Consecutive allergen challenges resulted in decreased bronchial responsiveness / 中华医学杂志(英文版)

ABSTRACT

<p><b>OBJECTIVE</b>To investigate bronchial responsiveness to acetylcholine in allergic airway inflammation of SD rats.</p><p><b>METHODS</b>SD rats were immunized and challenged by chicken ovalbumin (OVA). Airway responsiveness, acetylcholine (Ach) provocation concentration needed to increase baseline airway resistance by 200% (PC(200)) were measured.</p><p><b>RESULTS</b>The value of baseline airway resistance in asthma group was significantly higher than that in control group (2.282 +/- 0.128 vs 3.193 +/- 0.239; P < 0.01). After multiple ovalbumin exposures, airway responsiveness to intravenous injection of acetylcholine decreased significantly (-LogPC(200) 4.006 +/- 0.554 vs 2.059 +/- 0.262; P < 0.01). Bronchial alveolar lavage fluid (BALF) and lung tissue specimen analysis indicated that airway allergic inflammation was present.</p><p><b>CONCLUSIONS</b>The study demonstrates a dissociation between the bronchoconstrictor response and bronchial hyper-responsiveness and indicates that multiple ovalbumin exposures induces persistent bronchoconstriction with airway hypo-responsiveness despite airway allergic inflammation.</p>