BK channel activity in vascular smooth muscle cells from WT and BK^−/− mice. To confirm the presence and normal function of BK channels in WT mice, vascular smooth muscle cells from BK^+/+ and BK^−/− mice were subjected to patch clamp (A). Bars (mean ± SD) represent the mean current amplitudes measured at 100 mV (B). n cells ≥ 6, each bar. *P < .05.