title: Ionic channels underlying the ventricular action potential in zebrafish embryo.
abstract: Over the last years zebrafish has become a popular model in the study of cardiac physiology, pathology and pharmacology. Recently, the application of the 3Rs regulation and the characteristics of the embryo have reduced the use of adult zebrafish use in many studies. However, the zebrafish embryo cardiac physiology is poorly characterized since most works have used indirect techniques and direct recordings of cardiac action potential and ionic currents are scarce. In order to optimize the zebrafish embryo model, we used electrophysiological, pharmacological and immunofluorescence tools to identify the characteristics and the ionic channels involved in the ventricular action potentials of zebrafish embryos. The application of Na(+) or T-type Ca(+2) channel blockers eliminated the cardiac electrical activity, indicating that the action potential upstroke depends on Na(+) and T-type Ca(+2) currents. The plateau phase depends on L-type Ca(+2) channels since it is abolished by specific blockade. The direct channel blockade indicates that the action potential repolarization and diastolic potential depends on ERG K(+) channels. The presence in the embryonic heart of the Nav1.5, Cav1.2, Cav3.2 and ERG channels was also confirmed by immunofluorescence, while the absence of effect of specific blockers and immunostaining indicate that two K(+) repolarizing currents present in human heart, Ito and IKs, are absent in the embryonic zebrafish heart. Our results describe the ionic channels present and its role in the zebrafish embryo heart and support the use of zebrafish embryos to study human diseases and their use for drug testing.
authors.affiliation: Department of Physiology, School of Pharmacy, University of the Basque Country UPV/EHU, Spain.
authors.forename: Aintzane
authors.initials: A
authors.lastname: Alday
authors.affiliation: Department of Physiology, School of Pharmacy, University of the Basque Country UPV/EHU, Spain; Lascaray Research Center, University of the Basque Country UPV/EHU, Spain.
authors.forename: Hiart
authors.initials: H
authors.lastname: Alonso
authors.affiliation: Department of Physiology, School of Pharmacy, University of the Basque Country UPV/EHU, Spain; Lascaray Research Center, University of the Basque Country UPV/EHU, Spain.
authors.forename: Monica
authors.initials: M
authors.lastname: Gallego
authors.affiliation: Department of Physiology, School of Pharmacy, University of the Basque Country UPV/EHU, Spain.
authors.forename: Janire
authors.initials: J
authors.lastname: Urrutia
authors.affiliation: Biobide S.L., San Sebastián, Spain.
authors.forename: Ainhoa
authors.initials: A
authors.lastname: Letamendia
authors.affiliation: Biobide S.L., San Sebastián, Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Callol
authors.affiliation: Department of Physiology, School of Pharmacy, University of the Basque Country UPV/EHU, Spain; Lascaray Research Center, University of the Basque Country UPV/EHU, Spain. Electronic address: oscar.casis@ehu.es.
authors.forename: Oscar
authors.initials: O
authors.lastname: Casis
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015027:Zebrafish
chemical_list: D002121:Calcium Channel Blockers; D007473:Ion Channels; D026941:Sodium Channel Blockers
keywords: Cardiac development; Depolarizing current; Electrophysiology; Repolarizing current