title: Different classes of PAF-antagonists block norepinephrine-induced vascular escape and tachyphylaxis in the isolated rabbit kidney.
abstract: In order to study the role of platelet activating factor (PAF) on norepinephrine induced vascular escape and tachyphylaxis, compounds from different pharmacological families sharing PAF-antagonistic activity, were infused in the isolated rabbit kidney perfused with Krebs-Henseleit solution. A natural compound derived from Ginkgo biloba (BN 52020, 1.1 x 10(-6) M), a triazolobenzodiazepine substance (WEB 2170, 1.1 x 10(-6) M) and a dihydropyridine derivative lacking cardiovascular effects (PCA 4248, 2.7 x 10(-6) M), were analysed. The vascular reactivity to three cycles of norepinephrine (1.3 x 10(-6) M), infused in the kidneys treated with each of the PAF- antagonists, were evaluated for vascular escape and tachyphylaxis. The results demonstrated a significant reduction of both regulatory phenomena. A fall in renal vascular escape promoted by PAF antagonists, from a control level of 50.32 +/- 4.61 to 27.64 +/- 8.01% (p < 0.05), suggests a role for PAF-acether in the vascular adjustment of the mammalian kidney.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde-UFC, Fortaleza-CE. Brazil.
authors.forename: M G
authors.initials: MG
authors.lastname: Ferreira
authors.forename: M C
authors.initials: MC
authors.lastname: Fonteles
mesh_terms: D000818:Animals; D001381:Azepines / Q000494:pharmacology; D004095:Dihydropyridines / Q000494:pharmacology; D046934:Ginkgolides; D066298:In Vitro Techniques; D007668:Kidney / Q000098:blood supply / Q000187:drug effects*; D007783:Lactones / Q000494:pharmacology; D009638:Norepinephrine / Q000037:antagonists & inhibitors*; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors*; D011817:Rabbits; D013618:Tachyphylaxis; D014230:Triazoles / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D001381:Azepines; D004095:Dihydropyridines; D046934:Ginkgolides; D007783:Lactones; D010972:Platelet Activating Factor; D014230:Triazoles; C066024:PCA 4248; C063964:bepafant; C477042:ginkgolide A; D009638:Norepinephrine