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Olejnickova V, Kolesova H, Bartos M, Sedmera D, Gregorovicova M. The Tale-Tell Heart: Evolutionary tetrapod shift from aquatic to terrestrial life-style reflected in heart changes in axolotl (Ambystoma mexicanum). Dev Dyn 2021; 251:1004-1014. [PMID: 34423892 DOI: 10.1002/dvdy.413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 08/02/2021] [Accepted: 08/18/2021] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND During amphibian metamorphosis, the crucial moment lies in the rearrangement of the heart, reflecting the changes in circulatory demands. However, little is known about the exact shifts linked with this rearrangement. Here, we demonstrate such myocardial changes in axolotl (Ambystoma mexicanum) from the morphological and physiological point of view. RESULTS Micro-CT and histological analysis showed changes in ventricular trabeculae organization, completion of the atrial septum and its connection to the atrioventricular valve. Based on Myosin Heavy Chain and Smooth Muscle Actin expression we distinguished metamorphosis-induced changes in myocardial differentiation at the ventricular trabeculae and atrioventricular canal. Using optical mapping, faster speed of conduction through the atrioventricular canal was demonstrated in metamorphic animals. No differences between the groups were observed in the heart rates, ventricular activation times, and activation patterns. CONCLUSIONS Transition from aquatic to terrestrial life-style is reflected in the heart morphology and function. Rebuilding of the axolotl heart during metamorphosis was connected with reorganization of ventricular trabeculae, completion of the atrial septum and its connection to the atrioventricular valve, and acceleration of AV conduction.
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Affiliation(s)
- Veronika Olejnickova
- First Faculty of Medicine, Institute of Anatomy, Charles University, Prague, Czech Republic.,Department of Developmental Cardiology, Czech Academy of Sciences, Institute of Physiology, Prague, Czech Republic
| | - Hana Kolesova
- First Faculty of Medicine, Institute of Anatomy, Charles University, Prague, Czech Republic.,Department of Developmental Cardiology, Czech Academy of Sciences, Institute of Physiology, Prague, Czech Republic
| | - Martin Bartos
- First Faculty of Medicine, Institute of Anatomy, Charles University, Prague, Czech Republic.,First Faculty of Medicine, Institute of Dental Medicine, Charles University, Prague, Czech Republic
| | - David Sedmera
- First Faculty of Medicine, Institute of Anatomy, Charles University, Prague, Czech Republic.,Department of Developmental Cardiology, Czech Academy of Sciences, Institute of Physiology, Prague, Czech Republic
| | - Martina Gregorovicova
- First Faculty of Medicine, Institute of Anatomy, Charles University, Prague, Czech Republic.,Department of Developmental Cardiology, Czech Academy of Sciences, Institute of Physiology, Prague, Czech Republic
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Oláh A, Barta BA, Sayour AA, Ruppert M, Virág-Tulassay E, Novák J, Varga ZV, Ferdinandy P, Merkely B, Radovits T. Balanced Intense Exercise Training Induces Atrial Oxidative Stress Counterbalanced by the Antioxidant System and Atrial Hypertrophy That Is Not Associated with Pathological Remodeling or Arrhythmogenicity. Antioxidants (Basel) 2021; 10:antiox10030452. [PMID: 33803975 PMCID: PMC7999710 DOI: 10.3390/antiox10030452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 12/16/2022] Open
Abstract
Although regular exercise training is associated with cardiovascular benefits, the increased risk of atrial arrhythmias has been observed after vigorous exercise and has been related to oxidative stress. We aimed at investigating exercise-induced atrial remodeling in a rat model of an athlete’s heart and determining sex-specific differences. Age-matched young adult rats were divided into female exercised, female control, male exercised, and male control groups. After exercised animals completed a 12-week-long swim training protocol, echocardiography and in vivo cardiac electrophysiologic investigation were performed. Additionally, atrial histological and gene expression analyses were carried out. Post-mortem atrial weight data and histological examination confirmed marked atrial hypertrophy. We found increased atrial gene expression of antioxidant enzymes along with increased nitro-oxidative stress. No gene expression alteration was found regarding markers of pathological remodeling, apoptotic, proinflammatoric, and profibrotic processes. Exercise training was associated with a prolonged right atrial effective refractory period. We could not induce arrhythmias by programmed stimulation in any groups. We found decreased expression of potassium channels. Female gender was associated with lower profibrotic expression and collagen density. Long-term, balanced exercise training-induced atrial hypertrophy is not associated with harmful electrical remodeling, and no inflammatory or profibrotic response was observed in the atrium of exercised rats.
