A novel membrane potential-sensitive fluorescent dye improves cell-based assays for ion channels

Area of Science:

• Cellular Electrophysiology
• Fluorescent Dye Technology
• Ion Channel Research

Background:

• Conventional bisoxonol fluorescent dyes like DiBAC(4)(3) have limitations in membrane potential assays, including slow response times and complex preparation.
• These limitations hinder the accuracy and throughput of assays measuring ion channel activity.

Purpose of the Study:

• To characterize the FLIPR Membrane Potential Assay Kit (FMP) for measuring membrane potential changes in cells expressing ion channels.
• To compare the performance of FMP with DiBAC(4)(3) in terms of kinetics and amplitude of fluorescence signals.

Main Methods:

• Utilized FLIPR and whole-cell patch-clamp recording to assess FMP and DiBAC(4)(3) in cells with voltage- and ligand-gated ion channels.
• Compared steady-state and kinetic fluorescence properties of FMP and DiBAC(4)(3).
• Investigated responses to depolarization (hElk-1 channel) and ligand activation (vanilloid receptor-1).

Main Results:

• FMP demonstrated a 14-fold faster response than DiBAC(4)(3) to depolarization in cells expressing the hElk-1 channel.
• FMP fluorescence changes kinetics closely matched electrophysiological recordings, showing concentration-dependent increases with KCl.
• FMP exhibited superior kinetics and amplitude for capsaicin-induced fluorescence changes in vanilloid receptor-1 studies.

Conclusions:

• The FLIPR Membrane Potential Assay Kit (FMP) is a novel and powerful tool for membrane potential assays.
• FMP offers significant advantages over traditional dyes, enabling faster and more sensitive detection of ion channel activity.
• This dye facilitates the development of high-throughput screening assays for ion channels.