Fig. (1) Antidromic Electrical Stimulation (ES) of dorsal roots induced sensitization of peripheral C fibers. A. Representative traces showed the firing of a single fiber induced by von Frey filaments at baseline, 0, 5, 15 and 30 min after antidromic ES of dorsal roots. Upper panel: the real-time histogram showing the spike frequency of the fiber with von Frey stimulation. Lower panel: original firing traces from the fiber. B. Pooled data from 12 fibers of 12 rats showed antidromic ES-induced sensitization in firing of fibers to von Frey stimuli. Sensitization exhibited longer duration when the fibers were challenged with stronger intensity. *, p < 0.05; responses after ES vs. before ES with the stimulus intensity of 20 mN. #, p < 0.05 responses after ES vs before ES with the stimulus intensity of 36 mN.