咪达唑仑对交感神经元电压门控性钾电流的影响  

Effects of midazolam on macroscopic voltage-gated potassium currents in rat sympathetic neurons

作　　者：茆庆洪[1] 庄心良[1] 陈猛[1] 唐俊[1] 徐国辉[1] 

机构地区：[1]上海市第一人民医院麻醉科,上海200080

出　　处：《中国临床药理学与治疗学》2002年第3期197-199,共3页Chinese Journal of Clinical Pharmacology and Therapeutics

摘　　要：目的 :观察不同浓度咪达唑仑对交感神经元电压门控钾通道电流的影响 ,探讨临床浓度咪达唑仑对钾电流的作用是否与抑制交感神经系统有关。方法 :用酶消化法获得急性分离的SD大鼠 (7～1 0d)颈上交感神经节细胞 ,应用膜片钳技术记录不同浓度的咪达唑仑对电压门控钾电流的影响。结果 :在钳制电位 (Vh) -80mV ,刺激电压 (Vt) -1 0 0mV～ 3 0mV ,时程 1 60ms条件下 ,不同浓度的咪达唑仑对电压门控钾电流均有抑制作用 ,且呈浓度依赖性。临床相关浓度的咪达唑仑(0 .3 μmol·L-1)使钾通道电流峰值下降3 .89% (P =0 .88)。5 0 %钾通道电流峰值受抑制时的咪达唑仑浓度(IC50 )约为 70 .0 6μmol·L-1。结论 :咪达唑仑对交感神经元电压门控钾电流具浓度依赖性抑制作用 ,但临床浓度咪达唑仑对钾电流影响较小。AIM: To explore the influence of different concentration midazolam on the macroscopic voltage gated potassium currents and to discuss the relationship between potassium currents and inhibitory effect of clinical relevant concentration midazolam on sympathetic nervous system. METHODS: Superior sympathetic ganglion neurons were dissociated enzymatically from 7 to10 day old rat. Experiments were performed about 5 h after plating at room temperature (20- 24 ℃ ). Appropriate solution was chosen to separate the K + current from the other transmembrane currents. 1 μmol·L -1 TTX was applied to the extracelluar solution to block the Na + current. Midazolam was also resolved in extracelluar solution to get various concentration ( 0.1 , 0.3 ,3,10,50,100 μmol·L -1 ). Currents were recorded with the patch clamp technique in whole cell configuration using glass electrodes with a tip resistance of 2- 4 M . Potassium currents were evoked by test pulse from -100 mV to +30 mV with holding potential -80mV. Data were analyzed using Clampfit 6.0 and Oringih 5.0 software. Whole cell current records were corrected for leakage and capacitance by using the P/5 protocol. RESULTS: Midazolam dose dependently inhibited the whole cell potassium currents. Clinical relevant concentration midazolam ( 0.3 μmol·L -1 ) only reduced the peak currents by 3.89 %(P= 0.88 ). The concentration required to produce 50% current inhibition(IC 50 ) was 76.065 μmol·L -1 . CONCLUSION: Midazolam inhibits the whole cell potassium current significantly and dose dependently, but clinical relevant concentration midazolam has minor effect on the potassium currents, indicating that the inhibitory effect of midazolam on potassium current is not related to the suppression of activity of sympathetic system.

关 键 词：咪达唑仑 交感神经节 电压门控性钾通道 膜片钳技术 电生理学 

分 类 号：R965[医药卫生—药理学]