title: Studies on the mechanism of PAF-induced vasopermeability in rat lungs.
abstract: The present study evaluated the effect of platelet activating factor (PAF) instilled into rat airways on vascular permeability assessed in isolated lung tissues by Evans blue (EB)-labelled plasma protein extravasation. It was found that intratracheal instillation of PAF induces a dose-dependent increase of EB extravasation in the bronchi (upper and inner) but not in the lung parenchyma. The contribution of eicosanoids to PAF-induced increase of vascular permeability was investigated by treating the animals with selected inhibitors prior to PAF administration. Mepacrine (5 mg/kg), L-663,536 (10 mg/kg), indomethacin (4 mg/kg) and dazoxiben (10 mg/kg) significantly reduced EB extravasation in the bronchi. The PAF antagonists BN-52021 (5 mg/kg), WEB-2086 (1 mg/kg), WEB-2170 (5 mg/kg) and PCA-4248 (3 mg/kg) were all effective in reducing the extravasation. These results suggest that PAF-induced increase of vascular permeability in rat bronchi is mediated by cyclooxygenase and lipoxygenase products of arachidonic acid metabolism.
authors.affiliation: Departamento de Farmacologia, Universidade de São Paulo, Brasil.
authors.forename: W T
authors.initials: WT
authors.lastname: de Lima
authors.forename: F H
authors.initials: FH
authors.lastname: Kwasniewski
authors.forename: P
authors.initials: P
authors.lastname: Sirois
authors.forename: S
authors.initials: S
authors.lastname: Jancar
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D001980:Bronchi / Q000098:blood supply; D002199:Capillary Permeability / Q000187:drug effects*; D005070:Evans Blue; D005119:Extravasation of Diagnostic and Therapeutic Materials; D007093:Imidazoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008168:Lung / Q000098:blood supply*; D008297:Male; D010972:Platelet Activating Factor / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011796:Quinacrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014132:Trachea
chemical_list: D001798:Blood Proteins; D007093:Imidazoles; D010972:Platelet Activating Factor; C029166:dazoxiben; D005070:Evans Blue; D011796:Quinacrine; D007213:Indomethacin