title: Absence of mast cell involvement in active systemic anaphylaxis in rats.
abstract: This study investigates the role of mast cells in the hypotension induced by antigen-mediated anaphylaxis, compound 48/80 and dextran in mast cell-deficient white spotting (Ws/Ws) and normal wild type (+/+) rats. Rats were sensitized with 10 microg of intraperitoneal ovalbumin in saline or saline alone (sham-sensitized). Sensitized rats, both Ws/Ws and +/+ but not sham-sensitized rats, challenged intravenously with ovalbumin exhibited hypotensive responses. There was no evidence of mast cell activation in rat mesentery 20 min after intravenous antigen challenge in sensitized +/+ rats. Hypotension induced by intravenous injection of dextran (Dextran-162, 6%, 2 ml kg(-1)) or compound 48/80 (1 mg kg(-1)) occurred in +/+ rats, but not in Ws/Ws rats, and was inhibited by pretreatment with a combination of chlorpheniramine and cimetidine. Taken together, these data indicate that the hypotensive response induced by antigen-mediated anaphylaxis is independent of mast cell activation, whereas mast cell amines play the main role in the hypotensive response induced by dextran or compound 48/80.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, S-17177, Stockholm, Sweden. yancai.guo@fyfa.ki.se
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: P
authors.initials: P
authors.lastname: Hedqvist
authors.forename: L E
authors.initials: LE
authors.lastname: Gustafsson
mesh_terms: D000707:Anaphylaxis / Q000276:immunology / Q000503:physiopathology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015550:Cell Degranulation; D002744:Chlorpheniramine / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D003911:Dextrans / Q000494:pharmacology; D005838:Genotype; D006339:Heart Rate / Q000187:drug effects; D006632:Histamine / Q000008:administration & dosage; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology; D066298:In Vitro Techniques; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D008643:Mesentery / Q000166:cytology / Q000502:physiology; D010047:Ovalbumin / Q000276:immunology / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D003911:Dextrans; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D002744:Chlorpheniramine; D003189:p-Methoxy-N-methylphenethylamine; D002927:Cimetidine; D006632:Histamine; D010047:Ovalbumin