We performed experiments on sural nerves of the cats and rabitts to observe the effects of high frequency electrical stimulation on the functions of A

A

and C fibrils. The results show that neurostimulation reduces the conduction velocity

the amplitude and the ascending rate of active potentials in these nerve fibrils

prolongs refractory period

raises the threshold for their excitation

eventually leading to acomplete inhibition. After stimulation is stopped all functions of these nerve fibrils recover by degrees. Among these

inhibitory effects of C fibrils requires stimulation with greater intensity and longer period of time. These inhibitory effects reduce with the distance from high frequency stimulated sites. An alteration in C. N. S. activity does not influence these inhibitory effects. These results demonstrate that local blockade of peripheral nerves by high frequency electrical stimulation may be clinical analgesia mechanism by paraincision acupunctures.