Open AccessEffects of Platelet-Activating Factor on Rat Airways
Author(s) -
Miwa Misawa,
Tatsuyuki Takata
Publication year - 1988
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.48.7
Subject(s) - bronchoconstriction , platelet activating factor , histamine , inhalation , tachyphylaxis , chemistry , methacholine , pharmacology , medicine , endocrinology , anesthesia , asthma , lung , respiratory disease
Effects of platelet-activating factor (PAF) on the rat airways were investigated. Male Wistar rats were anesthetized, and PAF was inhaled into the lungs through a tracheal cannula for 5 min using an ultrasonic nebulizer. The bronchomotor response was measured with a modified Konzett-Rössler method in rats immobilized with decamethonium bromide. The inhalation of PAF caused a marked bronchoconstriction, dose-dependently, in a concentration range of 0.0001 to 0.01%. The bronchoconstrictor potency of PAF was about ten times higher than that of ACh. On the other hand, histamine inhalation gave only a slight bronchoconstriction even at the high concentration of 0.1%. The bronchomotor response to PAF was accompanied by a marked, sustained decrease in systemic blood pressure, in a dose-dependent manner. Repeated inhalations of PAF (0.001%) at an interval of 60 min resulted in a pronounced tachyphylaxis in the bronchoconstrictor response, but not in the hypotensive response. Combined inhalations of PAF with ACh or histamine did not produce a potentiation by PAF of the bronchoconstrictor responses to ACh and histamine. These findings show that PAF is a strong bronchoconstrictor agent in rats and that there is no interaction between PAF and other mediators in the acute bronchoconstrictor response.