ON THE MECHANISM OF ACTION OF SODIUM ORTHOVANADATE IN INDUCING HISTAMINE-RELEASE FROM RAT PERITONEAL MAST-CELLS

Sodium orthovanadate produced a dose-dependent release of histamine an d prostaglandin D2 from rat peritoneal mast cells. The release of hist amine was selectively inhibited by the anion channel blockers SITS and DIDS, and by theophylline and dibutyryl cyclic-AMP, but was unaffecte d by disodium cromoglycate and lanthanum ions. Unlike IgE-directed lig ands, vanadate did not produce any change in the intracellular concent ration of cyclic-AMP but did promote a substantial uptake of calcium-4 5 from the incubation medium. This effect paralleled the release of hi stamine. These results are discussed in terms of the possible mode of action of vanadate.