Open AccessMechanism of Histamine Release by Alpha-Chymotrypsin from Isolated Rat Mast Cells
Author(s) -
Junzo Sasaki
Publication year - 1975
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.25.311
Subject(s) - alpha chymotrypsin , histamine , chymotrypsin , mechanism (biology) , chemistry , alpha (finance) , mast (botany) , histamine h4 receptor , mast cell , pharmacology , microbiology and biotechnology , biochemistry , biology , histamine h2 receptor , enzyme , immunology , trypsin , medicine , receptor , philosophy , antagonist , construct validity , nursing , epistemology , patient satisfaction
Alpha-chymotrypsin (CT) was modified chemically and physically by the treatments with diisopropyl fluorophosphate, L-(1-tosylamide-2-phenyl) ethylchloromethylketone, hydrogen peroxide and heat. After these treatments, CT lost or decreased both the enzymic activity and ability of releasing histamine from rat mast cells. Ca++ was essential for histamine release by CT, while it enhanced only slightly the enzymic activity. Process of histamine release by CT could be separated into two stages: CT-dependent but not Ca++-dependent, and Ca++-dependent but not CT-dependent. The activated state of mast cells produced by CT decayed rapidly at 37 degrees C in the absence of Ca++, but these cells responded to Ca++ by adding CT once again, suggesting reconstitution of cell membrane structure affected by CT. Isoproterenol, epinephrine, prostaglandin E1, and dibutyryl-cyclic AMP (0.01-0.1 mM) did not inhibit release of histamine induced by CT. Neither theophylline (0.01-0.1 mM) alone nor the combinations of these cyclic AMP-active agents with theophylline inhibited the release of histamine. But, in the presence of papaverine (0.01-0.1 mM) a marked, dose-dependent inhibition was observed. These data suggest that 1) release of histamine by CT from rat mast cells is causally related to its hydrolytic activity, 2) this activity causes a reversible change on mast cell membrane which probably facilitates Ca++-influx through the cell membrane, and 3) there are subtle differences among CT, compound 48/80 and antigens concerning the effect of cyclic AMP-active agents in histamine-releasing mechanisms in mast cells.