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Affiliation(s)
- Attila Oláh
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
- Correspondence: ; Tel.: +36-1-458-6810; Fax: +36-1-458-6842
| | - Bálint András Barta
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
| | - Alex Ali Sayour
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
| | - Mihály Ruppert
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
| | - Eszter Virág-Tulassay
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
| | - Julianna Novák
- HCEMM-SU Cardiometabolic Immunology Research Group, Semmelweis University; Nagyvárad tér 4, 1089 Budapest, Hungary; (J.N.); (Z.V.V.)
| | - Zoltán V. Varga
- HCEMM-SU Cardiometabolic Immunology Research Group, Semmelweis University; Nagyvárad tér 4, 1089 Budapest, Hungary; (J.N.); (Z.V.V.)
- Department of Pharmacology and Pharmacotherapy, Semmelweis University; Nagyvárad tér 4, 1089 Budapest, Hungary;
| | - Péter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University; Nagyvárad tér 4, 1089 Budapest, Hungary;
- Pharmahungary Group, 6722 Szeged, Hungary
| | - Béla Merkely
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
| | - Tamás Radovits
- Heart and Vascular Center, Semmelweis University; Városmajor str. 68, 1122 Budapest, Hungary; (B.A.B.); (A.A.S.); (M.R.); (E.V.-T.); (B.M.); (T.R.)
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3
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Lozano WM, Parra G, Arias-Mutis OJ, Zarzoso M. Exercise Training Protocols in Rabbits Applied in Cardiovascular Research. Animals (Basel) 2020; 10:ani10081263. [PMID: 32722314 PMCID: PMC7459864 DOI: 10.3390/ani10081263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 11/20/2022] Open
Abstract
Simple Summary Several animal models have been used to understand the physiological adaptations produced by exercise training in the healthy and diseased cardiovascular system. Among those, the protocols for acute and chronic exercise in rabbits present several advantages compared to other large animal models. In addition, the rabbit model has important physiological similarities with humans. On the other hand, the design of the training protocol is a key factor to induce the physiological adaptations. Here, we review the different training protocols used in rabbits and the different physiological adaptations produced in the cardiovascular system, in normal and pathological conditions. Abstract Rabbit exercise protocols allow for the evaluation of physiological and biomechanical changes and responses to episodes of acute or chronic exercise. The observed physiological changes are normal responses to stress, that is, adaptive responses to maintain or restore homeostasis after acute exercise. Indeed, the rabbit model is advantageous since (a) it has important physiological similarities in terms of the functioning of multiple organ systems, and can quickly induce alterations in pathophysiological conditions that resemble those of humans, and (b) it allows the implementation of a low-cost model in comparison with other large animals. When designing an exercise training protocol for rabbits, it is important to consider variables such as race, gender, age and, especially, training parameters such as volume, intensity, or rest, among others, to determine the outcome of the research. Therefore, the objective of this review is to identify and analyze exercise training protocols in rabbits in different experimental applications and the various physiological adaptations that are presented, with special focus in cardiovascular adaptations.
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Affiliation(s)
- Wilson M. Lozano
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
| | - Germán Parra
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
- INCLIVA, Instituto de Investigación Sanitaria, 46010 Valencia, Spain
| | - Oscar J. Arias-Mutis
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
- INCLIVA, Instituto de Investigación Sanitaria, 46010 Valencia, Spain
- CIBERCV, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Manuel Zarzoso
- Department of Physiotherapy, Universitat de València, 46010 Valencia, Spain
- Correspondence: ; Tel.: +34-963-983-853
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Clauss S, Bleyer C, Schüttler D, Tomsits P, Renner S, Klymiuk N, Wakili R, Massberg S, Wolf E, Kääb S. Animal models of arrhythmia: classic electrophysiology to genetically modified large animals. Nat Rev Cardiol 2020; 16:457-475. [PMID: 30894679 DOI: 10.1038/s41569-019-0179-0] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Arrhythmias are common and contribute substantially to cardiovascular morbidity and mortality. The underlying pathophysiology of arrhythmias is complex and remains incompletely understood, which explains why mostly only symptomatic therapy is available. The evaluation of the complex interplay between various cell types in the heart, including cardiomyocytes from the conduction system and the working myocardium, fibroblasts and cardiac immune cells, remains a major challenge in arrhythmia research because it can be investigated only in vivo. Various animal species have been used, and several disease models have been developed to study arrhythmias. Although every species is useful and might be ideal to study a specific hypothesis, we suggest a practical trio of animal models for future use: mice for genetic investigations, mechanistic evaluations or early studies to identify potential drug targets; rabbits for studies on ion channel function, repolarization or re-entrant arrhythmias; and pigs for preclinical translational studies to validate previous findings. In this Review, we provide a comprehensive overview of different models and currently used species for arrhythmia research, discuss their advantages and disadvantages and provide guidance for researchers who are considering performing in vivo studies.
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Affiliation(s)
- Sebastian Clauss
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany. .,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany.
| | - Christina Bleyer
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Dominik Schüttler
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Philipp Tomsits
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Simone Renner
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZD (German Centre for Diabetes Research), Neuherberg, Germany
| | - Nikolai Klymiuk
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians University Munich (LMU), Munich, Germany
| | - Reza Wakili
- Universitätsklinikum Essen, Westdeutsches Herz- und Gefäßzentrum Essen, Essen, Germany
| | - Steffen Massberg
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Eckhard Wolf
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany.,Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZD (German Centre for Diabetes Research), Neuherberg, Germany
| | - Stefan Kääb
- Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
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Such-Miquel L, Brines L, Alberola AM, Zarzoso M, Chorro FJ, Guerrero J, Parra G, Gallego N, Soler C, Del Canto I, Guill A, Such L. Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart. PLoS One 2018; 13:e0209085. [PMID: 30562383 PMCID: PMC6298659 DOI: 10.1371/journal.pone.0209085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/19/2018] [Indexed: 11/19/2022] Open
Abstract
A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1μM), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activation complexity, as an approach to myocardial heterogeneity and stability. The VV interval was longer in the trained group than in the control group both prior to atropine (78±10 vs. 68±10 ms) and after atropine (76±8 vs. 67±10 ms). Likewise, FRPVF was longer in the trained group than in the control group both prior to and after atropine (53±8 vs. 42±7 ms and 50±6 vs. 40±6 ms, respectively), and atropine did not modify FRPVF. The CV of FRPVF was lower in the trained group than in the control group prior to atropine (12.5±1.5% vs. 15.1±3.8%) and, decreased after atropine (15.1±3.8% vs. 12.2±2.4%) in the control group. The trained group showed higher NE values before (0.40±0.04 vs. 0.36±0.05) and after atropine (0.37±0.04 vs. 0.34±0.06; p = 0.08). Training decreased the CV of NE both before (23.3±2% vs. 25.2±4%; p = 0.08) and after parasympathetic blockade (22.6±1% vs. 26.1±5%). Cholinergic blockade did not modify these parameters within the control and trained groups. Activation complexity was lower in the trained than in the control animals before atropine (34±8 vs. 41±5), and increased after atropine in the control group (41±5 vs. 48±9, respectively). Thus, training decreases the intrinsic heterogeneity of the myocardium, increases electrophysiological stability, and prevents some modifications due to muscarinic block.
