Esophageal stimulation by hydrochloric acid causes neurogenic inflammation in the airways in guinea pigs

Hamamoto, Junji, Hirotsugu Kohrogi, Osamu Kawano,Hajime Iwagoe, Kazuhiko Fujii, Nahomi Hirata, and Masayuki Ando.Esophageal stimulation by hydrochloric acid causes neurogenicinflammation in the airways in guinea pigs. J. Appl.Physiol. 82(3): 738-745, 1997.Toinvestigate whether tachykinins are released in the airways in responseto stimulation of the esophagus, we studied the airway plasmaextravasation induced by intraesophageal HCl in the presence or absenceof neutral endopeptidase inhibitor phosphoramidon and NK₁-receptor antagonist FK-888 inanesthetized guinea pigs. The airway plasma leakage wasevaluated by measuring extravasated Evans blue dye in the animalspretreated with propranolol and atropine. Infusion of 1 N HCl into theesophagus significantly increased plasma extravasation in the trachea.Phosphoramidon significantly potentiated plasma extravasation in thetrachea and main bronchi, whereas FK-888 significantly inhibited that extravasation in a dose-related manner. In the capsaicin-treated animals, airway plasma extravasation was completely inhibited even inthe presence of phosphoramidon. Tracheal plasma extravasation potentiated by phosphoramidon was significantly inhibited in the bilateral vagotomized animals. These results suggest that1) tachykinin-like substances arereleased to cause plasma extravasation in the airways as a result ofintraesophageal HCl stimulation and2) there are neural pathwayscommunicating between the esophagus and airways, including the vagusnerve.