BRONCHIAL RESPONSE TO INHALED HISTAMINE IN ASYMPTOMATIC YOUNG SMOKERS

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  • 1 January 1983
    • journal article
    • research article
    • Vol. 64  (3) , 207-211
Abstract
Nonspecific bronchial response to inhaled histamine was measured in 21 young (21.2 .+-. 1.9 yr) asymptomatic smokers (2.9 .+-. 2.1 pack yr) and in 21 age, sex and height matched asymptomatic controls. Following a 2 min incubation of histamine 8 mg/ml, the smokers showed smaller reduction in FEV1 [forced expiratory volume in 1 s] (3.4 .+-. 3.3% vs. 7.0 .+-. 6.3%, P < 0.05) and in MMF [maximum mid-expiratory flow] (7.6 .+-. 15.6% vs. 21.1 .+-. 17.3%, P < 0.02) than did the nonsmokers. The threshold concentration of histamine was defined as that concentration where FEV1 consistently was > 2 SD below the mean of that obtained from 5-7 prehistamine spirograms. A histamine threshold between 2-8 mg/ml was detectable in 7 smokers and a threshold between 1-8 mg/ml was seen in 14 nonsmokers. Histamine threshold was not measurable (> 8 mg/ml) in 14 smokers and 7 nonsmokers (P < 0.05). These young asymptomatic smokers of brief duration failed to show increased response to histamine; they appeared to respond less to histamine than did matched controls. This may be the result of selection (who choses to smoke) or alternatively it may be due to an acquired loss of sensitivity (development of tolerance) to inhaled irritants.