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Affiliation(s)
- Luis Such-Miquel
- Department of Physiotherapy, Universitat de València, Valencia, Spain
- Health Research Institute (INCLIVA), Valencia, Spain
| | - Laia Brines
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Physiology, Universitat de València, Valencia, Spain
| | - Antonio M. Alberola
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Physiology, Universitat de València, Valencia, Spain
| | - Manuel Zarzoso
- Department of Physiotherapy, Universitat de València, Valencia, Spain
- Health Research Institute (INCLIVA), Valencia, Spain
| | - Francisco J. Chorro
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Medicine, Universitat de València, Valencia, Spain
| | - Juan Guerrero
- Department of Electronic Engineering, Universitat de València, Valencia, Spain
| | - Germán Parra
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Physiology, Universitat de València, Valencia, Spain
| | | | - Carlos Soler
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Physiology, Universitat de València, Valencia, Spain
| | | | - Antonio Guill
- ITACA, Universitat Politècnica de València, Valencia, Spain
| | - Luis Such
- Health Research Institute (INCLIVA), Valencia, Spain
- Department of Physiology, Universitat de València, Valencia, Spain
- * E-mail:
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Boyett MR, Wang Y, Nakao S, Ariyaratnam J, Hart G, Monfredi O, D'Souza A. Point: Exercise training-induced bradycardia is caused by changes in intrinsic sinus node function. J Appl Physiol (1985) 2017; 123:684-685. [PMID: 28684593 DOI: 10.1152/japplphysiol.00604.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 12/15/2022] Open
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Vargas RA. Effects of GABA, Neural Regulation, and Intrinsic Cardiac Factors on Heart Rate Variability in Zebrafish Larvae. Zebrafish 2017; 14:106-117. [DOI: 10.1089/zeb.2016.1365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Rafael Antonio Vargas
- Departamento de Ciencias Fisiológicas, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia
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Parkin ML, Lim K, Burke SL, Head GA. Comparison in Conscious Rabbits of the Baroreceptor-Heart Rate Reflex Effects of Chronic Treatment with Rilmenidine, Moxonidine, and Clonidine. Front Physiol 2016; 7:522. [PMID: 27895591 PMCID: PMC5108798 DOI: 10.3389/fphys.2016.00522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/24/2016] [Indexed: 11/13/2022] Open
Abstract
We investigated the effects of chronic subcutaneous treatment with centrally-acting antihypertensive agents moxonidine, rilmenidine, and clonidine on the baroreflex control of heart rate (HR) in conscious normotensive rabbits over 3 weeks. Infusions of phenylephrine and nitroprusside were performed at week 0 and at weeks 1 and 3 of treatment to determine mean arterial pressure (MAP)-HR baroreflex relationships. A second curve was performed after intravenous methscopolamine to determine the sympathetic baroreflex relationship. The vagal component of the reflex was determined by subtracting the sympathetic curve from the intact curve. Clonidine and moxonidine (both 1 mg/kg/day), and rilmenidine (5 mg/kg/day), reduced MAP by 13 ± 3, 15 ± 2, and 13 ± 2 mmHg, respectively, but had no effect on HR over the 3-week treatment period. Whilst all three antihypertensive agents shifted baroreflex curves to the left, parallel to the degree of hypotension, moxonidine and rilmenidine decreased the vagal contribution to the baroreflex by decreasing the HR range of the reflex but moxonidine also increased sympathetic baroreflex range and sensitivity. By contrast clonidine had little chronic effect on the cardiac baroreflex. The present study shows that second generation agents moxonidine and rilmenidine but not first generation agent clonidine chronically shift the balance of baroreflex control of HR toward greater sympathetic and lesser vagal influences. These changes if translated to hypertensive subjects, may not be particularly helpful in view of the already reduced vagal contribution in hypertension.
