[Effect of osmolality on ion transport in Guinea pig airway epithelial cells].
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).


OBJECTIVE
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 585 mOsm/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.
Hattori
Tomohiro
T
Division of Respiratory Medicine, Department of Medicine, Nihon University School of Medicine. tomohatt@med.nihon-u.ac.jp
Majima
Toru
T
Hashimoto
Shu
S
D000818:Animals; D004847:Epithelial Cells / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D017136:Ion Transport; D008297:Male; D009994:Osmolar Concentration; D014132:Trachea / Q000502:physiology*