| Abstract: | Abstract— The effect of okadaic acid, a potent inhibitor of protein phosphatase 1 and 2A, on histamine release from mast cells has been investigated. Okadaic acid strongly and dose-dependently inhibited histamine release from mast cells induced by anti-IgE. The IC50 value of okadaic acid on histamine release induced by anti-IgE was 3·2 Nm. However, okadaic acid failed to inhibit histamine release induced by A23187 and compound 48/80. Moreover, okadaic acid showed no effect on the initial rise in intracellular Ca2+, Ca2+-mobilization from intracellular Ca2+-stores and the generation of inositol trisphosphate. These results suggest a possible involvement of protein phosphatase 2A in the histamine release from mast cells induced by anti-IgE. |
