[Effects of inhaled aerosol of platelet activating factor on pulmonary function and airway responsiveness in normal subjects]

Abstract

Platelet activating factor (PAF), which was given as an aerosol to normal subjects, caused immediate bronchoconstriction. After the first inhalation of PAF, percentage fall of VP30 was 43.2% +/- 7.1% at five minute. Subsequent inhalations of PAF, bronchoconstriction effect of PAF gradually attenuated. There was an increase in the airway responsiveness to methacholine following inhalation of PAF. The mean PC40 fell from 18.57 +/- 1.69 g.L-1 to 7.01 +/- 2.24g.L-1 (P < 0.01) on day three and returned to baseline in 1 to 2 weeks. DLCO decreased from 3.3 +/- 0.7ml.kPa-1/s to 2.9 +/- 0.4ml.kPa-1/s (P < 0.01) on day three. Chlorpheniramine partially inhibited the bronchoconstriction effect of PAF in a double blind, crossover study. These data suggest that PSF may contribute to the pathogenesis of airway hyperresponsiveness in asthma and the bronchoconstriction induced by inhaled PAF is mediated in part by histamine release.