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Zabrodska E, Kvasilova A, Sedmera D, Olejnickova V. Electrical remodeling of atrioventricular junction: a study on retrogradely perfused chick embryonic heart. Am J Physiol Heart Circ Physiol 2024; 327:H555-H564. [PMID: 39028286 DOI: 10.1152/ajpheart.00115.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 07/10/2024] [Accepted: 07/12/2024] [Indexed: 07/20/2024]
Abstract
Atrioventricular (AV) accessory pathways (APs) provide additional electrical connections between the atria and ventricles, resulting in severe electrical disturbances. It is generally accepted that APs originate in the altered annulus fibrosus maturation in the late prenatal and perinatal period. However, current experimental methods cannot address their development in specific locations around the annulus fibrosus because of the inaccessibility of late fetal hearts for electrophysiological investigation under physiological conditions. In this study, we describe an approach for optical mapping of the retrogradely perfused chick heart in the last third of the incubation period. This system showed stability for electrophysiological measurement for several hours. This feature allowed analysis of the number and functionality of the APs separately in each clinically relevant position. Under physiological conditions, we also recorded the shortening of the AV delay with annulus fibrosus maturation and analyzed ventricular activation patterns after conduction through APs at specific locations. We observed a gradual regression of AP with an area-specific rate (left-sided APs disappeared first). The results also revealed a sudden drop in the number of active APs between embryonic days 16 and 18. Accessory myocardial AV connections were histologically documented in all positions around the annulus fibrosus even after hatching. The fact that no electrically active AP was present at this stage highlights the necessity of electrophysiological evaluation of accessory atrioventricular connections in studying AP formation.NEW & NOTEWORTHY We present the use of retrograde perfusion and optical mapping to investigate, for the first time, the regression of accessory pathways during annulus fibrosus maturation, separately examining each clinically relevant location. The system enables measurements under physiological conditions and demonstrates long-lasting stability compared with other approaches. This study offers applications of the model to investigate electrical and/or functional development in late embryonic development without concern about heart viability.
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Affiliation(s)
- Eva Zabrodska
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Alena Kvasilova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - David Sedmera
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Veronika Olejnickova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
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Shiels HA. Avian cardiomyocyte architecture and what it reveals about the evolution of the vertebrate heart. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210332. [PMID: 36189815 PMCID: PMC9527935 DOI: 10.1098/rstb.2021.0332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/02/2022] [Indexed: 11/17/2022] Open
Abstract
Bird cardiomyocytes are long, thin and lack transverse (t)-tubules, which is akin to the cardiomyocyte morphology of ectothermic non-avian reptiles, who are typified by low maximum heart rates and low pressure development. However, birds can achieve greater contractile rates and developed pressures than mammals, whose wide cardiomyocytes contain a dense t-tubular network allowing for uniform excitation-contraction coupling and strong contractile force. To address this apparent paradox, this paper functionally links recent electrophysiological studies on bird cardiomyocytes with decades of ultrastructure measurements. It shows that it is the strong transsarcolemmal Ca2+ influx via the L-type Ca2+ current (ICaL) and the high gain of Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR), coupled with an internal SR Ca2+ release relay system, that facilitates the strong fast contractions in the long thin bird cardiomyocytes, without the need for t-tubules. The maintenance of an elongated myocyte morphology following the post-hatch transition from ectothermy to endothermy in birds is discussed in relation to cardiac load, myocyte ploidy, and cardiac regeneration potential in adult cardiomyocytes. Overall, the paper shows how little we know about cellular Ca2+ dynamics in the bird heart and suggests how increased research efforts in this area would provide vital information in our quest to understand the role of myocyte architecture in the evolution of the vertebrate heart. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'. Please see glossary at the end of the paper for definitions of specialized terms.
