Fig. 10.

Cross-inhibition between P2X₃ or P2X₄ receptors and α₃β₄ nAChRs is maintained during receptor desensitization. A: histograms showing the amplitude of ACh (3 mM) and ATP (1 mM) currents before P2X₃ receptor desensitization. ATP was then applied continuously to desensitize the P2X₃ receptors, and ACh was reapplied in the continued presence of ATP (see Fig. 8 for protocol). The ACh current was significantly smaller than that recorded before P2X₃ receptor desensitization. B: histograms showing results of experiments similar to those in A but using cells coexpressing P2X₄ receptors and α₃β₄ nAChRs. The ACh current recorded during P2X₄ receptor desensitization was smaller than that recorded before the desensitization protocol. *Significantly different from current recorded before desensitization (P < 0.05) in both sets of experiments.