title: The tracheal nonadrenergic noncholinergic inhibitory system during antigen challenge.
abstract: This study was undertaken to test the hypothesis that malfunction of the nonadrenergic noncholinergic inhibitory system (NANCIS) induces hyperreactive airways. Antigen sensitized guinea pigs were divided into four groups: (1) antigen challenge (n = 6), (2) 2 min oxyhemoglobin (HbO2) + antigen challenge (n = 5), (3) 27 min HbO2 + antigen challenge (n = 4), and (4) 2 min HbO2 + transmural stimulation (TS) + antigen challenge (n = 6). These animals were sensitized with ovalbumin 10 days before the study. In addition, 12 normal control animals without antigen sensitization were used for comparison. Under artificial ventilation, the anesthetized-paralyzed animals were hourly injected with atropine (0.2 mg/kg) and propranolol (1 mg/kg). Cervical segment of the trachea was converted to a closed tracheal pouch filled with Krebs solution containing also atropine (1 microM) and propranolol (3.5 microM). A change in the pouch pressure (Pp) reflected NANCIS TS- or antigen (5 micrograms) challenge-induced relaxation and/or constriction. HbO2 was used to inhibit NANCIS transmitter. There was no significant difference between normal and sensitized animals in the NANCIS TS-induced relaxation. Antigen challenge resulted in biphasic alteration in Pp, an initial increase and then a decrease after about 7 min. HbO2 pretreatment alone did not potentiate antigen-induced increase in Pp. HbO2 + TS, however, significantly abolished the late relaxation phase after antigen challenge.
authors.affiliation: Pharmacology and Toxicology Division, University of Kentucky College of Pharmacy, Lexington 40536.
authors.forename: W C
authors.initials: WC
authors.lastname: Ko
authors.forename: Y L
authors.initials: YL
authors.lastname: Lai
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D001285:Atropine / Q000494:pharmacology; D004558:Electric Stimulation; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006168:Guinea Pigs; D007114:Immunization; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects; D010047:Ovalbumin / Q000276:immunology; D010108:Oxyhemoglobins / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000276:immunology / Q000294:innervation*; D014135:Tracheal Stenosis / Q000139:chemically induced*
chemical_list: D000941:Antigens; D010108:Oxyhemoglobins; D001285:Atropine; D010047:Ovalbumin; D011433:Propranolol; D005703:Gallamine Triethiodide