title: Airway and pulmonary tissue responses to platelet-activating factor in rats.
abstract: We studied airway and pulmonary tissue responses to platelet-activating factor (PAF) in rats by measuring alveolar pressure with the alveolar capsule technique. We calculated airway resistance (Raw), dynamic elastance (Edyn), and pulmonary tissue resistance (Rtis). PAF was administered intravenously in doses of 0.1, 1, 10, and 30 micrograms (1 dose per animal, 5 rats for each dose). Infusion of PAF resulted in a significant increase in Rtis and Edyn (p < .05). Maximal values of Edyn were observed with the infusion of 10 micrograms of PAF (p < .02). Rtis presented a significant increase after infusion of 1 microgram of PAF (p < .05). The observed increase in Raw was transient and did not reach statistical significance. After infusion of PAF lungs were fixed by a quick-freezing method. Morphometric analysis showed that PAF infusion resulted in significant increases in intraluminal secretion (p = .001) and peribronchiolar edema (p < .001) but did not result in significant airway contraction. We conclude that intravenous infusion of PAF results in significant effects on lung tissue mechanics. The effects of PAF on the mechanical properties of lung parenchyma reflect the inflammatory alterations induced by this agonist in distal airspaces.
authors.affiliation: Departamento de Patologia, Faculdade de Medicina, Universidade de São Paulo, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Garcia
authors.forename: P S
authors.initials: PS
authors.lastname: Paiva
authors.forename: M
authors.initials: M
authors.lastname: Dolhnikoff
authors.forename: S
authors.initials: S
authors.lastname: Jancar
authors.forename: P H
authors.initials: PH
authors.lastname: Saldiva
authors.forename: M A
authors.initials: MA
authors.lastname: Martins
mesh_terms: D000403:Airway Resistance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004548:Elasticity; D007262:Infusions, Intravenous; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D015656:Respiratory Mechanics / Q000187:drug effects*; D014783:Viscosity
chemical_list: D010972:Platelet Activating Factor