The purpose of this investigation was to determine if the variability of bronchial responsiveness to inhaled histamine in normal subjects is related to the total dose of histamine deposited in the airways. To test this possibility, we used a new method of histamine challenge that permits calculating the histamine mass deposited in the airways in an attempt to correlate it with the magnitude of the response. Using a standardized breath-holding maneuver, 10 healthy nonsmokers and 10 healthy smokers with normal spirometry inhaled an aerosol generated from a solution containing a fixed ration of histamine and a small quantity of hematoporphyrin serving as a fluorescent tracer. The mass of histamine deposited was calculated from the measured fluorescence of the inspired and expired aerosol. Forced expiratory volume in one second (FEV1) was measured before and 10 min after inhalation challenge. There was a negative correlation between percent decrease in FEV1 (ΔFEV1) and histamine mass deposited in the nonsmokers (r = -0.83, p < 0.005) and smokers (r = -0.82, p < 0.005) without a difference between the 2 slopes. The range of ΔFEV1 was 7 to 33% and of histamine mass deposited, 0.03 to 0.18 mg in the nonsmokers. The respective values in the smokers were 2 to 30% and 0.03 to 0.17 mg. In 6 subjects in whom dose-response curves were obtained, the mean deposited histamine mass required to decrease the FEV1 by 10% was 0.11 mg. We conclude that in normal nonsmokers and smokers, the variability in bronchial responsiveness to a standard histamine aerosol challenge is related to differences in the dose deposited in the airways.
|Original language||English (US)|
|Number of pages||5|
|Journal||American Review of Respiratory Disease|
|State||Published - 1985|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine