation will likely become a powerful tool in the current cardiovascular therapeutic armamentarium.
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Affiliation(s)
- William A Huang
- UCLA Cardiac Arrhythmia Center, University of California, 100 Medical Plaza, Suite 660, Los Angeles, CA, 90095, USA
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9
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Yamakawa K, So EL, Rajendran PS, Hoang JD, Makkar N, Mahajan A, Shivkumar K, Vaseghi M. Electrophysiological effects of right and left vagal nerve stimulation on the ventricular myocardium. Am J Physiol Heart Circ Physiol 2014; 307:H722-31. [PMID: 25015962 DOI: 10.1152/ajpheart.00279.2014] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vagal nerve stimulation (VNS) has been proposed as a cardioprotective intervention. However, regional ventricular electrophysiological effects of VNS are not well characterized. The purpose of this study was to evaluate effects of right and left VNS on electrophysiological properties of the ventricles and hemodynamic parameters. In Yorkshire pigs, a 56-electrode sock was used for epicardial (n = 12) activation recovery interval (ARI) recordings and a 64-electrode catheter for endocardial (n = 9) ARI recordings at baseline and during VNS. Hemodynamic recordings were obtained using a conductance catheter. Right and left VNS decreased heart rate (84 ± 5 to 71 ± 5 beats/min and 84 ± 4 to 73 ± 5 beats/min), left ventricular pressure (89 ± 9 to 77 ± 9 mmHg and 91 ± 9 to 83 ± 9 mmHg), and dP/dtmax (1,660 ± 154 to 1,490 ± 160 mmHg/s and 1,595 ± 155 to 1,416 ± 134 mmHg/s) and prolonged ARI (327 ± 18 to 350 ± 23 ms and 327 ± 16 to 347 ± 21 ms, P < 0.05 vs. baseline for all parameters and P = not significant for right VNS vs. left VNS). No anterior-posterior-lateral regional differences in the prolongation of ARI during right or left VNS were found. However, endocardial ARI prolonged more than epicardial ARI, and apical ARI prolonged more than basal ARI during both right and left VNS. Changes in dP/dtmax showed the strongest correlation with ventricular ARI effects (R(2) = 0.81, P < 0.0001) than either heart rate (R(2) = 0.58, P < 0.01) or left ventricular pressure (R(2) = 0.52, P < 0.05). Therefore, right and left VNS have similar effects on ventricular ARI, in contrast to sympathetic stimulation, which shows regional differences. The decrease in inotropy correlates best with ventricular electrophysiological effects.
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Affiliation(s)
- Kentaro Yamakawa
- Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Eileen L So
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California
| | - Pradeep S Rajendran
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Program, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Jonathan D Hoang
- Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Nupur Makkar
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California
| | - Aman Mahajan
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Program, David Geffen School of Medicine at UCLA, Los Angeles, California; and Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Kalyanam Shivkumar
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Program, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Marmar Vaseghi
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Program, David Geffen School of Medicine at UCLA, Los Angeles, California; and
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10
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LUO HAIJIAN, SI JUNQIANG, ZHANG FENGJIE, YANG ZHENYU, WANG RUXING. Cardiac inotropic rebound effect after washout of acetylcholine is associated with electrophysiological heterogeneity in Langendorff-perfused rabbit heart. Exp Ther Med 2014; 7:755-757. [PMID: 24520282 PMCID: PMC3919906 DOI: 10.3892/etm.2014.1486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 01/09/2014] [Indexed: 11/15/2022] Open
Abstract
Cardiac electrophysiological heterogeneity related to the washout of acetylcholine (ACh) remains incompletely characterized. The aim of this study was to examine whether positive cardiac inotropic action is associated with electrophysiological heterogeneity between the atrium and the ventricle after ACh perfusion and washout. Epicardial monophasic action potentials (MAPs) from the right ventricle and right atrium, as well as cardiac contractility, were recorded from isolated Langendorff-perfused rabbit hearts using MAP electrodes and a force transducer. The results indicated that rebound positive inotropic actions were induced by ACh washout with adrenaline preconditioning. This effect was accompanied by an increase in MAP amplitude (MAPA) in the right ventricle but not the right atrium. These findings indicate that cholinergic muscarinic stimulation may lead to positive cardiac inotropic action followed by changes in regional electrophysiological heterogeneity between the atrial and ventricular myocardium. Therefore, we hypothesize that electrophysiological heterogeneity is an underlying cause of arrhythmogenesis as well as hemodynamic disturbance elicited by sudden termination of vagus stimulation.
