Comparison of inactivation onset and tail current during recovery from inactivation for β2- and β3a-mediated inactivation at 10 μM [Ca ²⁺ ] _in . (A) Inactivation mediated by mβ3a with protocol shown on the top. (B) Current inactivation with hβ2. (C) Trace shows a single α+β3a channel tested with the indicated protocol. The channel activates and inactivates upon depolarization, upon repolarization to −160 mV immediately reopens to an open level of reduced apparent conductance level, then opens to a fully open BK current level before closing. Finally, the channel reopens upon depolarization, indicative that it has recovered from inactivation. The inset highlights this behavior, displaying the entire current record between repolarization and subsequent depolarization, indicated by red vertical lines. Horizontal dotted lines indicate the 0-current level, subconductance level, and the amplitude of the unresolved final full opening. (D) Traces illustrate behavior of a single α+β2 channel, which inactivates but exhibits no tail opening upon repolarization, although the channel is available for opening with subsequent depolarization. (E) Mean + SD of inactivation time constants for 8 β3a patches and 6 β2 patches measured at +160 mV.