细胞膜单通道非平衡态离子动力学研究

北京大学学报（自然科学版）

细胞膜单通道非平衡态离子动力学研究

陈健

生物膜和膜生物工程国家重点联合开放实验室, 北京大学生命科学学院, 北京，100871

收稿日期:1994-01-11 出版日期:1995-01-20 发布日期:1995-01-20

Non-Equilibrium Ion Kinetics Study of Single IonChannel In Cell Membrane

CHEN Jian

National Laboratory of Biomembrane and membrane Technology, College of Life Sciences, Peking University, Beijing, 100871

Received:1994-01-11 Online:1995-01-20 Published:1995-01-20

摘要/Abstract

摘要： 速率学说更合理地解释离子通过离子通道中孔道的过程。本文将速率学说建立在Markor过程理论基础上，得到非平衡定态时越过能垒的离子流和膜钳制电位之间关系的一般模型。并将系统辨识中的单纯形法引入非平衡定态模型中的参数估计。采用膜片钳制技术记录了离体培养的新生大鼠大脑皮质神经元钾离子单通道电流。在膜两侧对称高钾溶液下，通道电流和电压之间呈线性关系的范围为：细胞贴附模式下，±60mv，内膜向外时±40mv。在此范围之外，通道电流和电压之间呈非线性关系。能垒分布接近三能垒模型。细胞贴附时膜外侧能垒最高，中间能垒最低，这种分布导致通道电流和电压之间的S型关系。内膜向外模式下，从膜内到膜外，能垒高度依次递增。孔道内能垒不对称是导致通道电流整流现象的基础。

关键词: 膜片钳, 速率理论, 能垒模型, 大脑皮层神经元, 钾离子单通道

Abstract: Setting the RateTheory on the basis of Markov process, the paper proposed a model concerning the relation between the membrane holding potential and the non-equilibrium stable ion flow passing through various barriers. The parameters of the model could been estimated by the Simple Search Method. The single potassium current of cultured cerebral neuron of newborn rat was recorded by patch clamp technique. The channel current was linearly related with holding potential ±60mv in cell-attached mode and ±40mv in inside-out mode, but was nonlinear at higher potential. The experimental results could been fitted by three barrier model. The energy barrier distribution, highest at extra-side of the pore and lowest at the middel, caused the Sshape IV relation in cell-attached mode. The energy barrieres decreased from extra-side to inner-side in inside-out mode. The rectification could be resulted from asymmetrical energy distribution in the pore of ion channel.

Key words: patch clamp, rate theory, energy-barrier model, cerebral neuron, single patassium channel

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