Table 1.

Ratio of second/first ATP‐induced Ca²⁺ peak (2^nd/1^st fura‐2 peak) (Fig. 1 C) in cells expressing wild‐type or indicated mutants of P2X₄

P2X4 mutant	2nd/1st fura‐2 peak	N	P value
Wild‐type	0.57 ± 0.06	102
H140D	0.34 ± 0.09	25	0.11
H140A	0.40 ± 0.06	40	0.22
H140R	0.31 ± 0.07	34	0.02
H241D	0.38 ± 0.06	55	0.05
H241A	0.34 ± 0.05	57	0.01
H241R	0.25 ± 0.07	30	0.004
H286D	0.45 ± 0.10	25	0.76
H286A	0.20 ± 0.03	65	<0,0001
H286R	0.05 ± 0.02	36	<0,0001

Cells were primed by a brief (1 min) perfusion with acidic (pH 5) solutuion before the second ATP application. P values are derived from ANOVA.