title: Platelet-activating factor (PAF) plays an important role in the immediate asthmatic response in guinea-pig by augmenting the response to histamine.
abstract: 1. To investigate the role of platelet activating factor (PAF) in the immediate asthmatic response, we examined the bronchial reactivity to histamine after administration of PAF to guinea-pigs or antigen challenge to passively sensitized guinea-pigs. 2. A bolus injection of PAF (20-40 ng kg-1), which did not cause a significant increase in intrathoracic pressure (ITP), augmented the bronchial response to histamine almost 8 fold. This airway hyperreactivity was observed even 1 min after PAF treatment. 3. A subthreshold dose of antigen (0.01 mg kg-1, i.v.) also provoked hyperreactivity to histamine, which became significant 6 and 11 min after the antigen treatment. 4. The specific PAF-antagonists, SM-10661 and CV-6209 (i.v.) dose-dependently inhibited both PAF- and antigen-induced airway hyperreactivities to histamine. 5. These results suggest that PAF plays an important role in antigen-induced acute airway responses by augmenting the activities of spasmogens.
authors.affiliation: Research Laboratories, Sumitomo Pharmaceuticals Co., Ltd., Osaka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Morooka
authors.forename: M
authors.initials: M
authors.lastname: Uchida
authors.forename: N
authors.initials: N
authors.lastname: Imanishi
mesh_terms: D000707:Anaphylaxis / Q000503:physiopathology; D000818:Animals; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D010047:Ovalbumin / Q000276:immunology / Q000502:physiology; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors / Q000502:physiology*; D010976:Platelet Count / Q000187:drug effects; D011726:Pyridinium Compounds / Q000494:pharmacology; D012129:Respiratory Function Tests; D013189:SRS-A / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D010972:Platelet Activating Factor; D011726:Pyridinium Compounds; D013189:SRS-A; D013844:Thiazoles; D053778:Thiazolidines; C053321:CV 6209; C065776:3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one; D006632:Histamine; D010047:Ovalbumin