Trapidil, a coronary vasodilator, inhibits IgE-mediated histamine release from human basophils

The effect of trapidil, a coronary vasodilator, on histamine release from human basophils was studied. Trapidil inhibited IgE-mediated, anti-IgE-induced histamine release in a dose-dependent fashion (ID50 : 5.8 x 10(-4) M). In contrast, histamine release induced by calcium ionophore A23187, formyl-L-methionyl-L-leucyl-L-phenylalanine and polymyxin B was not affected by this agent. Two-stage experiments suggested that the effect of trapidil was exerted not only on the first Ca2+-independent activation stage, but also on the second Ca2+-dependent stage. These results, together with recent reports that trapidil has a bronchodilator action, suggest that trapidil could be used in the treatment of asthmatic patients.