Figure 5. S4_STREXA is activated by PKA and is modulated by DEX.

Summary of the effect of cAMP application to the intracellular face of patches from HEK 293 cells expressing S4_STREXA channels pre-treated for 2 h with vehicle (n = 8) or 1 μm, dexamethasone (n = 8) prior to patch excision. The specific PKA inhibitor peptide PKI_5–24 was applied to the intracellular face of inside-out patches 5 min before application of cAMP in vehicle (n = 4) or dexamethasone-treated (n = 4) cells. ATPγS, in the presence (n = 4) or absence (n = 6) of PKI_5–24, and okadaic acid (Ok, 2 nm) (n = 3) were applied as in Fig. 3. All data are expressed as the percentage change of pre-treatment BK channel activity measured at +40 mV in the presence of 0.2 μm[Ca²⁺]_i and 1 mm ATP as described in Methods. The bars show means and s.e.m. **P < 0.01 compared with vehicle-treated cAMP group.