Fig. 4.
Lack of an inhibitory effect of PMA on single BK channels recorded with cell-attached configuration in freshly isolated DSM cells under conditions of pharmacological inhibition of all major cellular sources of Ca2+ for BK channel activation. A: representative recordings of single BK channel currents measured at membrane potential of +60 mV prior to (control) and after addition of 100 nM PMA. C, closed channel state. B: single BK channel open probability (NPo) values over a 10-min interval before and after addition of 100 nM PMA for patch-clamp recording in A. C: summary data illustrating lack of an inhibitory effect of PMA (100 nM) on mean single BK channel NPo (n = 5, N = 5, P > 0.05). D: summary data demonstrating no change in mean single BK channel current amplitude in the presence and absence of 100 nM PMA (n = 5, N = 5, P > 0.05). All single-channel recordings were performed with thapsigargin (100 nM), ryanodine (30 μM), and nifedipine (1 μM) in the bath solution.