Potassium Assays – ION Biosciences https://ionbiosciences.com Fluorescent Ion Indicators | Assay Kits Fri, 06 Feb 2026 19:32:50 +0000 en-US hourly 1 https://wordpress.org/?v=7.1.3 https://ionbiosciences.com/wp-content/uploads/ION-Bio-100x100.png Potassium Assays – ION Biosciences https://ionbiosciences.com 32 32 Thallium-free hERG Potassium Channel Assay https://ionbiosciences.com/store/thallium-free-herg-potassium-channel-assay/ https://ionbiosciences.com/store/thallium-free-herg-potassium-channel-assay/#respond Fri, 01 Aug 2025 14:56:12 +0000 https://ionbiosciences.com/?post_type=product&p=34260 IPG-1 AM, our lowest affinity potassium indicator to measure changes in intracellular potassium concentration. This kit is optimized for hERG screening (Kv11.1), and can be used to identify activators and inhibitors of hERG channels.]]>

To facilitate safer and physiologically relevant evaluation of hERG channel activity, ION Biosciences has developed a Thallium-Free hERG Potassium Channel Assay utilizing ION Potassium Green 1 AM (IPG-1 AM), a membrane-permeable, fluorescent dye sensitive to intracellular potassium levels. 

Upon membrane depolarization, hERG channels open and mediate potassium efflux, causing a decrease in intracellular potassium concentration. This drop in intracellular potassium levels is detected in real time as a reduction in IPG-1 fluorescence intensity, providing a direct measure of channel function.

This direct-readout eliminates the need for surrogate ions or radioactive tracers and enables robust, high-throughput screening to identify hERG modulators in 96- and 384-well formats. 

Series of graphics showing how the Thallium-free hERG Channel Assay works

The Thallium-Free hERG Potassium Channel Assay provides reliable EC50/IC50 values and is ideally suited for pharmacological profiling, cardiotoxicity safety screening, and therapeutic discovery for hERG channels. 

This kit has not yet been validated for use with additional voltage-gated potassium channels at this time. 

All data displayed was generated using our stable HEK293 hERG cell line. 

Identify inhibitors: Compounds that inhibit hERG activity, such as terfenadine, do not display a loss of fluorescence after treatment with a depolarizing stimulus solution to activate the channel.

Kinetic traces and corresponding concentration response curve showing hERG inhibition by terfenadine measured using the thallium-free hERG channel assay.

Large screening windows in inhibitor modes with Z’ > 0.9 to enable reliable inhibitor detection. 

Graphs showing kinetic traces of hERG expressing cells treated with or without terfenadine, and corresponding Z' calculation in a 384-well format.

Titrate stimulus solution for optimal screening windows: Adding different concentrations of  the depolarizing stimulus solution can result in more channel activity and greater potassium efflux.

Graphs showing kinetic traces of IPG-1 fluorescence in hERG expressing cells after treatment with various concentrations of a depolarizing stimulus solution.
]]> https://ionbiosciences.com/store/thallium-free-herg-potassium-channel-assay/feed/ 0 Thallium-free GIRK Potassium Channel Assay https://ionbiosciences.com/store/thallium-free-girk-potassium-channel-assay/ Tue, 03 Jun 2025 21:09:38 +0000 https://ionbiosciences.com/?post_type=product&p=34007 Thallium-free GIRK Potassium Channel Assay is the first fluorescence-based potassium channel solution that directly measures potassium flux, enabling you to move away from thallium-containing products. This product features the potassium-sensitive dye, IPG-1 AM, our lowest affinity potassium indicator to measure changes in intracellular potassium concentration. This kit is optimized for GIRK (Kir3.x) screening, and can be used to identify activators and inhibitors of GIRK channels.]]>

Traditional approaches for measuring GIRK activity such as patch clamp, FRET, or thallium flux assays can be labor-intensive, low-throughput, or reliant on toxic surrogate ions. To overcome these limitations, ION Biosciences built the Thallium-Free GIRK Potassium Channel Assay featuring ION Potassium Green-1 AM (IPG-1 AM), a membrane-permeable, potassium-sensitive, fluorescent indicator that directly measures potassium flux.

Upon binding of an agonist to Gi/o-coupled GPCRs or direct activation of GIRK channels, potassium ions flow through the channel and out of the cell, resulting in a measurable decrease in intracellular potassium concentration. This change in potassium concentration is detected in real-time by IPG-1 as a loss of fluorescence intensity. This direct-readout eliminates the need for surrogate ions or radioactive tracers and enables robust, high-throughput screening to identify GIRK modulators in 96- and 384-well formats. 

The Thallium-Free GIRK Potassium Channel Assay provides reliable EC50/IC50 values and is ideally suited for pharmacological profiling and discovery of therapeutic compounds targeting GIRK channels or GIRK channel-coupled pathways.

This kit has not been validated for use with additional potassium channel targets at this time.

GIRK potassium channel assay illustration

Data

All data displayed was generated using our stable HEK293 – huKir3.1/3.2 cell line. 

Identify activators: Compounds that increase GIRK activity, such as ML297, exhibit a concentration dependent loss of intracellular fluorescence, indicative of K+ efflux.

GIRK potassium channel assay to identify Kir3 inhibitors. Kinetic traces and dose response curves for SCH23390, a selective GIRK inhibitor.

Identify inhibitors: Compounds that inhibit GIRK activity, such as SCH23390, do not display a loss of fluorescence upon treatment with a potent activator such as ML297.

Large screening windows in activator and inhibitor modes with Z’ > 0.8 enable reliable hit-finding campaigns.

GIRK potassium channel assay displays high Z’ values for hit identification in activator and inhibitor screening modes
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