PIP2 (1%) and 5% cholesterol, acute application of neomycin decreased the rate of K+ flux, with an IC50 of 15.0 ± 4.6 μM (Fig. 5c,d). The IC50 for neomycin inhibition is indistinguishable from that measured in the absence of cholesterol (Fig. 2d), suggesting little difference in the off-rate of PIP2. Thus, in addition to alcohol, cholesterol appears to directly activate GIRK2 channels through enhancement of the interaction with PIP2.
