Contents of the Mast Cell Granules Active agent Activity Histamine Increases vascular permeability;elevates level of cyclic AMP Heparin Anticoagulation Serotonin Increases vascular permeability SRS-A Increases vascular permeability;causes contraction of human broncholes Chymase Proteolysis Hyaluronidase Increases vasuclar permeability Eos.Chem.Factor Chemoattraction of eosinophils Neut.Chem.Factor Chemoattraction of neutrophils Platelet Agg.Factor Aggregates platelets Contents of the Mast Cell Granules Active agent Activity Histamine Increases vascular permeability; elevates level of cyclic AMP Heparin Anticoagulation Serotonin Increases vascular permeability SRS-A Increases vascular permeability; causes contraction of human broncholes Chymase Proteolysis Hyaluronidase Increases vasuclar permeability Eos. Chem. Factor Chemoattraction of eosinophils Neut. Chem. Factor Chemoattraction of neutrophils Platelet Agg. Factor Aggregates platelets