Bradykinin stimulates Cl secretion and prostaglandin E2 release by canine tracheal epithelium

Bradykinin increased mean short-circuit current (Isc) when added either to the mucosal (KD = 1.1 nM; delta Imaxsc = 29.8 +/- 4.4 microA/cm2) or submucosal bath (KD = 108 nM; delta Imaxsc = 27.1 +/- 4.9 microA/cm2). Bumetanide or replacement of Cl reduced the maximal change in Isc. In paired tissues, the increase in net 36Cl flux toward the mucosa equaled the change in Isc. Net 22Na flux toward the submucosa was unchanged. Involvement of intramural nerves was ruled out because bradykinin-induced increases in Isc were not inhibited by phentolamine, propranolol, atropine, or tetrodotoxin. A direct action of bradykinin on the epithelium was also made probable by the autoradiographic demonstration of specific bradykinin binding sites. The antagonists of arachidonic acid metabolism, indomethacin and eicosa-5,8,11,14-tetraynoic acid, inhibited the increase in Isc induced by bradykinin. Finally, prostaglandin E2 release was significantly increased by submucosal addition of bradykinin, and this effect was abolished by pretreatment with indomethacin. We conclude that bradykinin stimulates Cl secretion in canine tracheal epithelium by increasing prostaglandin release.