Characteristics of and Calcium Requirements for Histamine Release from Rat Peritoneal Mast Cells Treated with Concanavalin A

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Abstract
Concanavalin A (Con A) produced a selective release of histamine from rat peritoneal mast cells in the presence and absence of added calcium. Secretion under both conditions was enhanced by adenosine, but only the former release was potentiated by phosphatidyl serine (PS). The latter release was abolished by depletion of intracΕllular reservoirs of calcium and probably reflected mobilization of these stores. A brief exposure to chelating agents enhanced the response to Con A whereas supramaximal concentrations of calcium depressed the response. This result suggests that superficial calcium-stores in the membrane may regulate movement of the cation into the cytosol. The activated state induced by Con A and PS was particularly stable and did not decay with time over a 30 min period. The kinetics of the release process were independent of added calcium, indicating that calcium-translocation is not the rate-limiting step in the exocytotic mechanism.