氯胺酮对离体海马神经元的浓度相关性作用  

Concentration-dependent Actions of Ketamine on CA1 Pyramidal Neurons of Rat Hippocampus in Vitro

作　　者：蒋娟[1] 汪萌芽[1] 胡凤玉 潘群皖[1] 

机构地区：[1]皖南医学院细胞电生理研究室

出　　处：《皖南医学院学报》2002年第4期244-246,共3页Journal of Wannan Medical College

基　　金：安徽省自然科学基金 (编号 0 0 0 44 5 2 4);院中青年科研基金 (编号WK2 0 0 0 112 0 0 10 1)资助

摘　　要：目的　了解氯胺酮对海马神经元的作用以分析其“分离麻醉”的机制。方法　采用常规细胞内记录技术 ,观察不同浓度的氯胺酮对成年大鼠海马CA1区锥体神经元的影响。结果　给予 0 .3、1及 3mmol/L的氯胺酮灌流 15min(n =16 ) ,能浓度依赖地增大细胞的输入斜率电阻、延长时间常数 (P <0 .0 5 ) ,但是 3mmol/L氯胺酮还降低了直接动作电位的幅度 (P <0 .0 5 )。氯胺酮对I F曲线及阈电位的影响显示 (n =12 ) :0 .3和 1mmol/L的氯胺酮分别使 2 5 %的细胞升高了内在兴奋性 ,而 1mmol/L还使 75 %的细胞降低了兴奋性 ,3mmol/L则降低了所有记录细胞的兴奋性。刺激Schaffer侧支在CA1锥体细胞诱发的兴奋性突触后电位 ,当灌流 0 .3mmol/L氯胺酮时有 80 %的细胞被增强 ;1mmol/L时有 91%的细胞出现先增强后抑制的作用 ,但在 3mmol/L时在所有的细胞反应被完全取消。结论　氯胺酮对海马CA1区锥体神经元具有低浓度兴奋而高浓度抑制的双向作用 。Objective\ To analyze the mechanism of dissociative anesthetic action by ketamine. Methods\ The conventional intracellular recording techniques in adult rat hippocampal slices were used to test actions of ketamine at varied concentration on CA1 pyramidal neurons. Results\ Superfusion of ketamine 0.3, 1 and 3 mmol/L for 15 min were given in 16 neurons. In 9 cells tested, ketamine concentration dependently increased input slope resistance and time constant(F test, P<0.05). The amplitude of direct action potential was only decreased by ketamine 3 mmol/L (P<0.05). From I F curve and threshold value, it was found that intrinsic excitability of cells was increased by ketamine 0.3 and 1 mmol/L in 25% of cells tested, but decreased by 1 and 3 mmol/L in 75% and 100% cells, respectively. The excitatory postsynaptic potentials evoked by stimulation of Schaffer collaterals were potentiated by ketamine at 0.3 mmol/L in 80% cells, but enhanced first and then inhibited at 1 mmol/L in 91%, finally nullified at 3 mmol/L in 100%. Conclusion\ These results suggest that ketamine may present distinct actions on CA1 pyramidal neurons at varied concentration by different mechanisms.

关 键 词：氯胺酮 谷氨酸 海马 膜电位 电生理学 

分 类 号：R332[医药卫生—人体生理学] R322.81[医药卫生—基础医学]