Amantadine Hexamethylene amiloride, the active tautomer E protein is an unscrupulous ionic channel, which can conduct both anions and cations. The conductivity preference is dependent on pH and the lipid constituents of the membrane. In physiological conditions it appears to have slight preference for cations (Na + , K + , Ca 2+ ) . The simplest blocking mechanism would be if the cationic headgroup is dragged into the channel by the electric field, with the hydrophobic group following and plugging the entry for the succeeding ions.