大鼠海马CA1区锥体细胞上一种Ca^(2+)依赖性K_(ATP)通道  

Ca^(2+)-dependent K_(ATP) Channel, a New Subtype of K_(ATP) Channel in Hippocampal CA1 Pyramidal Neurons From Adult Rat

作　　者：周英杰[1] 佟振清[1] 高天明[1] 

机构地区：[1]第一军医大学生理教研室,广州510515

出　　处：《生物化学与生物物理进展》2002年第1期78-82,共5页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金(39970 2 65);广东省自然科学基金 (990 395);军队杰出人才基金 (0 1J0 0 9)资助项目~~

摘　　要：KATP通道在细胞的新陈代谢与膜兴奋性的耦联中起重要作用 .采用膜片钳的内面向外式记录方法 ,在成年大鼠海马CA1区锥体细胞上记录到一种被胞浆侧ATP和甲糖宁 (tolbutamide,一种KATP通道阻断剂 )抑制的Ca2 + 依赖性钾离子通道 .在细胞膜内外的K+ 浓度均为 140mmol/L时 ,通道的电导为 (2 0 4± 2 1) pS ,翻转电位为 (3 5 7± 1 13)mV ,通道无整流性 .通道开放概率及ATP对通道的抑制作用均呈现电压依赖性 .该KATP通道与以往报道的“经典”KATP通道有显著不同 ,其活动受膜电位、胞内Ca2 + 和ATP三重调节 ,表明这是一种新型的KATP通道 .上述结果表明在海马神经元上至少有两种性质不同的KATP通道 ,提示神经元可能通过不同性质的KATP通道感受细胞内的代谢状态 ,进而调节细胞膜的兴奋性 .ATP-sensitive K+ channels play an important role in coupling membrane excitability with intracellular metabolic stress. To characterize such K-ATP channels from rat brain, the inside-out mode of patch-clamp technique was applied to freshly dissociated hippocampal CA1 pyramidal neurons of adult rat. One type of K+ permeable channel was recorded only at the presence of Ca2+ in the internal solution and it could be inhibited by application of 1 similar to 3 mmol/L ATP and 1 mmol/L tolbutimade, a K-ATP channel blocker. Both of channel open probability and the ATP induced-inhibition displayed a voltage-dependent fashion. When both sides of the excised membrane were in symmetrical 140 mmol/L K+, the I-V relation was linear with a conductance of 204 pS and reversal potential was 3.57 mV. Unlike the previously reported 'classical' K-ATP channel, this large-conductance K-ATP channel ( L-K-ATP) was regulated by membrane potential, intracellular Ca2+ and ATP, indicating a new subtype of K-ATP channel presents in hippocampus neurons. These results demonstrate that at least two distinct K-ATP channels exist in rat hippocampal neurons and suggest that metabolic state may be continuously sensed in neurons via different K-ATP channels with resulting alterations in neuronal membrane excitability.

关 键 词：ATP敏感钾通道 CA^2+ 海马 CA1区 膜片钳 大鼠 

分 类 号：Q424[生物学—神经生物学] R338.8[生物学—生理学]