Lack of effect from a single cigarette challenge on bronchial responsiveness in healthy non-smoking subjects

The effect of smoking a cigarette on bronchial responsiveness was studied in healthy non-smokers. Twenty two subjects performed a methacholine inhalation test before and after smoking a single cigarette. Ten of the subjects took part in a further study in which propranolol was inhaled before the smoking challenge to diminish the baseline beta adrenergic tone of the airway. After they had smoked a single filtered or non-filtered cigarette the indices of bronchial responsiveness (the cumulative dose of methacholine starting a decrease in the reciprocal of resistance, Grs (Dmin), and the cumulative dose causing a 35% drop in the Grs (PD35Grs)) did not change significantly. With the inhalation of propranolol mean (SD) log Dmin decreased from 1.37 (0.44) units to 0.74 (0.57) (p less than 0.01) and log PD35Grs from 1.93 (0.38) to 1.51 (0.38) (p less than 0.01). Smoking a single cigarette after the inhalation of propranolol did not, however, cause any further change in bronchial responsiveness. This study suggests that smoking a single filtered or non-filtered cigarette does not change bronchial responsiveness in non-smokers, and that changes in beta adrenergic tone of the airway do not modify the effect of smoking a single cigarette on bronchial responsiveness.