Quercetin: a novel inhibitor of Ca2+ influx and exocytosis in rat peritoneal mast cells.

The effect of the transport ATPase inhibitor, quercetin on histamine secretion from antigen sensitized mast cells was examined. At micromolar concentrations, quercetin had an immediate inhibitory effect on histamine secretion mediated by antigen, concanavalin A and ATP but it had little effect on release induced by the ionophores A23187 and X537A. Quercetin exerts its effect after the binding of the releasing ligands and the distinction between its effect on ligand induced and A23187 induced secretion suggests that it affects the normal path of Ca2+ entry into the cell. The inhibitory effects of quercetin were compared with those of the structurally related anti-allergic drugs cromoglycate and AH7725.