Increased airway mucosal permeability of smokers. Relationship to airway reactivity.

We studied pulmonary epithelial permeability and bronchial reactivity in 10 smoking and 8 nonsmoking adults. Permeability was measured as the disappearance half-life (T 1/2) of aerosolized 99mTc-DTPA from the lungs, and a permeability index (PI) calculated that reflected the appearance of the tracer in the blood. Smokers had increased permeability with a T 1/2 of 44.6 +/- 12.2 min and PI values at 10, 25, and 60 min of 27.3 +/- 13.2, 32.5 +/- 10.2, and 34.3 +/- 9.9, compared with those in nonsmokers with a T 1/2 of 110.0 +/- 62.7 min and PI values of 9.4 +/- 5.7, 14.9 +/- 8.3, and 23.1 +/- 9.0. Bronchial reactivity to histamine was measured with and without prior exposure to aerosolized propranolol (to achieve beta-blockade of airway smooth muscle). Reactivity increased significantly (p less than 0.001) in both groups after beta-blockade, but no difference was found between smokers and nonsmokers. Despite the increased permeability in smokers, there was no evidence of increased reactivity.