title: Optogenetic determination of the myocardial requirements for extrasystoles by cell type-specific targeting of ChannelRhodopsin-2.
abstract: Extrasystoles lead to several consequences, ranging from uneventful palpitations to lethal ventricular arrhythmias, in the presence of pathologies, such as myocardial ischemia. The role of working versus conducting cardiomyocytes, as well as the tissue requirements (minimal cell number) for the generation of extrasystoles, and the properties leading ectopies to become arrhythmia triggers (topology), in the normal and diseased heart, have not been determined directly in vivo. Here, we used optogenetics in transgenic mice expressing ChannelRhodopsin-2 selectively in either cardiomyocytes or the conduction system to achieve cell type-specific, noninvasive control of heart activity with high spatial and temporal resolution. By combining measurement of optogenetic tissue activation in vivo and epicardial voltage mapping in Langendorff-perfused hearts, we demonstrated that focal ectopies require, in the normal mouse heart, the simultaneous depolarization of at least 1,300-1,800 working cardiomyocytes or 90-160 Purkinje fibers. The optogenetic assay identified specific areas in the heart that were highly susceptible to forming extrasystolic foci, and such properties were correlated to the local organization of the Purkinje fiber network, which was imaged in three dimensions using optical projection tomography. Interestingly, during the acute phase of myocardial ischemia, focal ectopies arising from this location, and including both Purkinje fibers and the surrounding working cardiomyocytes, have the highest propensity to trigger sustained arrhythmias. In conclusion, we used cell-specific optogenetics to determine with high spatial resolution and cell type specificity the requirements for the generation of extrasystoles and the factors causing ectopies to be arrhythmia triggers during myocardial ischemia.
authors.affiliation: Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy;
authors.forename: Tania
authors.initials: T
authors.lastname: Zaglia
authors.affiliation: Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy;
authors.forename: Nicola
authors.initials: N
authors.lastname: Pianca
authors.affiliation: Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy;
authors.forename: Giulia
authors.initials: G
authors.lastname: Borile
authors.affiliation: Venetian Institute of Molecular Medicine, 35129 Padova, Italy;
authors.forename: Francesca
authors.initials: F
authors.lastname: Da Broi
authors.affiliation: Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Gottingen, Germany;
authors.forename: Claudia
authors.initials: C
authors.lastname: Richter
authors.affiliation: Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Neuroscience Institute, Consiglio Nazionale delle Ricerche, 35121 Padova, Italy;
authors.forename: Marina
authors.initials: M
authors.lastname: Campione
authors.affiliation: Heart Research Center Göttingen, Clinic of Cardiology and Pulmonology, University Medical Center, 37077 Gottingen, Germany; German Centre for Cardiovascular Research, partner site Göttingen, 37077 Gottingen, Germany;
authors.forename: Stephan E
authors.initials: SE
authors.lastname: Lehnart
authors.affiliation: Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Gottingen, Germany; Heart Research Center Göttingen, Clinic of Cardiology and Pulmonology, University Medical Center, 37077 Gottingen, Germany; German Centre for Cardiovascular Research, partner site Göttingen, 37077 Gottingen, Germany; Institute for Nonlinear Dynamics, Georg-August-Universität Göttingen, 37077 Gottingen, Germany;
authors.forename: Stefan
authors.initials: S
authors.lastname: Luther
authors.affiliation: Department of Cardiologic, Thoracic and Vascular Sciences, University of Padova, 35128 Padova, Italy;
authors.forename: Domenico
authors.initials: D
authors.lastname: Corrado
authors.affiliation: Aix Marseille University, CNRS Institut de Biologie du Développement de Marseille UMR 7288, 13288 Marseille, France.
authors.forename: Lucile
authors.initials: L
authors.lastname: Miquerol
authors.affiliation: Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy; Neuroscience Institute, Consiglio Nazionale delle Ricerche, 35121 Padova, Italy; marco.mongillo@unipd.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Mongillo
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D005117:Cardiac Complexes, Premature / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D000075402:Channelrhodopsins; D017630:Connexins / Q000378:metabolism; D003331:Coronary Vessels / Q000473:pathology / Q000503:physiopathology; D055724:Electrophysiological Phenomena; D006801:Humans; D019426:Integrases / Q000378:metabolism; D008026:Ligation; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D017202:Myocardial Ischemia / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D062308:Optogenetics / Q000379:methods*; D009928:Organ Specificity; D011690:Purkinje Fibers / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D000097003:Gap Junction alpha-5 Protein
chemical_list: D000075402:Channelrhodopsins; D017630:Connexins; D019426:Integrases; D000097003:Gap Junction alpha-5 Protein; C045073:Cre recombinase
keywords: Purkinje fiber; arrhythmia; cardiac ectopies; heart; optogenetics