根据文献报道电针脊髓具有明确的镇痛效果

并观察到电针对脊髓背角神经元有抑制效应

临床资料证明夹脊穴治疗某些疾病解除疼痛有良好疗效

我们过去的实验观察

发现脊椎旁电针刺激具有镇痛效应

这些资料均指示针刺镇痛过程中

脊髓起一定作用。考虑到在脊髓表面或脊椎旁外加电刺激时

是否首先引起脊髓的功能状态发生了某种变化

从而表现出对伤害性刺激的反应减弱的现象

同时考虑到实验研究中常采用脊髓反射放电作The present work is an investigation of the effect of para-vertebral electro-acupuncture on reflex discharges of the spinal cord in toads para- lyzed with Tubocurarini chlorid. The electric stimulation of a single rectangular pulse (wave width 1 millisecond

intensity 2～4 volts) or a brief train of rectangular pulses (rect. wave width 1 millisecond; frequency 20 cycles/sec; intensity 2～4 volts; duration of the train 500 milliseconds) were applied to the central end of the spinal dorsal root of the last spinal segment. The reflex discha- rges of the ipsilateral ventral root of the same segment were also recorded. Two needles were inserted vertically about 2～3 mm deep and symmetrically on both sides of the spine at the level between the third and fourth spinal vertebrae for electric stimulation. The parameters of needling stimulation were as follows: continuous bipolar pulses

frequency 60 cycles/sec

inte- nsity 2.5～4 volts

duration 2 minutes. The reflex potentials before and after electro-acupuncture were observed. One hundred and thirteen experiments were performed on 25 toads. The following results have been obtained. Both the poly-synaptic reflex discharges elicited by single rectangular pulse stimulation and a burst of reflex discharges by a brief train of re- ctangular pulse stimulation showed obvious changes under electro-acupu- ncture. Eighty-three (73.45 %) out of 113 experiments manifested inhibitory effect; eleven (9.73%) strengthened; seven (6.2%) temporarily strengthened and followed by inhibitiont and twelve (10.62%) no effect. The above observations indicated that the effect of paravertebral electro-acupuncture on spinal cord activities showed inhibition primarily

which might be responsible for the analgesia of para-vertebral electro- acupuncture. However

the mechanism of this inhibitory effect deserves further study.