A cell model study of calcium influx mechanism regulated by calciumdependent potassium channels in Purkinje cell dendrites

被引:6
作者
Chono, K
Takagi, H
Koyama, S
Suzuki, H
Ito, E
机构
[1] Hokkaido Univ, Grad Sch Sci, Div Biol Sci, Kita Ku, Sapporo, Hokkaido 0600810, Japan
[2] Shinshu Univ, Sch Med, Dept Physiol 2, Matsumoto, Nagano 3908621, Japan
[3] Waseda Univ, Sch Sci & Engn, Dept Phys, Shinjuku Ku, Tokyo 1698555, Japan
[4] Hokkaido Univ, CRIS, Div Innovat Res, Kita Ku, Sapporo, Hokkaido 0600810, Japan
关键词
Ca2+ channel; dendrite; K+ channel; multi-compartment model; Purkinje cell; simulation; ELECTRO-PHYSIOLOGICAL PROPERTIES; HIPPOCAMPAL PYRAMIDAL NEURONS; MAMMALIAN CEREBELLAR SLICES; CA2+-ACTIVATED K+-CHANNEL; ACTIVE MEMBRANE MODEL; GATED CA2+ CHANNELS; SIGNAL-TRANSDUCTION; PERIPHERAL NEURONS; EPSP INTEGRATION; CLIMBING FIBER;
D O I
10.1016/S0165-0270(03)00194-8
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
The present study was designed to elucidate the roles of dendritic voltage-gated K+ channels in Ca2+ influx mechanism of a rat Purkinje cell using a computer simulation program. First, we improved the channel descriptions and the maximum conductance in the Purkinje cell model to mimic both the kinetics of ion channels and the Ca2+ spikes, which had failed in previous studies. Our cell model is, therefore, much more authentic than those in previous studies. Second, synaptic inputs that mimic stimulation of parallel fibers and induce sub-threshold excitability were simultaneously applied to the spiny dendrites. As a result, transient Ca2+ responses were observed in the stimulation points and they decreased with the faster decay rate in the cell model including high-threshold Ca2+-dependent K+ channels than in those excluding these channels. Third, when a single synaptic input was applied into a spiny dendrite, Ca2+-dependent K+ channels suppressed Ca2+ increases at stimulation and recording points. Finally, Ca2+-dependent K+ channels were also found to suppress the time to peak Ca2+ values in the recording points. These results suggest that the opening of Ca2+-dependent K+ channels by Ca2+ influx through voltage-gated Ca2+ channels hyperpolarizes the membrane potentials and deactivates these Ca2+ channels in a negative feedback manner, resulting in local, weak Ca2+ responses in spiny dendrites of Purkinje cells. (C) 2003 Elsevier B.V. All rights reserved.
引用
收藏
页码:115 / 127
页数:13
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