Figure 7.

Phosphorylation-independent modulation of IRKC. A, Macroscopic IRKC was recorded from an outside-out patch configuration. The macroscopic current was sensitive to 1 mm Cs⁺, which is consistent with the whole-cell IRKC. B, An example shows that perfusion of 100 μm Sp-cAMP suppressed the macroscopic IRKC. C, A summary shows that cAMP can modulate IRKC in a phosphorylation-independent manner. Perfusion of 100 μm Sp-cAMP suppressed 25 ± 7% of the macroscopic IRKC (n = 5). Perfusion of 100 μm Rp-cAMP suppressed macroscopic IRKC by 13 ± 6% (n = 5). Perfusion of 20 μm H8 (relative current, 1.0 ± 0.02; n = 5) and 25 μm cBIMP (relative current, 0.99 ± 0.03; n = 5) did not alter the macroscopic IRKC, indicating that most of the downstream components of the intracellular signal cascade were disconnected from IRK channels in the outside-out patch configuration. Cnl, Control.