[The effect of leukotriene B4 inhalation on airway responsiveness in dogs]

We studied the effect of leukotriene B4 (LTB4) inhalation on airway responsiveness in 12 dogs. LTB4 (10 micrograms/ml) was delivered as an aerosol, generated from a Devilbiss 646 nebulizer for ten minutes. Airway responsiveness to inhaled methacholine was determined by modified Astograph (7 Hz oscillation method) 1 hr (n = 6) and 6 hr (n = 6) after LTB4 inhalation. After measurement of airway responsiveness, total cell counts, differential cell counts, thromboxane B2 (TxB2) and 6-keto-prostaglandin (PG)F1 alpha levels in bronchoalveolar lavage fluid (BALF) were measured. The total cell counts in BALF increased after LTB4 inhalation (p less than 0.05), and the neutrophil counts in BALF increased significantly 1 hr (p less than 0.05) and 6 hr after (p less than 0.01) LTB4 inhalation. Airway responsiveness to inhaled methacholine decreased significantly 1 hr (p less than 0.05) and 6 hr (p less than 0.01) after LTB4 inhalation. There were no significant changes in the levels of TxB2 or 6-keto-PGF1 alpha in BALF 1 hr and 6 hr after LTB4 inhalation. These results suggest that inhaled LTB4 causes neutrophil recruitment into the airway but does not increase airway responsiveness to inhaled methacholine, and the possibility that LTB4 reduces airway responsiveness to inhaled methacholine exists in dogs.