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Affiliation(s)
- Holly A. Shiels
- Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
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Abramochkin DV, Filatova TS, Pustovit KB, Voronina YA, Kuzmin VS, Vornanen M. Ionic currents underlying different patterns of electrical activity in working cardiac myocytes of mammals and non-mammalian vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2022; 268:111204. [PMID: 35346823 DOI: 10.1016/j.cbpa.2022.111204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 12/19/2022]
Abstract
The orderly contraction of the vertebrate heart is determined by generation and propagation of cardiac action potentials (APs). APs are generated by the integrated activity of time- and voltage-dependent ionic channels which carry inward Na+ and Ca2+ currents, and outward K+ currents. This review compares atrial and ventricular APs and underlying ion currents between different taxa of vertebrates. We have collected literature data and attempted to find common electrophysiological features for two or more vertebrate groups, show differences between taxa and cardiac chambers, and indicate gaps in the existing data. Although electrical excitability of the heart in all vertebrates is based on the same superfamily of channels, there is a vast variability of AP waveforms between atrial and ventricular myocytes, between different species of the same vertebrate class and between endothermic and ectothermic animals. The wide variability of AP shapes is related to species-specific differences in animal size, heart rate, stage of ontogenetic development, excitation-contraction coupling, temperature and oxygen availability. Some of the differences between taxa are related to evolutionary development of genomes, which appear e.g. in the expression of different Na+ and K+ channel orthologues in cardiomyocytes of vertebrates. There is a wonderful variability of AP shapes and underlying ion currents with which electrical excitability of vertebrate heart can be generated depending on the intrinsic and extrinsic conditions of animal body. This multitude of ionic mechanisms provides excellent material for studying how the function of the vertebrate heart can adapt or acclimate to prevailing physiological and environmental conditions.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia.
| | - Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Ksenia B Pustovit
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Yana A Voronina
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, 3(rd) Cherepkovskaya str., 15A, Moscow, Russia
| | - Vladislav S Kuzmin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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Boukens BJD, Joyce W, Kristensen DL, Hooijkaas I, Jongejan A, Wang T, Jensen B. Catecholamines are key modulators of ventricular repolarization patterns in the ball python (Python regius). J Gen Physiol 2022; 154:212914. [PMID: 34910097 PMCID: PMC8679508 DOI: 10.1085/jgp.202012761] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/28/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022] Open
Abstract
Ectothermic vertebrates experience daily changes in body temperature, and anecdotal observations suggest these changes affect ventricular repolarization such that the T-wave in the ECG changes polarity. Mammals, in contrast, can maintain stable body temperatures, and their ventricular repolarization is strongly modulated by changes in heart rate and by sympathetic nervous system activity. The aim of this study was to assess the role of body temperature, heart rate, and circulating catecholamines on local repolarization gradients in the ectothermic ball python (Python regius). We recorded body-surface electrocardiograms and performed open-chest high-resolution epicardial mapping while increasing body temperature in five pythons, in all of which there was a change in T-wave polarity. However, the vector of repolarization differed between individuals, and only a subset of leads revealed T-wave polarity change. RNA sequencing revealed regional differences related to adrenergic signaling. In one denervated and Ringer's solution-perfused heart, heating and elevated heart rates did not induce change in T-wave polarity, whereas noradrenaline did. Accordingly, electrocardiograms in eight awake pythons receiving intra-arterial infusion of the β-adrenergic receptor agonists adrenaline and isoproterenol revealed T-wave inversion in most individuals. Conversely, blocking the β-adrenergic receptors using propranolol prevented T-wave change during heating. Our findings indicate that changes in ventricular repolarization in ball pythons are caused by increased tone of the sympathetic nervous system, not by changes in temperature. Therefore, ventricular repolarization in both pythons and mammals is modulated by evolutionary conserved mechanisms involving catecholaminergic stimulation.
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Affiliation(s)
- Bastiaan J D Boukens
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - William Joyce
- Department of Biology, Zoophysiology, Aarhus University, Aarhus, Denmark
| | | | - Ingeborg Hooijkaas
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Aldo Jongejan
- University of Amsterdam, Amsterdam UMC, Department of Epidemiology & Data Science, Amsterdam, The Netherlands
| | - Tobias Wang
- Department of Biology, Zoophysiology, Aarhus University, Aarhus, Denmark
| | - Bjarke Jensen
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
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Little AG, Pamenter ME, Sitaraman D, Templeman NM, Willmore WG, Hedrick MS, Moyes CD. WITHDRAWN: Utilizing comparative models in biomedical research. Comp Biochem Physiol A Mol Integr Physiol 2021; 256:110938. [PMID: 33737041 DOI: 10.1016/j.cbpa.2021.110938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The Publisher regrets that this article is an accidental duplication of an article that has already been published in Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, Volume 255, 2021, 110593, https://doi.org/10.1016/j.cbpb.2021.110593. The duplicate article has therefore been withdrawn.
