Effect of terbutaline on movement of Cl- and Na+ across the trachea of the dog in vitro.

The epithelium of canine trachea maintains a transepithelial potential difference (lumen negative relative to submucosa) by active transport of Cl- toward the lumen and of Na+ away from the lumen. This study examined the effects of terbutaline (a beta-adrenergic agonist) on short-circuit current, potential difference, electrical conductance, and fluxes of 36Cl and 24Na measured across pieces of canine trachea mounted in Ussing-type chambers. In short-circuited tissues, 10(-5) M terbutaline increased unidirectional Cl- flux toward the lumen from 4.78 +/- 1.12 (mean +/- SEM) to 6.28 +/- 1.06 muEq/cm2.h. The other measured fluxes did not change significantly. Increases in unidirectional Cl- flux toward the lumen were related to terbutaline concentration (range, 10(-7) to 10(-5) M); 10(-6) M propranolol prevented or decreased these effects. These studies suggest that terbutaline acts via beta-adrenergic receptors to increase active transport of Cl- toward the lumen.