Objective: To determine the fiber type participating in the peripharal information transmission across nerve segments. Methods: Experiments were performed on SD rats anesthetized with intraperitoneal injection of 20% urethane 1 g/kg. The dorsal cutaneous branches of T 9 and T 10 spinal nerves innervating “Ganshu" (BL 18)

and “Danshu”(BL 19)of the Pangguang Meridian of Foot Taiyang were freed and cut proximally. The C fiber endings capable of responding to mechanical stimuli were obtained by isolating nerve filaments on the dorsal cutaneous branch of T 10 spinal nerve. Those filaments responding to hair brushing

von Frey's hair pressing were subjected into this study. The dorsal cutaneous nerve of T 9 was antidromically stimulated with single electric pulses. Firing signals were processed with sequential density histograms. Results: It was found that 87.5% (35/40) of the slow adapting units and 50%(5/10) of the fast adapting units of the C fiber endings fired more actively within the first 90 sec after the stimulation

particularly within the first 30 ecs (P<0.001). Slow adapting units and those having a longer after discharge were prone to be activated by electrical stimulation of the adjacent spinal segments. There was no correlation between the spontaneous discharge frequency of unit and its response to the stimulation. Conclusion: These results suggest that the C fibers participate in the information transmission across spinal segments between the peripheral endings

which may contribute to the phenomenon of the sensory conduction along channels.