Cystic fibrosis factors: effect of serum on the secretory response of dispersed rat submandibular cells.

The action of serum from cystic fibrosis patients on the intracellular maintenance, efflux, and uptake of potassium ions in dispersed acinar cells from the rat submandibular gland, a seromucous salivary gland, was investigated in an attempt to demonstrate the presence of factors affecting ion-coupled secretion. No effects specific to cystic fibrosis serum were demonstrated upon the following parameters of potassium transport: (1) maximal stimulation of K+ efflux by the cholinergic agonists carbamylcholine; (2) the dose-response curve of K+ efflux in response to carbamylcholine; (3) re-entry of K+ into cells after carbamylcholine stimulation; (4) the maintenance of K+ in the absence of added effectors. No differences were observed between cells pretreated with serum and cells to which serum was added at the time of cholinergic stimulation of secretion. At high concentrations, serum from both normal individuals and those with cystic fibrosis severely damaged the cells in a rapid and irreversible fashion. K+ transport has a direct, closely coupled, specific relationship to secretory activity and is Ca++ dependent in this system. From these observations, we conclude that serum from individuals with cystic fibrosis does not contain chemical compounds which specifically alter the major components of ion-coupling to secretion or the secretory process itself in salivary gland acinar cells.