Fig. 3. Protein kinase A (PKA)-mediated adenosine triphosphate-sensitive potassium channel activation in native vascular smooth muscle cells. (  A ) Changes in the channel activity in response to a membrane permeable activator of PKA-dependent cAMP pathway, CPT-cAMP, added to the bath at 100 μm in cell-attached configuration. (  B ) Direct stimulatory effect of the catalytic subunit of PKA, c-PKA (100 U/ml), to the bath in inside-out patch configuration. Membrane potentials were clamped at −60 mV. Zero current levels are indicated by the  horizontal lines marked “0 pA.” Study drug was added to the bath solution as indicated by the  horizontal solid bars .