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Saburkina I, Gukauskiene L, Rysevaite K, Brack KE, Pauza AG, Pauziene N, Pauza DH. Morphological pattern of intrinsic nerve plexus distributed on the rabbit heart and interatrial septum. J Anat 2014; 224:583-93. [PMID: 24527844 DOI: 10.1111/joa.12166] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2014] [Indexed: 12/14/2022] Open
Abstract
Although the rabbit is routinely used as the animal model of choice to investigate cardiac electrophysiology, the neuroanatomy of the rabbit heart is not well documented. The aim of this study was to examine the topography of the intrinsic nerve plexus located on the rabbit heart surface and interatrial septum stained histochemically for acetylcholinesterase using pressure-distended whole hearts and whole-mount preparations from 33 Californian rabbits. Mediastinal cardiac nerves entered the venous part of the heart along the root of the right cranial vein (superior caval vein) and at the bifurcation of the pulmonary trunk. The accessing nerves of the venous part of the heart passed into the nerve plexus of heart hilum at the heart base. Nerves approaching the heart extended epicardially and innervated the atria, interatrial septum and ventricles by five nerve subplexuses, i.e. left and middle dorsal, dorsal right atrial, ventral right and left atrial subplexuses. Numerous nerves accessed the arterial part of the arterial part of the heart hilum between the aorta and pulmonary trunk, and distributed onto ventricles by the left and right coronary subplexuses. Clusters of intrinsic cardiac neurons were concentrated at the heart base at the roots of pulmonary veins with some positioned on the infundibulum. The mean number of intrinsic neurons in the rabbit heart is not significantly affected by aging: 2200 ± 262 (range 1517-2788; aged) vs. 2118 ± 108 (range 1513-2822; juvenile). In conclusion, despite anatomic differences in the distribution of intrinsic cardiac neurons and the presence of well-developed nerve plexus within the heart hilum, the topography of all seven subplexuses of the intrinsic nerve plexus in rabbit heart corresponds rather well to other mammalian species, including humans.
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Affiliation(s)
- Inga Saburkina
- Institute of Anatomy, Faculty of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania
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12
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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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Effects of percutaneous stimulation of both sympathetic and parasympathetic cardiac autonomic nerves on cardiac function in dogs. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2013; 7:282-9. [PMID: 23123996 DOI: 10.1097/imi.0b013e31826f14ff] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Augmentation of left ventricular (LV) contractility and heart rate (HR) by sympathetic nerve stimulation and amelioration of heart failure by vagal nerve stimulation has been reported. However, the effects of concomitant electrical stimulation of both sympathetic and parasympathetic cardiac nerves in tissues such as those of the cardiac plexus remain unclear. This study sought to assess acute changes in cardiac function and hemodynamics in response to endovascular cardiac plexus stimulation (CPS). METHODS Twelve dogs received endovascular CPS via a bipolar catheter within the right pulmonary artery. Stimulation frequency (20 Hz) and pulse width (4 milliseconds) were fixed; voltage varied (range, 15-60 V). RESULTS Results fell into three categories: 1, no response (n = 4); 2, an increase in systemic arterial pressure that was dependent on electrode placement (n = 4); and 3, a very reproducible and stable increase in aortic pressure (n = 4). In the third group, mean systolic aortic pressures, maximum value of the first derivative of LV pressure, and LV stroke work increased with stimulation (P < 0.02 for all parameters) as did cardiac output, end-systolic elastance, and preload recruitable stroke work (P = 0.03). Systemic and pulmonary vascular resistance, central venous pressure, pulmonary arterial pressure, and HR remained unchanged (P > 0.05). CONCLUSIONS In contrast to conventional inotropic agents, endovascular CPS induced significant and selective increases in LV contractility without increasing HR. Efforts to optimize electrode placement and fixation will improve the reproducibility of endovascular CPS treatment.
