MECHANISM OF BRADYKININ-INDUCED HISTAMINE-RELEASE FROM RAT PERITONEALMAST-CELLS

Bradykinin at concentrations higher than 2 mu M caused a significant h istamine release from rat peritoneal mast cells when estracellular Ca2 + was removed from the medium. Under the same experimental conditions, bradykinin increased Ca2+ release from the intracellular Ca store of the rat peritoneal mast cells, and a clear relationship was observed b etween the magnitude of histamine release and an increase in fluoresce nce intensity. Addition of Ca2+ to the medium resulted in an inhibitio n of the response to bradykinin in a concentration-dependent manner. A lmost the same results were obtained when Mg2+, Ba2+ and La3+ were add ed to the medium. Neither B-1 nor B-2 antagonists caused significant a ntagonistic effects on histamine release induced by bradykinin. Howeve r, B-2 antagonists caused a histamine release of the same potency as b radykinin when applied alone. These results indicate that bradykinin-i nduced histamine release is not attributable to a bradykinin receptor.