Figure 1. NaOCl induces Ca²⁺ influx and ionic currents in mustard oil–responsive sensory neurons.

(A) Activation of Ca²⁺ influx into cultured murine DRG, nodose (ND), and trigeminal (TG) neurons by NaOCl, as measured by fluorescent Fura-2 imaging, before and 70 s after challenge with NaOCl (24 ppm), followed by 100 μM mustard oil (MO) after 40 s. Pseudocolors denote 0–3 μM [Ca²⁺]_i. Original magnification, ×10. (B) [Ca²⁺]_i concentration of DRG neurons activated by application of NaOCl followed by mustard oil, capsaicin (Cap), and 65 mM KCl. Thick and thin lines denote mean and ± SEM, respectively. Neurons (n = 300) were analyzed from 4 mice at ×10 magnification. (C) Kinetics of OCl^–-activated cationic currents and ruthenium red–induced block in cultured murine DRG neurons. NaOCl was superfused after 20 s; after 60 s, ruthenium red (RuRed) was added to the NaOCl. Currents were measured using a ±80 mV voltage ramp protocol over 100 ms at 0.5-Hz intervals (0 mV holding potential throughout). Black and gray lines denote mean and ± SEM, respectively, of currents from 6 neurons at –80 and +80 mV plotted versus time. Intracellular Cs-based solution contained 10 mM EGTA. (D) Representative current-voltage relationship of a OCl^–-sensitive DRG neuron before application of NaOCl (black), during maximal activation by NaOCl (24 ppm, green), and after application of 10 μM ruthenium red (red). Residual voltage gated currents observed are caused by incomplete inactivation of voltage-gated channels. Currents were measured as in C.