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Kobayashi M, Massiello A, Karimov JH, Van Wagoner DR, Fukamachi K. Cardiac autonomic nerve stimulation in the treatment of heart failure. Ann Thorac Surg 2013; 96:339-45. [PMID: 23747176 DOI: 10.1016/j.athoracsur.2012.12.060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 12/14/2012] [Accepted: 12/21/2012] [Indexed: 01/01/2023]
Abstract
Research on the therapeutic modulation of cardiac autonomic tone by electrical stimulation has yielded encouraging early clinical results. Vagus nerve stimulation has reduced the rates of morbidity and sudden death from heart failure, but therapeutic vagus nerve stimulation is limited by side effects of hypotension and bradycardia. Sympathetic nerve stimulation that has been implemented in the experiment may exacerbate the sympathetic-dominated autonomic imbalance. In contrast, concurrent stimulation of both sympathetic and parasympathetic cardiac nerves increases myocardial contractility without increasing heart rate. This review assesses the current state of electrical stimulation of the cardiac autonomic nervous system to treat heart failure.
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Affiliation(s)
- Mariko Kobayashi
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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15
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Kobayashi M, Sakurai S, Takaseya T, Shiose A, Kim HI, Fujiki M, Karimov JH, Dessoffy R, Massiello A, Borowski AG, Van Wagoner DR, Jung E, Fukamachi K. Effects of Percutaneous Stimulation of Both Sympathetic and Parasympathetic Cardiac Autonomic Nerves on Cardiac Function in Dogs. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2012. [DOI: 10.1177/155698451200700409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | | | - Tohru Takaseya
- Departments of Biomedical Engineering, Cleveland, OH USA
| | - Akira Shiose
- Departments of Biomedical Engineering, Cleveland, OH USA
| | - Hyun-Il Kim
- Departments of Biomedical Engineering, Cleveland, OH USA
| | - Masako Fujiki
- Departments of Biomedical Engineering, Cleveland, OH USA
| | | | | | - Alex Massiello
- Departments of Biomedical Engineering, Cleveland, OH USA
| | - Allen G. Borowski
- Cardiovascular Medicine, Miller Family Heart & Vascular Institute, Cleveland Clinic, Cleveland, OH USA
| | | | - Eugene Jung
- Global Cardiovascular Innovation Center, Cleveland, OH USA
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Winter J, Tanko AS, Brack KE, Coote JH, Ng GA. Differential cardiac responses to unilateral sympathetic nerve stimulation in the isolated innervated rabbit heart. Auton Neurosci 2012; 166:4-14. [DOI: 10.1016/j.autneu.2011.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 08/08/2011] [Accepted: 08/09/2011] [Indexed: 11/30/2022]
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17
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Brack KE, Coote JH, Ng GA. Quantitative analysis of the parasympathetic innervation of the porcine heart. Heart Rhythm 2010; 7:e2-3; author reply e3. [PMID: 20621614 DOI: 10.1016/j.hrthm.2010.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Indexed: 11/16/2022]
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18
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Bondke H, Borges AC, Petersen S, Walde T, Baumann G. Non-invasive assessment of myocardial contractility from force-frequency relationship in patients with implanted pacemakers: first results. Europace 2010; 12:968-71. [DOI: 10.1093/europace/euq096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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19
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Brack KE, Coote JH, Ng GA. Vagus nerve stimulation inhibits the increase in Ca2+ transient and left ventricular force caused by sympathetic nerve stimulation but has no direct effects alone--epicardial Ca2+ fluorescence studies using fura-2 AM in the isolated innervated beating rabbit heart. Exp Physiol 2009; 95:80-92. [PMID: 19700520 DOI: 10.1113/expphysiol.2009.048215] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The effects of direct autonomic nerve stimulation on the heart may be quite different to those of perfusion with pharmacological neuromodulating agents. This study was designed to investigate the effect of autonomic nerve stimulation on intracellular calcium fluorescence using fura-2 AM in the isolated Langendorff-perfused rabbit heart preparation with intact dual autonomic innervation. The effects of autonomic nerve stimulation on cardiac force and calcium transients were more obvious during intrinsic sinus rhythm. High-frequency (15 Hz, n = 5) right vagus nerve stimulation (VS) decreased heart rate from 142.7 +/- 2.6 to 75.5 +/- 10.2 beats min(-1) and left ventricular pressure from 36.4 +/- 3.2 to 25.9 +/- 1.9 mmHg, whilst simultaneously decreasing the diastolic and systolic level of the calcium transient. Direct sympathetic nerve stimulation (7 Hz, n = 8) increased heart rate (from 144.7 +/- 10.5 to 213.2 +/- 4.9 beats min(-1)) and left ventricular pressure (from 37.5 +/- 3.6 to 43.7 +/- 2.8 mmHg), whilst simultaneously increasing the diastolic and systolic level of the calcium transient. During constant ventricular pacing, the high-frequency right vagus nerve stimulation did not have any direct effect on ventricular force or the calcium transient (n = 8), but was effective in reducing the effect of direct sympathetic nerve stimulation.
