title: Relevance of cardiomyocyte mechano-electric coupling to stretch-induced arrhythmias: optical voltage/calcium measurement in mechanically stimulated cells, tissues and organs.
abstract: Stretch-induced arrhythmias are multi-scale phenomena in which alterations in channel activities and/or calcium handling lead to the organ level derangement of the heart rhythm. To understand how cellular mechano-electric coupling (MEC) leads to stretch-induced arrhythmias at the organ level, we developed stretching devices and optical voltage/calcium measurement techniques optimized to each cardiac level. This review introduces these experimental techniques of (1) optical voltage measurement coupled with a carbon-fiber technique for single isolated cardiomyocytes, (2) optical voltage mapping combined with motion tracking technique for myocardial tissue/whole heart preparations and (3) real-time calcium imaging coupled with a laser optical trap technique for cardiomyocytes. Following the overview of each methodology, results are presented. We conclude that individual MEC in cardiomyocytes can be heterogeneous at the ventricular level, especially when moderate amplitude mechanical stretches are applied to the heart, and that this heterogeneous MEC can evoke focal excitation that develops into re-entrant arrhythmias.
authors.affiliation: Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA. Electronic address: seokin54@gmail.com.
authors.forename: Kinya
authors.initials: K
authors.lastname: Seo
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan. Electronic address: masashii@ncvc.go.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Inagaki
authors.affiliation: Division of Physical and Health Education, Graduate School of Education, The University of Tokyo, Tokyo 113-0033, Japan. Electronic address: hidaka@p.u-tokyo.ac.jp.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hidaka
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan. Electronic address: hanaff87@gmail.com.
authors.forename: Hana
authors.initials: H
authors.lastname: Fukano
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan. Electronic address: su91mach@ncvc.go.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan. Electronic address: hisada@mech.t.u-tokyo.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hisada
authors.affiliation: Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan; Department of Cardiovascular Medicine, Translational Systems Biology and Medicine Initiative, The University of Tokyo, Tokyo 113-8655, Japan. Electronic address: snishi-tky@umin.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nishimura
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan. Electronic address: sugiura@k.u-tokyo.ac.jp.
authors.forename: Seiryo
authors.initials: S
authors.lastname: Sugiura
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D056966:Excitation Contraction Coupling / Q000502:physiology*; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D032342:Muscle Cells; D009200:Myocardial Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D056969:Voltage-Sensitive Dye Imaging / Q000379:methods*
chemical_list: D002118:Calcium
keywords: Carbon-fiber; Commotio cordis; Mechano-electric coupling; Optical mapping; Optical trap; Stretch-induced arrhythmia