The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
| | | | - Divya Sitaraman
- Department of Psychology, California State University, East Bay, Hayward, CA, USA
| | | | | | - Michael S Hedrick
- Department of Biological Sciences, California State University, East Bay, Hayward, CA, USA.
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Little AG, Pamenter ME, Sitaraman D, Templeman NM, Willmore WG, Hedrick MS, Moyes CD. Utilizing comparative models in biomedical research. Comp Biochem Physiol B Biochem Mol Biol 2021; 255:110593. [PMID: 33779562 DOI: 10.1016/j.cbpb.2021.110593] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This review serves as an introduction to a Special Issue of Comparative Biochemistry and Physiology, focused on using non-human models to study biomedical physiology. The concept of a model differs across disciplines. For example, several models are used primarily to gain an understanding of specific human pathologies and disease states, whereas other models may be focused on gaining insight into developmental or evolutionary mechanisms. It is often the case that animals initially used to gain knowledge of some unique biochemical or physiological process finds foothold in the biomedical community and becomes an established model. The choice of a particular model for biomedical research is an ongoing process and model validation must keep pace with existing and emerging technologies. While the importance of non-mammalian models, such as Caenorhabditis elegans, Drosophila melanogaster, Danio rerio and Xenopus laevis, is well known, we also seek to bring attention to emerging alternative models of both invertebrates and vertebrates, which are less established but of interest to the comparative biochemistry and physiology community.
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Affiliation(s)
| | | | - Divya Sitaraman
- Department of Psychology, California State University, East Bay, Hayward, CA, USA
| | | | | | - Michael S Hedrick
- Department of Biological Sciences, California State University, East Bay, Hayward, CA, USA
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Offerhaus JA, Snelderwaard PC, Algül S, Faber JW, Riebel K, Jensen B, Boukens BJ. High heart rate associated early repolarization causes J-waves in both zebra finch and mouse. Physiol Rep 2021; 9:e14775. [PMID: 33709567 PMCID: PMC7953022 DOI: 10.14814/phy2.14775] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 11/24/2022] Open
Abstract
High heart rates are a feature of small endothermic—or warm‐blooded—mammals and birds. In small mammals, the QT interval is short, and local ventricular recordings reveal early repolarization that coincides with the J‐wave on the ECG, a positive deflection following the QRS complex. Early repolarization contributes to short QT‐intervals thereby enabling brief cardiac cycles and high heart rates. We therefore hypothesized high hearts rates associate with early repolarization and J‐waves on the ECG of endothermic birds. We tested this hypothesis by comparing isolated hearts of zebra finches and mice and recorded pseudo‐ECGs and optical action potentials (zebra finch, n = 8; mouse, n = 8). In both species, heart rate exceeded 300 beats per min, and total ventricular activation was fast (QRS < 10 ms). Ventricular activation progressed from the left to the right ventricle in zebra finch, whereas it progressed from apex‐to‐base in mouse. In both species, the early repolarization front followed the activation front, causing a positive J‐wave in the pseudo‐ECG. Inhibition of early repolarization by 4‐aminopyridine reduced J‐wave amplitude in both species. Action potential duration was similar between ventricles in zebra finch, whereas in mouse the left ventricular action potential was longer. Accordingly, late repolarization had opposite directions in zebra finch (left‐right) and mouse (right‐left). This caused a similar direction for the zebra finch J‐wave and T‐wave, whereas in the mouse they were discordant. Our findings demonstrate that early repolarization and the associated J‐wave may have evolved by convergence in association with high heart rates.
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Affiliation(s)
- Joost A Offerhaus
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | | | - Sila Algül
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Jaeike W Faber
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Katharina Riebel
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Bastiaan J Boukens
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands.,Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
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