Guangxitoxin 1E

Guangxitoxin 1E is a potent and selective blocker of K_V2.1 and K_V2.2 channels. Guangxitoxin 1E inhibits K_V2 with an IC₅₀ of 1-3 nM. K_V2 channels underlie delayed-rectifier potassium currents in various neurons^[1][2]. IC50 & Target:IC50: 1-3 nM (K_V2 channels); 24-54 nM (K_V4.3 channels)^[2] In Vitro: Guangxitoxin 1E inhibits K_V2 with an IC₅₀ of 1-3 nM but has no significant effect on K_V1.2, K_V1.3, K_V1.5, K_V3.2 and BK potassium channels, nor on calcium and sodium channels Ca_V1.2, Ca_V2.2, Na_V1.5, Na_V1.7, Na_V1.8, whereas the IC₅₀ for K_V4.3 channels is 24-54 nM^[2].
In mouse β-cells, Guangxitoxin 1E inhibits 90% of I_DR and, as for K_V2.1, shifts the voltage dependence of channel activation to more depolarized potentials, a characteristic of gating-modifier peptides. Guangxitoxin 1E broadens theβ-cell action potential, enhances glucose-stimulated intracellular calcium oscillations, and enhances insulin secretion from mouse pancreatic islets in a glucose-dependent manner^[2].