FIGURE 7.

ATP⁴⁻-dependence of P2X₇ channel gating. (A) Dependence of single channel current amplitude of short (<9 ms, solid circles) and long (>9 ms, open circles) channel openings. Means for both gating modes are significantly different, but independent of [ATP⁴⁻]. (B) Open probability calculated from amplitude histograms. Data were fitted by Eq. 4. P_o([ATP⁴⁻]) of the short openings as calculated by the C-C-C-O model (see Fig. 9 C) is depicted as a dotted line. (C, D) Mean open and closed time components measured as shown in Fig. 4. All mean open time components and the short mean closed times (τ_c,0) were independent of [ATP⁴⁻]. The open and closed times predicted by the model are drawn as dotted and dashed lines as depicted in the inset. N = 3–18 patches from 3 to 13 different oocytes, K⁺ pipette solution, V_h = −120 mV.