The mechanism of action of amiloride.

Amiloride induces a mild natriuresis as well as antikaliuresis. These changes in salt excretion are due to direct inhibition of the sodium channel in the apical plasma membrane of the distal nephron. Amiloride does not exert any direct or indirect inhibitory effect on apical potassium channels. The antikaliuretic effect is most likely a result of hyperpolarization of the apical plasma membrane and decrease in the electrochemical driving force for potassium movement across the apical membrane into the urinary space.