title: Chloride channel inhibition prevents ROS-dependent apoptosis induced by ischemia-reperfusion in mouse cardiomyocytes.
abstract: Apoptosis of cardiomyocytes following ischemia and reperfusion is of clinical importance. However, little is known about the mechanism by which it is induced. Recently, essential roles of a Cl- channel whose activity triggers the apoptotic volume decrease and of reactive oxygen species (ROS) in activation of this channel have been identified in mitochondrion-mediated apoptosis. Therefore, in this study, involvement of Cl- channels and ROS in apoptosis was studied in primary mouse cardiomyocyte cultures subjected to ischemia-reperfusion. Apoptotic cell death as measured by caspase-3 activation, chromatin condensation, DNA laddering, and cell viability reduction was observed tens of hours after reperfusion but never immediately after ischemia. A non-selective Cl-channel blocker (DIDS or NPPB) rescued cells from apoptotic death when applied during the reperfusion, but not ischemia, period. Another blocker relatively specific to the volume-sensitive outwardly rectifying (VSOR) Cl-channel (phloretin) was also effective in protecting ischemic cardiomyocytes from apoptosis induced by reperfusion. A profound increase in intracellular ROS was detected in cardiomyocytes during the reperfusion, but not ischemia, period. Scavengers for ROS, H2O2 and superoxide all inhibited apoptosis induced by ischemia-reperfusion. Thus, it is concluded that the mechanism by which cardiomyocyte apoptosis is induced by ischemia-reperfusion involves VSOR Cl- channel activity and intracellular ROS production.
authors.affiliation: Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Uramoto
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Okada
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors* / Q000502:physiology; D016166:Free Radical Scavengers / Q000494:pharmacology; D051379:Mice; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D010693:Phloretin / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D018118:Chloride Channels; D016166:Free Radical Scavengers; D009579:Nitrobenzoates; D017382:Reactive Oxygen Species; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D010693:Phloretin