Localized upregulation of BKCa channels via β2AR signaling. (A, B) Representative current traces of BKCa channels coexpressed with β2AR and AKAP79 in a Xenopus oocyte. Channel activity was recorded using cell-attached patch clamp during 20 ms, +150 mV test pulses from −50 mV, and then returned to −50 mV. Salbutamol (20 μM) was applied in the patch pipette by back-filling (A) or in the bath (B). A total of 100 sweeps were applied at various times as indicated. Sweeps 10, 40 and 80 at each time are shown. ‘c' represents closed state of the channel. Average currents of all 100 sweeps are shown at the bottom at the indicated times (min) after the GΩ seal formation (A) or bath application of salbutamol (B). (C) Total number of patches that have been recorded versus the number of patches in which an increased open probability of BKCa (Po increase >10%) was observed. Inclusion of salbutamol in the patch pipette significantly increased the number of patches which demonstrated Po increase as compared to bath application. Increased BKCa channel Po was dependent on coexpression of β2AR–AKAP79. (D) Graph of data set summarizing average currents of all 100 sweeps 15 min after salbutamol application. In the box plot, patches without Po increase are excluded. In each box, the mid-line shows the median value, the top and bottom lines show the 75th and 25th percentiles, and the whiskers show the 90th and 10th percentiles. The circles are means of data, including patches without Po increase, and error bars are standard error of means. For experiments on coexpression of BKCa, β2AR and AKAP, the P-value of Wilcoxon's rank sum test <0.0005 between pipette application of salbutamol and no salbutamol (left two circles), and <0.001 between pipette application and bath application of salbutamol (left and right circles).