Figure 4. P2X7 and P2X4 receptors are both expressed on epiplexus cells, but only P2X4 is involved in chemokinesis. (A) Immunofluorescent staining for P2X4 receptors in epiplexus cells and CP epithelium. Note that both the epithelial and the epiplexus cells are positive for P2X4. (B) Immunofluorescent staining for P2X7 receptors is evident only in epiplexus cells. (C, D, and E) The P2X7 receptor blocker 1 µM BBG did not prevent activation of epiplexus cell by ATP, and the P2X7 receptor agonist BzATP did not trigger an increase in epiplexus cell activity. Thirty µM 5-BDBD, a P2X4 receptor antagonist, alone or in combination with probenecid significantly decreased ATP-triggered chemokinesis. (C) Normalized average distance and statistical analysis where each symbol represents an individual cell; (D) normalized summative distance; (E) slope of normalized summative distance where each symbol represents the average of all cells in a given CP. Scale bars are 50 μm.