title: Donepezil attenuated oxygen-glucose deprivation insult by blocking Kv2.1 potassium channels.
abstract: Excessive K(+) efflux via activated voltage-gated K(+) channels (Kv channels) and the consequent intracellular K(+) depletion during and after ischemia/hypoxia induced long-lasting membrane depolarization promotes neuronal apoptosis. Although it has been suggested as an important potassium channel subtype in oxidative stress induced neuron apoptosis, whether Kv2.1 mediates ischemic apoptosis remains undefined. In the present study, the role of Kv2.1 played in hypoxia/anoxia induced cell apoptosis and correlated protective effect of donepezil were evaluated. Kv2.1 transfected HEK293 cell line (Kv2.1/HEK293) was used to study oxygen-glucose deprivation (OGD) induced cell apoptosis. We found Kv2.1 transfection increased the vulnerability of HEK293 cells to OGD insult, blocking Kv2.1 potassium channel by tetraethylammonium (TEA, 10mM) could attenuated OGD induced Kv2.1/HEK293 cell apoptosis significantly. OGD slightly reduced Kv2.1 currents without affecting channel kinetic activity. However, the membrane potential of Kv2.1/HEK293 cells depolarized to around 0mV after OGD treatment, a potential which could activated Kv2.1 persistently. Donepezil blocked Kv2.1 currents in a dose-dependent manner (IC(50)=7.59μM). Under OGD condition, donepezil (30μM) effectively inhibited Kv2.1 currents by accelerating channel inactivation and decreased Kv2.1/HEK293 cell apoptosis rate. In conclusion, our study revealed both the conducting role of Kv2.1 in OGD induced cell apoptosis and the importance of Kv2.1 as a target for neuronal protection. In addition, besides anti-acetylcholinesterase activity, Kv2.1 blockade capability of donepezil may attribute to its neuroprotective effects against ischemic apoptosis.
authors.affiliation: Department of pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, No.1 Xiannongtan Street, Xuanwu District,Beijing 100050, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yuan
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Feng
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Xiao-Liang
authors.initials: XL
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015687:Cell Hypoxia; D000077265:Donepezil; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D055724:Electrophysiological Phenomena / Q000187:drug effects; D005947:Glucose / Q000172:deficiency*; D057809:HEK293 Cells; D006801:Humans; D007189:Indans / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D051669:Shab Potassium Channels / Q000037:antagonists & inhibitors* / Q000235:genetics; D014162:Transfection
chemical_list: D007189:Indans; D010880:Piperidines; D026902:Potassium Channel Blockers; D051669:Shab Potassium Channels; D000077265:Donepezil; D005947:Glucose; D010100:Oxygen