Validation of FLIPR membrane potential dye for high throughput screening of potassium channel modulators

A fluorescence-based assay using the FLIPR Membrane Potential Assay Kit (IM P) was evaluated for functional characterization and high throughput screen ing (HTS) of potassium channel (ATP-sensitive K+ channel; K-ATP) modulators . The IMP dye permits a more sensitive evaluation of changes in membrane po tential with a more rapid response time relative to DiBAC(4)(3). The time c ourse of responses is comparable to ligand-evoked activation of the channel measured by patch-clamp studies. The pharmacological profile of the K+ cha nnel evaluated by using reference K-ATP channel openers is in good agreemen t with that derived previously by DiBAC(4)(3)-based FLIPR assays. Improved sensitivity of responses together with the diminished susceptibility to art ifacts such as those evoked by fluorescent compounds or quenching agents ma kes the IMP dye an alternative choice for HTS screening of potassium channe l modulators.