Figure 6.

ATP activation of I_H. (A) Continuous current recording from a patch at V_h = −80 mV, with NMG⁺_o (pH 6) in the pipette, to which increasing [ATP] were added in the presence of 20 mM Na⁺_i. (B) Average I_H-V from six patches at different [ATP], normalized to I_H at −140 mV with 4 mM ATP. (C) [ATP] dependence of I_H activation in Na⁺_i at −140 mV. The solid line is the fit obtained using a rectangular hyperbola (Eq. 1, n_H = 1) with K_0.5ATP = 55.8 μM. The dotted line is the fit from Fig. 5D. To see this figure in color, go online.