title: Effect of alpha-cypermethrin and theta-cypermethrin on delayed rectifier potassium currents in rat hippocampal neurons.
abstract: Cypermethrin is a photostable synthetic pyrethroid and the most widely used Type II pyrethroid pesticide. The effects of two different stereoisomers of cypermethrin insecticides, alpha-cypermethrin and theta-cypermethrin, on the delayed rectifier potassium current (IK) in hippocampal neurons of rat, were studied using whole-cell patch clamp technique. Alpha-cypermethrin and theta-cypermethrin decreased the amplitude value of IK, and shifted the steady state activation curve of IK towards negative potential at any concentrations (10(-9) M, 10(-8) M, 10(-7) M). Furthermore, at higher concentration, alpha-cypermethrin (10(-7) M) and theta-cypermethrin (10(-8) M, 10(-7) M) had observable effects of the steady state inactivation of IK. The results suggest that IK is the target of alpha-cypermethrin and theta-cypermethrin, which may explain the mechanism of toxic effects of both steroeisomers of cypermethrin on mammalian neurons. Cypermethrin-altered properties of voltage gated delayed rectifier K+ channels may contribute to neurotoxicity by eliciting abnormal electrical discharges in hippocampal CA3 neurons.
authors.affiliation: Key Lab. of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China.
authors.forename: Yu-Tao
authors.initials: YT
authors.lastname: Tian
authors.forename: Zhao-Wei
authors.initials: ZW
authors.lastname: Liu
authors.forename: Yang
authors.initials: Y
authors.lastname: Yao
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Yang
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
mesh_terms: D000818:Animals; D051668:Delayed Rectifier Potassium Channels / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D011722:Pyrethrins / Q000737:chemistry* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D051668:Delayed Rectifier Potassium Channels; D011722:Pyrethrins; C017160:cypermethrin