Absence of K_ATP current in aortic smooth muscle cells isolated from Sur2^–/– mice. (a) Examples of original whole cell current traces recorded in a Sur2^+/+ and a Sur2^–/– aortic smooth muscle cell 2 minutes after cell rupture (maximal potassium channel current [I_K], left), after 20 μM of glibenclamide (GLB, middle), and the GLB-sensitive I_KATP obtained by subtraction (right). The glibenclamide-sensitive current was interpreted as K_ATP current and was normalized by cell capacitance to obtain the whole cell current density. The GLB-sensitive current was absent from the Sur2^–/– cell. (b) Whole cell current protocol. The cell was held at –70 mV, and 235 ms test pulses from –90 to 10 mV were delivered to induce a whole cell current. (c) Mean summary data of the current voltage plot for the GLB-sensitive I_KATP density at all voltages tested (n = 13 cells from five Sur2^+/+ mice vs. n = 14 cells from four Sur2^–/– mice, *P < 0.05).