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.

中文翻译：

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α-氯氰菊酯和θ-氯氰菊酯对大鼠海马神经元延迟整流钾电流的影响。

氯氰菊酯是一种光稳定的合成拟除虫菊酯，也是使用最广泛的II型拟除虫菊酯农药。使用全细胞膜片钳技术研究了氯氰菊酯杀虫剂的两种不同立体异构体α-氯氰菊酯和θ-氯氰菊酯对大鼠海马神经元延迟整流钾电流（IK）的影响。α-氯氰菊酯和theta-氯氰菊酯降低IK的振幅值，并在任何浓度（10（-9）M，10（-8）M，10（-7）M下将IK的稳态激活曲线移向负电位）。此外，在较高的浓度下，α-氯氰菊酯（10（-7）M）和θ-氯氰菊酯（10（-8）M，10（-7）M）具有可观察到的IK稳态失活作用。结果表明，IK是α-氯氰菊酯和θ-氯氰菊酯的靶标，这可能解释了氯氰菊酯的两种立体异构体对哺乳动物神经元毒性作用的机理。电压门控延迟整流器K +通道的氯氰菊酯改变的特性可能通过在海马CA3神经元中引起异常放电来促进神经毒性。