Almitrine dimesylate

Almitrine dimesylate inhibits selectively the Ca2+-dependent K+ channel and that in rat chemoreceptor cellsused in the treatment of hypoxemic chronic lung diseases. (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. (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.