Figure 4

Substance P sensitivity is more prevalent in large neurons. All cells were tested for sensitivity to Substance P after testing for expression of currents elicited by pH7, capsaicin and ATP. ATP currents were classified as P2X3 based on their kinetics of activation and deactivation. The fraction of small (blue), medium (red), or large (green) cells for each group was determined for all cells, all Substance P sensitive cells (SP Sens), cells that were excited by Substance P (SP Sens ↑), cells that were inhibited by Substance P (SP Sens ↓), all cells that expressed ASIC channels (pH 7 Sens), all cells that expressed capsaicin receptors (CAPS), and all cells that expressed P2X3-like ATP currents (P2X3). Bars marked with the symbol * show groups whose size distribution is statistically different from all cells outside that population (p < 0.05, Fisher’s exact test).