Figure 5. ATP block of K_ATP channels in inside-out patches.

Recordings were made in control solutions (A and C) and 3 min after ATP application (B and D). The holding potentials are indicated near each trace in A. Dotted lines show closed (C) and first open levels (O₁). C and D, I-V relationships for the same patch obtained using a ramp protocol. The recording pipette contained 133 mM KCl and 1.5 mM Ca²⁺. The straight line corresponds to a channel conductance (γ) of 50 pS. Note that the channel current deviates from the straight line at positive potentials, indicating inward rectification.