Potassium channel, an ion channel, can be found in virtually all species, except for some parasites. Potassium channels have transmembrane helices (TMs) spanning the lipid bilayer. Based on the structure and function, there are three major classes of the channel: the voltage-gated, inwardly rectifying, and tandem pore domain channels. Potassium channels locate in cell membranes and control transportation of K⁺ ions efflux from and influx into cells. They play crucial roles in both excitable and non-excitable cells. Specifically, in excitable cells, such asneurons, the delayed counterflow of potassium ions shapes the action potential. By contributing to the regulation of the action potential duration in cardiac muscle, malfunction of potassium channels may cause life-threatening arrhythmias.

hERG (the human Ether-à-go-go-Related Gene) is a gene that codes for a protein Kv11.1 (hERG), the alpha subunit of a potassium ion channel. hERG exists in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. Therefore, hERG is essential for normal electrical activity in the heart. Inherited mutations in the hERG gene cause long QT syndrome, a disorder that predisposes individuals to life-threatening arrhythmias. Blockade of hERG by its inhibitor can causes QT prolongation with an increase in risk of sudden cardiac arrest.

BAPTA-AM, an analog of BAPTA, is a selective Ca²⁺ chelator.

BAPTA-AM is a well-known membrane permeable Ca²⁺ chelator. And it shows highly selectivity for Ca²⁺ over Mg²⁺. BAPTA-AM inhibits neuronal Ca²⁺-activated K⁺ channel currents. What’s more, it can up-regulate the decreased cardiac sodium current density by chelating intracellular Ca²⁺. Meanwhile, BAPTA-AM inhibits hERG channels, hKv1.3 and hKv1.5 channels in HEK 293 cells. Importantly, BAPTA-AM prevents the toxicity of free radical, promotes apoptosis in non-neuronal cells and produces a beneficial effect in neuronal cells by protecting neurons from ischemic damage. In addition, BAPTA-AM displays antithrombotic activity in vitro.

In conclusion, BAPTA-AM is a well-known membrane permeable Ca²⁺ chelator. Besides, BAPTA-AM inhibits hERG channels, hKv1.3 and hKv1.5 channels in HEK 293 cells.

References:

Butler A, et, al. Front Pharmacol. 2020 Jan 24;10:1572.