FIGURE 9.

Effects of glibenclamide on the ADP and AMP sensitivity of wild-type Kir6.2 + SUR1. The left and right sides of the figure show that glibenclamide induces an increase in sensitivity of wild-type Kir6.2+SUR1 to both ADP and AMP, respectively. (A) Inward currents were suppressed by increasing concentrations of ADP, with the IC₅₀ near 1 mM. Glibenclamide (200 nM) was then added after removal of ATP. (B) After glibenclamide, the ADP sensitivity increased, with the IC₅₀ near 100 μM. (C) Plot of channel ADP sensitivity for Kir6.2+SUR1 before (•) and after (▾) glibenclamide. In this case, fit of the data points yielded k = 850 μM before glibenclamide (n = 5) and k = 105 μM after glibenclamide for (▾) (n = 5). (D) Inward currents were suppressed by increasing concentrations of AMP, with the IC₅₀ near 10 mM. (E) After glibenclamide, the AMP sensitivity increased with the IC₅₀ near 2 mM. (F) Plot of channel AMP sensitivity for Kir6.2+SUR1 before (○) and after (□) glibenclamide. In this case, fit of the data points yielded k = 9.5 mM before glibenclamide (n = 5) and k = 1.8 mM after glibenclamide (n = 5).