ION-TRANSPORT IN CULTURED PIG TRACHEAL SUBMUCOSAL GLAND ACINAR-CELLS STUDIED BY X-RAY-MICROANALYSIS

The submucosal glands of the airway may contribute more to the airway fluid than the surface epithelium. The cellular mechanisms underlying the regulation of electrolyte and water transport in airway submucosal glands are, however, still poorly understood, Therefore, we attempted to establish a cell culture system to facilitate study of this regula tion, Acinar cells were isolated by enzymatic disaggregation from pig tracheal submucosal tissue and cultured on a plastic substrate coated with human placental collagen, The fine structure of the cells in conf luent culture was studied by conventional transmission electron micros copy, The elemental content in resting cells and stimulated cells grow n on a permeable substrate was studied by X-ray microanalysis, The cul tured cells retained structural characteristics (microvilli, secretory granules and desmosomes) of in situ epithelia. The total intracellula r Cl and K concentrations significantly decreased after stimulation wi th the cholinergic agonist acetylcholine, the predominantly alpha-adre nergic agonist norepinephrine, or the beta-adrenergic agonist isoprote renol, Both ionomycin and 8-bromoadenosine 3':5'-cyclic monophosphate (8-bromo-cAMP) caused a marked decrease of the intracellular Cl, K and Na concentrations, Cl-secretion induced by acetylcholine was inhibite d by Cl-channel blockers anthracene-9-carboxylic acid and 5-nitro-2(3- phenylpropyl-amino)-benzoic acid (NPPB), but Cl-efflux induced by 8-br omo-cAMP was blocked only by NPPB, The intracellular Cl and Na content significantly increased and the cellular K content markedly decreased after treatment with ouabain, These results indicate that the culture d acinar cells maintained the structural and functional characteristic s of in situ tissue and that this system is suitable for studying aspe cts of ion and water transport by the airway submucosal gland cells.