title: Palytoxin both induces and inhibits the release of histamine from rat mast cells.
abstract: Palytoxin (PTX) is a potent releaser of histamine from rat mast cells. The concentration response curve is bell-shaped with its range between 0.05 ng/ml and 5 micrograms/ml and its maximum at 50 ng/ml. The release of histamine by PTX is specific because (a) heat-inactivated (50 degrees C) mast cells are insensitive to PTX, and (b) extracellular calcium is essential. Removal of extracellular potassium as well as the presence of borate shifts the curve to the left by factor of 10. At higher concentrations (5 micrograms/ml), PTX inhibits the release of histamine due to compound 48/80, MCD-peptide, Con-A, ionophore A-23187, and PTX itself.
mesh_terms: D000178:Acrylamides; D000818:Animals; D001881:Borates / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D003064:Cnidarian Venoms / Q000494:pharmacology*; D003208:Concanavalin A / Q000494:pharmacology; D004306:Dose-Response Relationship, Immunologic; D006636:Histamine Release / Q000187:drug effects*; D008407:Mast Cells / Q000276:immunology*; D010455:Peptides / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology; D000095702:Polyether Toxins
chemical_list: D000178:Acrylamides; D001881:Borates; D000001:Calcimycin; D002118:Calcium; D003064:Cnidarian Venoms; D003208:Concanavalin A; D010455:Peptides; D011188:Potassium; D003189:p-Methoxy-N-methylphenethylamine; C008331:mast cell degranulating peptide; C010272:palytoxin; D000095702:Polyether Toxins