Fig. 2.

The characterization of IQ-induced responses in cultured DRG neurons. (A) Application of IQ (20 μg/mL) increased intracellular Ca²⁺ in DRG neurons. Each trace indicates responses of representative DRG neurons in calcium imaging assay. (B) Extracellular calcium was not required for IQ-induced Ca²⁺ responses in DRG neurons. (C) Effects of inhibitors in blocking IQ-induced Ca²⁺ responses. The cells were pretreated with U73122 (10 μM) or 2-APB (20 μM) for 3–5 min before the addition of IQ. For PTX (200 ng/ml), at least 4 h of preincubation preceded application of IQ. Note that pretreatment of 2-APB profoundly impaired IQ-induced Ca²⁺ responses [only 2.2% (14/633) cells responded]. The percentages are given as the number of IQ-responding neurons of total DRG neurons counted. Approximately 400–800 cells were studied in at least four separate experiments. Asterisks mark significant differences compared with control (P < 0.05, Student's t test, unpaired). Error bars represent SEM. (D) Patch-clamp recording: the treatment of IQ (20 μg/mL) generated a train of action potentials in DRG neurons.