Fig. 5: Progesterone activation of BK channel activity by the β1 regulatory subunit and the importance of the high-affinity site are sustained in native smooth muscle membranes.
From: Progesterone activation of β1-containing BK channels involves two binding sites
a Example records of the activation of inside-out (I/O) patches of smooth muscle myocyte BK channel activity harvested from C57BL/6 mice before (top) and during (bottom) 10 μM PROG. Channel openings are shown as downward deflections; black arrows indicate the baseline with no channel activity. b Example records of the activation of inside-out patches of smooth muscle myocyte BK channel activity harvested from KCNMB1-/- mice before (top) and during (bottom) 10 μM PROG. All records were recorded in 30 μM free-Ca2+ at 30 mV transmembrane voltage. Channel openings are shown as downward deflections; black arrows indicate the baseline with no channel activity. c Averaged data showing NPo/NPobasal as a function of time, comparing channel activity in the presence of the vehicle control or PROG in either C57BL/6 or KCNMB1-/- mice. Black arrows indicate the time of change in perfusion (either bath perfusion or PROG perfusion). Data are shown as mean ± SEM; n = 5 for each group. *Statistically significant from vehicle control (P = 0.0425, 0.0366, 0.0426, 0.025, 0.0120, 0.0312, 0.0320, 0.0425, 0.0312 and 0.0425; two-sided Mann–Whitney U-test). d Averaged maximal effects of channel activity from C57BL/6 and KCNMB1-/- mice, in the presence of 10 μM PROG or the vehicle control. Geometric shapes indicate individual records. Data are shown as mean ± SEM; n = 5 for each group. *Statistically significant from vehicle control (P = 0.01208; two-sided Mann–Whitney U-test).
