Figure 3
Total I Na currents in large sensory neurons following exposure to CFA. (A) Whole-cell voltage-clamp current traces of INa are recorded from sham and CFA large-soma DRG neurons. Total currents were elicited by a series of 500-ms test pulses ranging from –80 to +40 mV in 5 mV steps. (B) I-V curves of total INa currents obtained from large-soma rat DRG neurons (Capacitance >70 pF). Maximum peak currents are observed at –25 mV in all groups with the exception of day 8 post-inflammation (–30 mV). (C) Histogram showing that the development of chronic inflammation induced by CFA intraplantar injection (days 3, 8, and 14 post-CFA) increases total INa peak currents. Data shown as mean ± SEM (*P <0.05, ***P <0.001 vs. sham; $ P <0.05 vs. day 8; ANOVA followed by Sidak’s MCT; n = 8–11). (D) Voltage-dependent activation of total INa currents in large sensory neurons from inflamed rats. At day 8, CFA shifts the activation curve in a hyperpolarizing direction (V1/2act = –39.7 ± 1.6 mV for inflamed rats vs. –32.7 ± 0.8 mV for sham group; **P <0.01). Half-activation and half-inactivation potentials and slope factors are summarized in Additional file 2: Table S2.