Antiallergic agent, azelastine, inhibits (45)Ca uptake and histamine release in rat mast cells stimulated by antigen

The effect of antiallergic agent, azelastine, was examined in immunogical secretory process of mast cells. 1. Azelastine significantly inhibited (45)Ca uptake by mast cells stimulated by antigen, and the maximum inhibition was attained at a concentration of 50 μg/ml showing approximately 30.5 % inhibition. 2. Azelastine also inhibite the release of histamine from mast cells by antigen. The maximal inhibitory rate was 38.1%. The effect of azelastine on (45)Ca uptake and histamine release was dose-dependent, and compatible at employed cocentration of the agent. 3. Tachpylaxis to azelastine was not found in this experimental system.