Figure 7.

Inhibitors of the BLM K⁺ channel. (A) Dose– response curve for inhibition of the BLM K⁺ channel by external Ba²⁺. Relative nP _o (nP _o/nP _o,control) determined from outside-out patches at a command potential of −40 mV with KCl in the pipette and bath (solution d) is plotted versus [Ba²⁺]. The data at −40 mV were fitted with the Hill equation (solid curve), yielding a K _i = 460 μM and n _H = 0.90. The inhibition by Ba²⁺ is fully reversible. (B) Glibenclamide inhibits the BLM K_ATP channel. (top) A running average (window width 16 ms) of current versus time. Glibenclamide (500 μM) is added to the bath where indicated. (bottom) Sample traces from a representative experiment at −60 mV with KCl in the pipette and bath (solution d). Exposure of this inside-out patch to 500 μM glibenclamide reversibly decreases nP _o by ∼50%. The dashed line denotes the all channels closed (leak) current level and the dotted lines indicate each open channel level.