Niven Jeremy E, Vähäsöyrinki Mikko, Juusola Mikko, French Andrew S
Physiological Laboratory, University of Cambridge, Cambridge CB2 1TN, United Kingdom.
J Neurophysiol. 2004 Jun;91(6):2696-706. doi: 10.1152/jn.01163.2003. Epub 2004 Jan 28.
Voltage-gated K(+) channels are important in neuronal signaling, but little is known of their interactions with receptor currents or their behavior during natural stimulation. We used nonparametric and parametric nonlinear modeling of experimental responses, combined with Hodgkin-Huxley style simulation, to examine the roles of K(+) channels in forming the responses of wild-type (WT) and Shaker mutant (Sh(14)) Drosophila photoreceptors to naturalistic stimulus sequences. Naturalistic stimuli gave results different from those of similar experiments with white noise stimuli. Sh(14) responses were larger and faster than WT. Simulation indicated that, in addition to eliminating the Shaker current, the mutation changed the current flowing through light-dependent channels [light-induced current (LIC)] and increased the delayed rectifier current. Part of the change in LIC could be attributed to direct feedback from the voltage-sensitive ion channels to the light-sensitive channels by the membrane potential. However, we argue that other changes occur in the light detecting machinery of Sh(14) mutants, possibly during photoreceptor development.
电压门控钾离子通道在神经元信号传导中很重要，但人们对它们与受体电流的相互作用或在自然刺激过程中的行为知之甚少。我们使用实验响应的非参数和参数非线性建模，并结合霍奇金-赫胥黎风格的模拟，来研究钾离子通道在形成野生型（WT）和摇蚊突变体（Sh(14)）果蝇光感受器对自然刺激序列的响应中的作用。自然刺激产生的结果与类似的白噪声刺激实验不同。Sh(14)的响应比WT更大且更快。模拟表明，除了消除摇蚊电流外，该突变还改变了流经光依赖性通道的电流[光诱导电流（LIC）]并增加了延迟整流电流。LIC的部分变化可归因于电压敏感离子通道通过膜电位对光敏感通道的直接反馈。然而，我们认为Sh(14)突变体的光检测机制中还发生了其他变化，可能发生在光感受器发育过程中。
