title: The TRPV1 receptor agonist capsaicin is an ineffective bronchoprovocant in an experimental model of feline asthma.
abstract: OBJECTIVE
  Airway hyper-responsiveness (AHR), a key feature of feline asthma, can be measured using bronchoprovocation testing. Limitations of both direct and indirect bronchoprovocants evaluated to date in experimental feline asthma have led to a search for a more specific indirect bronchoprovocant (ie, one which relies on existing inflammatory cells or activated neural pathways in diseased but not healthy airways). We hypothesized that capsaicin, a transient receptor potential cation channel subfamily V member 1 agonist, would lead to dose-responsive increases in airway resistance as measured by ventilator-acquired pulmonary mechanics in experimentally asthmatic cats.
  
  
  METHODS
  Five cats induced to have asthma using Bermuda grass allergen (BGA) were studied. Twenty-four hours after aerosol challenge of BGA, cats were anesthetized and underwent neuromuscular blockade for ventilator-acquired pulmonary mechanics. Cats were monitored with pulse oximetry for hemoglobin desaturation. Parameters recorded on a breath-by-breath basis on the ventilator included airway resistance (Raw) and compliance. Saline at baseline and 10-fold increasing concentrations of capsaicin (0.4-4000.0 µM) were aerosolized for 30 s and data collected for 4 mins between doses. The intended endpoint of the study was a doubling in baseline airway resistance, halving of compliance or oxygen desaturation <75%.
  
  
  RESULTS
  All cats completed the trial, reaching the highest dose of capsaicin without reaching any of the aforementioned endpoints. No biologically significant alteration in any other pulmonary mechanics parameter was noted.
  
  
  CONCLUSIONS
  Capsaicin does not appear to be an effective bronchoprovocant in a feline asthma model.
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Grobman
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: Stacy
authors.initials: S
authors.lastname: Krumme
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Dodam
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA reineroc@missouri.edu.
authors.forename: Carol R
authors.initials: CR
authors.lastname: Reinero
mesh_terms: D000403:Airway Resistance / Q000187:drug effects; D000485:Allergens / Q000276:immunology; D000818:Animals; D001249:Asthma / Q000662:veterinary*; D001985:Bronchial Provocation Tests / Q000662:veterinary*; D002211:Capsaicin / Q000378:metabolism*; D002371:Cat Diseases / Q000175:diagnosis* / Q000276:immunology*; D002415:Cats; D031744:Cynodon; D023421:Models, Animal; D050916:TRPV Cation Channels / Q000378:metabolism*
chemical_list: D000485:Allergens; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D002211:Capsaicin