Role of cyclic AMP in regulation of chloride secretion by canine tracheal mucosa.

Cyclic adenosine monophosphate (cyclic AMP) mediates the action of many hormones, and it affects ion transport in several different epithelia. The effect of the analogue dibutyryl cyclic AMP was tested in canine tracheal epithelium in vitro under short-circuit conditions. This agent raised short-circuit current and electrical conductance. Dibutyryl cyclic AMP at 1 mM concentration added to the submucosal bath increased net Cl secretion from 1.74 +/- 0.40 to 2.72 +/- 0.34 mu eq/cm2 . h (mean +/- SE, n = 6). Net Na absorption was slightly reduced. Dibutyryl cyclic AMP and theophylline decreased mannitol flux, suggesting that cyclic AMP acts on Cl transport by increasing its flow through cellular rather than through paracellular pathways. Epinephrine, which also stimulates Cl secretion, causes significant elevation in cyclic AMP in epithelial cells scraped from tracheal mucosa. Data suggest that cellular concentrations of cyclic AMP play an important role in the regulation of Cl transport by tracheal mucosa.