PIP₂ action on native BK channels in isolated skeletal muscle myocytes. (A) Unitary currents from an I/O patch obtained before (top) and after (bottom) a 5-min bath application of 10 μM PIP₂ show that the phosphoinositide causes an increase in BK NP_o that is markedly reduced when compared with that evoked by PIP₂ in vascular myocyte BK channels (Fig. 1, A and C). Arrowheads, baseline; upward deflections, channel openings. (B) Averaged PIP₂ responses of native skeletal muscle BK channels; *, P < 0.05; n = 4; V = 40 mV, Ca²⁺_i = 10 μM.