[Bronchial responsiveness to methacholine in the mouse tested by a new apparatus measuring respiratory resistance].

We developed a new apparatus for the measurement of mouse respiratory resistance (Rrs) by an oscillation method. Bronchial responsiveness to methacholine was studied in mice sensitized or not with egg albumin using this apparatus. All of the sensitized mice showed clearly increased bronchial reactivity upon nasal challenge with methacholine compared to normal control mice. The lung obtained from a sensitized mouse showed remarkable contraction of the bronchial smooth muscle, submucosal edema and cell infiltration around the bronchi. These results indicate that mouse Rrs is successfully measured by our newly developed apparatus and suggested that repeated sensitization of mice with allergen render their airway hyperreactive to methacholine.