Fig. 6.

ACh and ATP do not directly modulate P2X₂ receptor or α₃β₄ nAChR function. A: ATP (1 mM) caused an inward current in a HEK-293 cell stably expressing only the P2X₂ receptor. ACh (3 mM) did not cause an inward current in these cells. ATP and ACh coapplication caused an inward current that did not differ from the response caused by ATP alone. B: pooled data from experiments shown in A. In cells expressing only the P2X₂ receptor, coapplication of ATP and ACh caused an inward current that is not different from the response caused by application of ATP alone (P > 0.05). C: ACh (3 mM) caused an inward current in a HEK-293 cell stably expressing only the α₃β₄ nAChR. ATP (1 mM) did not cause an inward current in these cells. ATP and ACh coapplication caused an inward current that did not differ from the response caused by ACh alone. D: pooled data from experiments shown in C. In cells expressing only the α₃β₄ nAChR, coapplication of ATP and ACh caused an inward current that was not different from the response caused by application of ACh alone (P > 0.05).