Fig. 3

Effect of the local application of capsaicin on CBPN on the inhibition of RMCs by the electrical stimulation of CBPN. Representative results. A, B Before capsaicin treatment. C, D One hour after application of capsaicin. A, C Sample recordings of RMCs. Horizontal heavy bars indicate the stimulation time. B, D Compound action potentials of CBPN, averaged (600 times) during the stimulation with 10 V at 10 Hz for 1 min. The latency of the C fiber volleys in D is faster than in B probably because the nerve length may be shortened after capsaicin treatment for some reason, e.g., by movement of the stimulating or recording electrodes, or by movement of the nerve on the electrodes. The sharp waves with latencies of 2.5 ms (B and D) are Aδ-fiber volleys. The magnitude of that in D is smaller than that in B because there are capsaicin sensitive Aδ fibers [23, 29]