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蚕豆保卫细胞质膜上一种高通导性的阳离子通道

武维华

北京农业大学生物学院植物生理生化系. 北京 100094

摘要

全细胞记录表明蚕豆保卫细胞质膜上的高通导性的阳离子通道为钾离子通道。在膜电位为-180mV时, 通过具有高通导性阳离子通道的保卫细胞整个质膜的内向钾电流约为1.5-2.5nA, 而通过一般保卫细胞整个质膜的内向钾电流约为0.3-0.5nA。单离子通道记录显示, 一些分离膜片上存在有高通导性的内向阳离子通道。当膜电位为-118mV时, 该内 向阳离子通道的通导性约为一般内向钾离子通道通导性的5倍。这些具高通导性阳离子通道的特殊保卫细胞的存在可能与逆境条件下气孔的快速效应机制有关。

关键词： 蚕豆; 气孔; 保卫细胞; 质膜; 钾离子通道; 膜片钳

A novel cation channel in Vicia faba guard-cell plasma membrane

Wu Weihua

Department of Plant Physiology and Biochemistry, College of Biological Sciences. Beijing Agricultural University. Beijing 100094

Abstract

Patch clamp technique was used to study K+ channels in Vicia faba guard-cell plasma membrane. Novel cation channels with high conductance were observed and recorded at both whole-cell and single-channel levels in some guard cell protoplasts. The channels were identified as K+ channels at whole-cell level by the reversal potential of tail currents. Whole-cell inward K+ currents at -180mV were between 1.5 and 2.5nA per cell in those guard-cell protoplasts with high membrane conductance, while inward K+ currents at -180mV were only 0.3-0.5nA per cell in most of the calmped guard-cell protoplasts used for experiments. The normalized whole-cell inward K+ currents (pA/pF) at -180 mV were 0.3 to 0.3nA per cell for those guard cells was 5 to 8 times higher than that from the most of guard cells. Single-channel recordings in some membranc patches also showed cation channel activity with unusually high conductance. Single channel conductance of these novel cation channels was approximately 5 times of that of the normal K+ channels in most membrane patches and of the previously repored inward K+ channels in the plasma membrane of Vicia faba guard cells. It is concluded that there are cation channels with high conductance in some guared guard cells, which may provide physiological mechanisms for rapid response of stomata to environmental stresses.

Key words: Vicia faba;Stomata;Guard cell;Plasma membrane;K~(+) channel;Patch clamp

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引用本文：

武维华. 蚕豆保卫细胞质膜上一种高通导性的阳离子通道[J]. 生理学报 1995; 47 (4): .

Wu Weihua. A novel cation channel in Vicia faba guard-cell plasma membrane. Acta Physiol Sin 1995; 47 (4): (in Chinese with English abstract).