2010 Volume 59 Issue 8 Pages 974-983
Background: Increased osmolality of the airway surface fluid due to water loss associated with hyperventilation is considered to be a cause of exercise-induced asthma (EIA). Aim: We investigated the influence of changes in osmolality on airway epithelial ion transport in guinea pigs. Methods: We explored from measuring open circuit potential difference in challenge with hypertonic saline or mannitol. Results: Diphenylamine-2-carboxylate (DPC), amiloride, and disodium cromoglycate (DSCG) prevented an increase of the potential difference (PD) after exposure of tracheal mucosa to 0.9-10.8% hypertonic saline solutions (HSSs) (p<0.05, p<0.01, and p<0.01, respectively on 1.8%). An increase of the PD was observed after a single dose of 1.8% hypertonic saline solution (HSS) was applied to the mucosa, but no increase was observed after a single exposure to a 585mOsm/kg aqueous mannitol solution (585AMS). The results remained the same when a Cl-free solution was used as the perfusate. The change of airway epithelial cell thickness was only suppressed significantly by DPC (p<0.01) after 1.8% HSS challenge. Conclusions: Not only the change of osmolality, but also changes of the Cl^- and Na^+ concentrations in airway surface fluid seem to have an important influence on the PD. cAMP-dependent Cl^- channel may have a role, and the same mechanism may provoke EIA.
