Figure 4.

High affinity tolbutamide sensitivity depends on open-state stability. (A) Representative currents recorded from inside-out membrane patches containing wild-type or mutant K_ATP channels at −50 mV in K_int solution. Patches were exposed to differing [tolbutamide] or 5 mM ATP, as shown. (B) Current recorded from representative patch containing Kir6.2 [R176A]+SUR1 channels at −50 mV in K_int solution. The patch was exposed to differing [tolbutamide], ATP, or 5 μg/ml PIP₂, as shown. The dashed lines represent 12- and 2-min gaps.