title: Increased responsiveness to 5-hydroxytryptamine after antigenic challenge is inhibited by nifedipine and niflumic acid in rat trachea in vitro.
abstract: Antigenic challenge often induces hyperreactivity in asthmatic airway, although the precise mechanism(s) underlying this increased responsiveness is not entirely known. Tracheae obtained from ovalbumin (OVA)-sensitized saline- or OVA-challenged rats were placed in 10 mL bath chambers for isometric recording of 5-hydroxytryptamine (5-HT)-induced contractions. 5-Hydroxytryptamine induced a stronger contraction compared with control in antigen-challenged trachea under normal or Ca2+-free conditions. In tracheae pretreated with the L-type Ca2+ channel blocker nifedipine (10(-6) mol/L) or the Ca2+-activated Cl- channel blocker niflumic acid (10(-4) mol/L), this hyperresponsiveness was not developed in either normal or Ca2+-free medium. The increased contractile response to 5-HT in allergic rat isolated trachea may be related to a greater ionic (Ca2+ and Cl-) channel involvement.
authors.affiliation: Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil.
authors.forename: Carlos Tiago Martins
authors.initials: CT
authors.lastname: Moura
authors.forename: Fernanda Carvalho
authors.initials: FC
authors.lastname: Bezerra
authors.forename: Isabelle Maciel
authors.initials: IM
authors.lastname: de Moraes
authors.forename: Pedro Jorge Caldas
authors.initials: PJ
authors.lastname: Magalhães
authors.forename: Francisco Ruy
authors.initials: FR
authors.lastname: Capaz
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D000941:Antigens / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology*; D009544:Niflumic Acid / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000941:Antigens; D002121:Calcium Channel Blockers; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D009544:Niflumic Acid; D009543:Nifedipine; D002118:Calcium