Fig. 5.

The influence of hypoxia and low pH on bradykinin-stimulated response (from 0 second to 100 seconds) in ND7/23 soma. (A-D) First derivative of the normalized fluorescence (ratio of F-F₀ and F₀), which indicates intracellular calcium concentration fluctuation. Each colored curve represents one soma from each cell. Peaks in the curve are regarded as calcium events which indicate neuronal discharge. Around 120 to 450 cells per group were included for this study. (E) Proportion of cells with calcium events. The definition of calcium event is the peak in the derivative curve larger than 0.05/sec. Chi-square method was used for statistics. (F-H) Maximum fluorescent elevation speed, peak frequency, and peak height were calculated based on the derivative curve. Blue spots in the plots show data distribution; black bar represents median; error bars in panels F and H show 95% confident interval of median (calculated using bootstrapping method); while error bar in panel G shows 25% and 75% quantile. A p-value was calculated using pairwise comparisons of Wilcoxon rank sum test. A value of p<0.05 was regarded as significant and those values were shown in the plots. (I-L) Examples of images before (baseline) and at 0.5 μM bradykinin stimulation in the calcium imaging time-lapse sequence. Arrows in panel K indicate soma calcium response, while arrow heads in panel K indicate outgrowth calcium signal responding to bradykinin. Scale bars equal to 100 μm. DRG, dorsal root ganglion.