In the present study, we describe a novel three-dimensional airway epitheli
al explant preparation and demonstrate its use for ion transport studies by
electrophysiological technique. Suspension cultures of sheets of epithelia
l cells released by protease treatment from cystic fibrosis (CF) and non-CF
nasal polyps developed free-floating, monolayered epithelial spheres, with
the apical, ciliated cell membrane facing the bath and the basolateral cel
l membrane pointing toward a fluid-filled lumen. Microelectrode impalement
of both non-CF and CF spheroids revealed lumen-positive transepithelial ele
ctrical potential differences (PDs) that were inhibited by amiloride, indic
ating that the spheroids were inflated due to amiloride-sensitive Na+ absor
ption followed by water. Transformation to a Cl- secretory state was achiev
ed by addition of ATP to the bath, leading to the development of a diphenyl
amine-2-carboxylate-sensitive PD. A cAMP-induced increase in PD was seen in
non-CF spheroids only. In response to hydrocortisone treatment, Na+ transp
ort reflected by amiloride-sensitive PD increased and more so in CF than in
non-CF spheres. We concluded that this preparation is a useful model for t
he airway surface epithelium and is suitable for studies of transport mecha
nisms and regulation.