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Affiliation(s)
- Monique L Parkin
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
| | - Kyungjoon Lim
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
| | - Sandra L Burke
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
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Billman GE, Cagnoli KL, Csepe T, Li N, Wright P, Mohler PJ, Fedorov VV. Exercise training-induced bradycardia: evidence for enhanced parasympathetic regulation without changes in intrinsic sinoatrial node function. J Appl Physiol (1985) 2015; 118:1344-55. [PMID: 25749448 PMCID: PMC4451292 DOI: 10.1152/japplphysiol.01111.2014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/28/2015] [Indexed: 01/17/2023] Open
Abstract
The mechanisms responsible for exercise-induced reductions in baseline heart rate (HR), known as training bradycardia, remain controversial. Therefore, changes in cardiac autonomic regulation and intrinsic sinoatrial nodal (SAN) rate were evaluated using dogs randomly assigned to either a 10- to 12-wk exercise training (Ex, n = 15) or an equivalent sedentary period (Sed, n = 10). Intrinsic HR was revealed by combined autonomic nervous system (ANS) blockade (propranolol + atropine, iv) before and after completion of the study. At the end of the study, SAN function was further evaluated by examining the SAN recovery time (SNRT) following rapid atrial pacing and the response to adenosine in anesthetized animals. As expected, both the response to submaximal exercise and baseline HR significantly (P < 0.01) decreased, and heart rate variability (HRV; e.g., high-frequency R-R interval variability) significantly (P < 0.01) increased in the Ex group but did not change in the Sed group. Atropine also induced significantly (P < 0.01) greater reductions in HRV in the Ex group compared with the Sed group; propranolol elicited similar HR and HRV changes in both groups. In contrast, neither intrinsic HR (Ex before, 141.2 ± 6.7; Ex after, 146.0 ± 8.0 vs. Sed before, 143.3 ± 11.1; Sed after, 141.0 ± 11.3 beats per minute), the response to adenosine, corrected SNRT, nor atrial fibrosis and atrial fibrillation inducibility differed in the Ex group vs. the Sed group. These data suggest that in a large-animal model, training bradycardia results from an enhanced cardiac parasympathetic regulation and not from changes in intrinsic properties of the SAN.
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Affiliation(s)
- George E Billman
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and
| | - Kristen L Cagnoli
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
| | - Thomas Csepe
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
| | - Ning Li
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
| | - Patrick Wright
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and Deaprtment of Internal Medicine, The Ohio State University, Columbus, Ohio
| | - Vadim V Fedorov
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and
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10
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Bradycardia: changes in intrinsic rate rather than cardiac autonomic modulation. Clin Auton Res 2013; 23:343. [PMID: 23884700 DOI: 10.1007/s10286-013-0208-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
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11
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The training-induced changes on automatism, conduction and myocardial refractoriness are not mediated by parasympathetic postganglionic neurons activity. Eur J Appl Physiol 2011; 112:2185-93. [PMID: 21968799 DOI: 10.1007/s00421-011-2189-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
The purpose of this study is to test the role that parasympathetic postganglionic neurons could play on the adaptive electrophysiological changes produced by physical training on intrinsic myocardial automatism, conduction and refractoriness. Trained rabbits were submitted to a physical training protocol on treadmill during 6 weeks. The electrophysiological study was performed in an isolated heart preparation. The investigated myocardial properties were: (a) sinus automatism, (b) atrioventricular and ventriculoatrial conduction, (c) atrial, conduction system and ventricular refractoriness. The parameters to study the refractoriness were obtained by means of extrastimulus test at four different pacing cycle lengths (10% shorter than spontaneous sinus cycle length, 250, 200 and 150 ms) and (d) mean dominant frequency (DF) of the induced ventricular fibrillation (VF), using a spectral method. The electrophysiological protocol was performed before and during continuous atropine administration (1 μM), in order to block cholinergic receptors. Cholinergic receptor blockade did not modify either the increase in sinus cycle length, atrioventricular conduction and refractoriness (left ventricular and atrioventricular conduction system functional refractory periods) or the decrease of DF of VF. These findings reveal that the myocardial electrophysiological modifications produced by physical training are not mediated by intrinsic cardiac parasympathetic activity.
