Examples of transient modal gating (mode shifting) in BK channels taken from the study of McManus and Magleby (1988). (A) A continuous single-channel current record (divided into three traces) recorded from a single BK channel. The inside-out patch-clamp configuration (Hamill et al., 1981) was used to record the data. The patch of membrane was pulled from a skeletal muscle cell in a primary culture of rat skeletal muscle. Channel opening is upward. The downward and upward arrows indicate switching from normal mode gating into brief open mode gating and then back, respectively. (B) Stability plot of the moving average of open-interval durations taken 50 at a time. Shifting from normal mode gating, with a mean open interval duration of 2.8 ms, to brief open-mode gating, with a mean open interval duration of 0.5 ms, and then back to normal mode gating is readily apparent. (C and D) Current record (C) and stability plot (D) for mode shifting into and out of a buzz mode with a mean open interval of 0.05 ms. Symmetrical 144 mM KCl; 30 mV; 7.5 µM Ca²⁺_i; pH 7.2.