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Affiliation(s)
- Kieran E Brack
- Cardiology Group, Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Groby Road, Leicester LE39QP, UK.
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Brack KE, Patel VH, Mantravardi R, Coote JH, Ng GA. Direct evidence of nitric oxide release from neuronal nitric oxide synthase activation in the left ventricle as a result of cervical vagus nerve stimulation. J Physiol 2009; 587:3045-54. [PMID: 19403619 DOI: 10.1113/jphysiol.2009.169417] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Information regarding vagal innervation in the cardiac ventricle is limited and the direct effect of vagal stimulation on ventricular myocardial function is controversial. We have recently provided indirect evidence that the anti-fibrillatory effect of vagus nerve stimulation on the ventricle is mediated by nitric oxide (NO). The aim of this study was to provide direct evidence for the release of nitric oxide in the cardiac ventricle during stimulation of the efferent parasympathetic fibres of the cervical vagus nerve. The isolated innervated rabbit heart was employed with the use of the NO fluorescent indicator 4,5-diaminofluorescein diacetate (DAF-2 DA) during stimulation of the cervical vagus nerves and acetylcholine perfusion in the absence and presence of the non-specific NO synthase inhibitor NG-nito-L-arginine (L-NNA) and the neuronal NO synthase selective inhibitor 1-(2-trifluormethylphenyl)imidazole (TRIM). Using the novel fluorescence method in the beating heart, we have shown that NO-dependent fluorescence is increased by 0.92 +/- 0.26, 1.20 +/- 0.30 and 1.91 +/- 0.27% (during low, medium and high frequency, respectively) in the ventricle in a stimulation frequency-dependent manner during vagus nerve stimulation, with comparable increases seen during separate stimulation of the left and right cervical vagus nerves. Background fluorescence is reduced during perfusion with L-NNA and the increase in fluorescence during high frequency vagal stimulation is inhibited during perfusion with both L-NNA (1.97 +/- 0.35% increase before L-NNA, 0.00 +/- 0.02% during L-NNA) and TRIM (1.78 +/- 0.18% increase before TRIM, -0.11 +/- 0.08% during TRIM). Perfusion with 0.1 microM acetylcholine increased NO fluorescence by 0.76 +/- 0.09% which was blocked by L-NNA (change of 0.00 +/- 0.03%) but not TRIM (increase of 0.82 +/- 0.21%). Activation of cardiac parasympathetic efferent nerve fibres by stimulation of the cervical vagus is associated with NO production and release in the ventricle of the rabbit, via the neuronal isoform of nitric oxide synthase.
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Affiliation(s)
- Kieran E Brack
- Cardiology Group, Department of Cardiovascular Sciences, University of Leicester, UK
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Abstract
1. The idea is introduced that cardiac rate, contractility or atrioventricular (A-V) conduction spread may be controlled independently by the brain. Limited data from reflex studies are cited to support this view. 2. Evidence is presented that individual autonomic post- and preganglionic neurons have quite specific actions on the heart. Premotor and other central neurons can have preferential actions on heart rate, contractility or A-V conduction. 3. The functional implications of selective cardiac control are discussed.
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Affiliation(s)
- Lauren M Salo
- Howard Florey Institute and Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia
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