Fig. 5.
Effect of capsaicin treatment on heat sensitivity of afferent units one day after plantar incision. A: Representative recording traces showing heat response of C-fibers. Capsaicin treatment decreased heat-responsiveness of C-fibers compared to vehicle infiltration. The upper, middle and lower panels show the spike density histograms (bin width = 1 s), digitized oscilloscope tracings and the heat stimuli applied, respectively. Insets display single action potential. CV = conduction velocity. B: Prevalence of heat-responsive fibers in C- and Aδ-fibers. *P < 0.001 vs. vehicle by χ2 test. C: Distribution of the receptive fields of C- and Aδ-fibers with or without heat sensitivity, for capsaicin- and vehicle-treated rats. Solid circles represent receptive fields of heat-responsive afferent units, and open circles represent those of non-responsive units.