Almitrine monomethanesulfonate

Almitrine monomethanesulfonate, a peripheral chemoreceptor agonist, inhibits selectively the Ca²⁺-dependent K⁺ channel. IC50 & Target: K⁺ channel^[1] In Vitro: Almitrine inhibits the activity of a high-conductance (152±13 pS), Ca²⁺-dependent K⁺ channel by decreasing its open probability. The IC₅₀ value of the effect is 0.22 μM. The inhibitory effect of Almitrine on Ca²⁺-dependent K⁺ channels also is observed in GH3 cells. Almitrine at concentrations up to 10 μM does not affect whole-cell voltage-dependent K⁺, Ca²⁺, or Na⁺ currents in rat or rabbit cells. However, this concentration of Almitrine significantly inhibits the Ca²⁺-dependent component of K⁺ currents in rat chemoreceptor cells^[1]. In Vivo: Almitrine acts via the peripheral arterial chemoreceptors raising carotid sinus nerve output and minute ventilation. Almitrine also has a pulmonary vascular action causing a dose-dependent constriction and dilatation. At low doses Almitrine enhances hypoxic pulmonary vasoconstriction and may improve the overall ventilation/perfusion ratio^[2].