HC-030031 inhibits mechanically-evoked firing in C fiber nociceptors. A) Example of C fibers from rat responding to increasing sustained force (40 mN, 100 mN, 150 mN; 10 sec each) after a 10 min incubation of the receptive field with either vehicle (1% DMSO; top; conduction velocity: 0.632 m/s; von Frey threshold: 11.7 mN) or HC-030031 (100 μM; bottom; conduction velocity: 0.394; von Frey threshold: 20.1 mN). Action potential waveform is shown at the right of each trace. B) Average number of action potentials evoked per second in C fibers by a 10 sec, sustained mechanical force applied to the receptive field in increasing intensities (5 mN, 10 mN, 20 mN, 40 mN, 100 mN, 150 mN) in the presence of vehicle (solid squares) or HC-030031 (100 μM; open circles). Y-axis bars represent the SEM for each mean data point. HC-030031 significantly reduced the mechanically-evoked firing across all force intensities (p = 0.0029; 2-way repeated measures ANOVA). C) Adaptation rate of action potential firing during a 10 sec, 100 mN mechanical force in the presence of vehicle (black bars) or HC-030031 (100 μM; grey bars). HC-030031 significantly inhibited the firing rate after the first second (p = 0.0052; 2-way ANOVA).