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12
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A study of the physiological consequences of sympathetic denervation of the heart caused by the arterial switch procedure. Cardiol Young 2010; 20:150-8. [PMID: 20219152 DOI: 10.1017/s1047951109990643] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND The arterial switch operation is the corrective operation for transposition of the great arteries, defined as the combination of concordant atrioventricular and discordant ventriculo-arterial connections, but there have been concerns about silent subendocardial ischaemia on exercise and coronary artery growth. The arterial switch divides the majority of the sympathetic nerves entering the heart; we have studied the effects of coronary flow and sensitivity to catecholamine stimulation in an animal model. METHODS A total of 10 piglets were operated on cardiopulmonary bypass with section and resuturing of aortic trunk, pulmonary artery and both coronary arteries, with 13 sham-operated controls. After 5-7 weeks of recovery, seven simulated switch survivors and 13 controls were studied. RESULTS Basal heart rate was significantly higher in switch piglets: in vivo mean (standard deviation) 112 (12) versus sham 100 (10) beats per minute, (p = 0.042); in vitro (Langendorff preparation): 89 (9) versus sham 73 (8) beats per minute (p = 0.0056). In vivo maximal heart rate in response to epinephrine was increased in switch piglets, 209 (13) versus 190 (17) beats per minute (p = 0.044). In vitro dose-response curves to norepinephrine were shifted leftward and upwards (p = 0.0014), with an 80% increase in heart rate induced by 0.095 (0.053) norepinephrine micromole per litre perfusate in switch hearts versus 0.180 (0.035) norepinephrine micromole per litre (p = 0.023). Increase in coronary flow on norepinephrine stimulation and maximal coronary flow were significantly reduced in switch hearts: 0.3 (0.2) versus 0.8 (0.4) millilitre per gram heart weight (p = 0.045) and 2.5 (0.4) versus 3.1 (0.4) millilitre per gram heart (p = 0.030), respectively. CONCLUSIONS A combination of increased intrinsic heart rate, increased sensitivity to chronotropic actions of norepinephrine, and a decreased maximal coronary flow creates potential for a mismatch between perfusion and energy demands.
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Such L, Alberola AM, Such-Miquel L, López L, Trapero I, Pelechano F, Gómez-Cabrera MC, Tormos A, Millet J, Chorro FJ. Effects of chronic exercise on myocardial refractoriness: a study on isolated rabbit heart. Acta Physiol (Oxf) 2008; 193:331-9. [PMID: 18346209 DOI: 10.1111/j.1748-1716.2008.01851.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To determine whether chronic physical training increases atrial and ventricular refractoriness in isolated rabbit heart. METHODS Trained rabbits were submitted to a protocol of treadmill running. The electrophysiological parameters of refractoriness investigated in an isolated heart preparation were: (1) atrial effective refractory period (AERP) and atrial functional refractory period and ventricular effective and functional refractory periods (VERP and VFRP) using the extrastimulus technique at four different pacing cycle lengths; (2) the dominant frequency (DF) of ventricular fibrillation (VF). A multi-electrode plaque containing 256 electrodes and a spectral method were used to obtain the mean, maximum and minimum DF of VF. Sinus cycle length of the isolated hearts was determined as an electrophysiological parameter of training. In vivo heart rate, myocardial heat shock proteins (HSP60) and inducible nitric oxide synthase were also determined in some animals as electrophysiological and biochemical markers of training respectively. RESULTS VERP and VFRP were longer in the trained group than in the control group. The mean DF of VF was lower in the trained group than in the control group. Despite the fact that training did not significantly modify the AERP, it tended to be longer in the trained group (P = 0.09). CONCLUSION Training seems to increase the electrical stability of ventricular myocardium. As the electrophysiological modifications were exhibited in hearts not submitted to extrinsic nervous system or humoral influences, they are, at least in part, intrinsic modifications. These electrophysiological data also suggest that training could protect against reentrant ventricular arrhythmias.
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Affiliation(s)
- L Such
- Department of Physiology, University of Valencia, Valencia, Spain.
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Gul M, Demircan B, Taysi S, Oztasan N, Gumustekin K, Siktar E, Polat MF, Akar S, Akcay F, Dane S. Effects of endurance training and acute exhaustive exercise on antioxidant defense mechanisms in rat heart. Comp Biochem Physiol A Mol Integr Physiol 2006; 143:239-45. [PMID: 16426880 DOI: 10.1016/j.cbpa.2005.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Revised: 11/28/2005] [Accepted: 11/30/2005] [Indexed: 12/21/2022]
Abstract
We investigated whether 8-week treadmill training strengthens antioxidant enzymes and decreases lipid peroxidation in rat heart. The effects of acute exhaustive exercise were also investigated. Male rats (Rattus norvegicus, Sprague-Dawley strain) were divided into trained and untrained groups. Both groups were further divided equally into two groups where the rats were studied at rest and immediately after exhaustive exercise. Endurance training consisted of treadmill running 1.5 h day(-1), 5 days week(-1) for 8 weeks. For acute exhaustive exercise, graded treadmill running was conducted. Malondialdehyde level in heart tissue was not affected by acute exhaustive exercise in untrained and trained rats. The activities of glutathione peroxidase and glutathione reductase enzymes decreased by both acute exercise and training. Glutathione S-transferase and catalase activities were not affected. Total and non-enzymatic superoxide scavenger activities were not affected either. Superoxide dismutase activity decreased by acute exercise in untrained rats; however, this decrease was not observed in trained rats. Our results suggested that rat heart has sufficient antioxidant enzyme capacity to cope with exercise-induced oxidative stress, and adaptive changes in antioxidant enzymes due to endurance training are limited.
