The effect of acute airway inflammation on bronchial reactivity in guinea pigs

This study compared airways reactivity before and after an inflammatory response was induced in the airways by exposing them to cigarette smoke. Airways reactivity was measured to graded doses of histamine using a standard technique in 24 animals without drug pretreatment, in 17 pretreated with propranolol, in 17 pretreated with atropine, and in 18 pretreated with both atropine and propranolol. In each group, at least 5 animals not exposed to cigarette smoke served as controls, and the remaining animals were studied in groups of 4 or more at 30 min, 6, and 24 h after exposure to 100 puffs of whole cigarette smoke. The data show that airways reactivity was increased at 30 min but not at 6 and 24 h after exposure to cigarette smoke. Pretreatment with propranolol or the combination of propranolol and atropine prior to the histamine dose-response curve did not affect the increased response seen after cigarette smoke exposure, but pretreatment with atropine abolished it. Comparing this study with our previous histologic studies of the airways in similarly exposed animals, we conclude that the observed increase in airways reactivity occurs during the fluid exudative phase of the inflammatory response before the polymorphonuclear leukocytes migrate into the epithelium.