Mechanical force evokes more action potentials in HbSS mice thaninHbAA control mice. (A) Examples of recordings from C fibers from HbSS and HbAA mice responding to increasing sustained force stimuli (100 mN, 150 mN, 200 mN; 10 seconds each). Action potential waveforms are shown on the right. Average number of action potentials evoked per second in C fibers (B; ***P < .0001; repeated measures 2-way ANOVA), all AM fibers (C; P > .05), high-threshold AM fibers (D; ***P < .001; repeated measures 2-way ANOVA), and low-threshold AM fibers (E; P > .05) by a 10-second, sustained mechanical force applied to the receptive field in increasing intensities (5 mN, 10 mN, 20 mN, 40 mN, 100 mN, 150 mN, 200 mN, and 245 mN for C-fibers only) in HbAA and HbSS mice. AM fibers with von Frey thresholds ≥ 4 mN were considered high-threshold and AM fibers with von Frey thresholds < 4 mN were considered low-threshold.