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Affiliation(s)
- Mustafa Gul
- Department of Physiology, Faculty of Medicine, Ataturk University, 25240, Erzurum, Turkey.
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Collins HL, Rodenbaugh DW, DiCarlo SE. Spinal cord injury alters cardiac electrophysiology and increases the susceptibility to ventricular arrhythmias. PROGRESS IN BRAIN RESEARCH 2006; 152:275-88. [PMID: 16198707 DOI: 10.1016/s0079-6123(05)52018-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The autonomic nervous system modulates cardiac electrophysiology and abnormalities of autonomic function are known to increase the risk of ventricular arrhythmias. The abnormal and unstable autonomic control of the cardiovascular system following spinal cord injury also is well known. For example, individuals with mid-thoracic spinal cord injury have elevated resting heart rates, increased blood pressure variability, episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia, and elevated sympathetic activity above the level of the lesion. Furthermore, cardiovascular morbidity and mortality are high in individuals with spinal cord injuries due to a relatively sedentary lifestyle and higher prevalence of other cardiovascular risk factors, including obesity and diabetes. Therefore, spinal cord injury may alter cardiac electrophysiology and increase the risk for ventricular arrhythmias. In this chapter, we discuss how the autonomic changes associated with cord injury can influence cardiac electrophysiology and the susceptibility to ventricular arrhythmias.
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Affiliation(s)
- Heidi L Collins
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Rodenbaugh DW, Collins HL, Nowacek DG, DiCarlo SE. Increased susceptibility to ventricular arrhythmias is associated with changes in Ca2+ regulatory proteins in paraplegic rats. Am J Physiol Heart Circ Physiol 2003; 285:H2605-13. [PMID: 12881214 DOI: 10.1152/ajpheart.00319.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Paraplegia may increase susceptibility to ventricular arrhythmias by altering the autonomic control of the heart. Altered cardiac autonomic control has been documented to change the expression of genes that encode cardiac Ca2+ regulatory proteins. Therefore, we tested the hypothesis that paraplegia alters cardiac electrophysiology with concomitant changes in Ca2+ regulatory proteins in a manner that increases the susceptibility to ventricular arrhythmias. To test this hypothesis, intact (n = 10) and paraplegic (n = 6) male Wistar rats were chronically instrumented to measure atrioventricular (AV) interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle (cSNRT), Wenckebach cycle length (WCL), and the electrical stimulation threshold to induce ventricular arrhythmias. In addition, relative protein abundance and mRNA expression for sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA), phospholamban, and the Na/Ca exchanger were determined in intact (n = 8) and paraplegic (n = 8) rats. Paraplegia significantly (P < 0.05) reduced AV interval (-25%), sinus cycle length (-24%), SNRT (-28%), cSNRT (-53%), WCL (-19%), and the electrical stimulation threshold to induce ventricular arrhythmia (-48%). Paraplegia significantly increased the relative protein abundances of SERCA (45%) and the Na/Ca exchanger (40%) and decreased phospholamban levels (-28%). In contrast, only the relative mRNA expression of the Na/Ca exchanger was increased (25%) in paraplegic rats. These data demonstrate that paraplegia enhances cardiac electrophysiological properties and alters Ca2+ regulatory proteins in a manner that increases susceptibility to ventricular arrhythmias.
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Affiliation(s)
- David W Rodenbaugh
- Department of Physiology, School of Medicine, Wayne State University, 540 East Canfield Ave., Detroit, MI 48201, USA
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