Beta agonist regulation of sodium transport in fetal lung epithelium: Roles of cell volume, cytosolic chloride and protein tyrosine kinase

1) A beta agonist stimulated Na+ transport and decreased the intracellular Cl- concentration ([Cl-](c)) associated with cell shrinkage via an increase in cytosolic cAMP level by activating adenylate cyclase in rat fetal distal lung epithelial (FDLE) cells. 2) Lowering [Cl-](c) activated a 28-pS nonselective cation (NSC) channel by elongating the open time of the channel. 3) cAMP signals were converted to a protein tyrosine kinase (PTK)-mediated signal. 4) The PTK-mediated signal was involved in the cAMP-stimulated Na+ transport in rat FDLE cells.