摘要
为了观察大鼠背根节神经元对不同速率（ｄＩ／ｄｔ）去极化电流刺激的反应性，本实验采用全细胞膜片钳技术，在新鲜分散的后根节神经元胞体上，以持续去极化电流（４００ ｐＡ， １８０ ｍ ｓ）刺激所诱发的重复放电为指标，观察改变去极化速率对重复放电频率和幅度以及最大复极化电位的影响。结果发现：随着去极化速率的减小（２０、１０、６．６、５、４ ｐＡ／ｍ ｓ）重复放电频率逐渐增加。若与方波去极化电流刺激所诱发重复放电的频率和幅度（定为１００％ ）相比较，放电频率分别增加为１０９．４５±２．６％ （Ｐ＜ ０．０５），１１３．３±２．８（Ｐ＜ ０．０１），１１５．６±２．４（Ｐ＜ ０．０１），１２１．３±２．４（Ｐ＜ ０．００１）和１２２．８±３．１（Ｐ＜ ０．００１）；放电幅度分别减小到方波电流刺激时的９４．５±１．２（Ｐ＜ ０．００１），９２．８±２．７（Ｐ＜ ０．０１），８４．５±２．９（Ｐ＜ ０．０５），８２．８±１．９（Ｐ＜ ０．０５）和７５．０±４．５（Ｐ＜ ０．０１）；增加去极化电流的强度（４００， ６００ 和８００ ｐＡ），仍可观察到重复放电频率和幅度随去极化速率而变化的现象。但随着强度的增加。
The depolarizing current stimuli with differential velocity (dI/dt), sustained depolarizing current stimuli with intensity at 400 pA and duration at 180 ms were used to evoke repetitive firing of acutely dissociated DRG neurons. When the velocity of depolarizing current were decreased from 20 pA/ms to 4 pA/ms (20, 10, 6.6, 5 and 4 pA/ms), the repetitive firing frequency was increased and the amplitude was decreased respectively. Comparing with the frequency and amplitude (100%) induced by square wave depolarizing current stimulation, the firing frequency was increased to 109.45%±2.6%(P<0.05), 113.3±2.8%(P<0.01), 115.6±2.4%(P<0.01), 121.3±2.4%(P<0.001)and 122.8±3.1% (P<0.001) respectively, while the firing amplitude was decreased to 94.5%±1.2%(P<0.001), 92.8±2.7%(P<0.01), 84.5±2.9(P<0.05) and 75.0±4.5%(P<0.01). The above phenomena persisted when the depolarizing current intensity was increased to 600 pA or 800 pA, but the frequency and amplitude became smaller while the intensity of depolarizing current was increasing. The maximum repolarizing potential were decreasing gradually while the firing frequency was increasing. When the depolarizing voltage stimuli with decreasing velocity were applied to evoke the whole cell Ca 2+ , Na 2+ and K + current, the whole cell currents were decreased significantly. These data showed that the velocity of depolarizing current might be one of the components which regulates the frequency and amplitude of repetitive firing, and the permeability of Ca 2+ , Na 2+ and K + channels.
出处
《神经解剖学杂志》
CSCD
北大核心
1999年第4期325-331,共7页
Chinese Journal of Neuroanatomy
基金
国家自然科学基金!资助项目(No. 39670247)
关键词
去极化速率
背根节
重复放电
全细胞膜片钳
大鼠
Velocity of depolarizing current
dorsal root ganglion
repetitive firing
whole cell patch clamp
rat
