Fig. 1.

Ethanol concentration–response curves for position 46 mutant P2X4Rs. (a) Concentrations in the range of 10–200 mM were used. There were no significant differences among the mutants with respect to sensitivity to low ethanol concentrations (10, 25, and 50 mM) compared to WT P2X4R. However, at 100 and 200 mM ethanol, all mutations, with the exception of the aromatic residues (Y, F), significantly altered the response to ethanol (P < 0.05 compared to ethanol effects in the WT P2X4R). Data are expressed as mean + SEM, n = 6–28. The curve for WT is shown as an interrupted line. Boxes represent groups of receptors with similar ethanol responses. The following ATP EC₁₀ values (in μM) were used for studies in Figs. 2–4: WT 0.9, Tyr 0.9, Phe 0.8, Asp 0.15, Lys 0.25, Asn 0.15, Leu 0.25, Val 0.30, and Ala 0.30. (b) Representative tracings of ATP-induced currents in the absence and presence of 100 mM ethanol for WT, W46N, and W46A mutant P2X4Rs. ATP EC₁₀ for each receptor was used