title: Histamine Applied Topically to the Nasal Mucosa Increases the Transmucosal Nitrous Oxide Exchange for the Middle Ear.
abstract: OBJECTIVE
  Determine if the middle ear transmucosal nitrous oxide (N2O) exchange rate is affected by nasal inflammation caused by topical application of histamine.
  
  
  METHODS
  In a randomized, double-blind, crossover study, 20 adults were challenged intranasally with histamine (5 mg) and placebo on separate occasions. At each session, the subjects were fitted with a non-rebreathing mask and breathed room air for 20 minutes, 50% N2O:50% O2for 20 minutes, and 100% O2for 10 minutes. Throughout, heart rate, blood pressure, and blood O2saturation were monitored, and bilateral middle ear pressure was recorded by tympanometry every minute. The primary outcome measure was the slope of the middle ear pressure-time function for the 50% N2O:50% O2breathing period, which is a measure of the transmucosal N2O exchange-constant. The effects of challenge substance, session, and period on the measured vital signs and of treatment, session, ear disease history, and test ear on the pressure-time slopes were evaluated using repeated measures ANOVAs.
  
  
  RESULTS
  The post-challenge total symptom score and the slope of the middle ear pressure-time function were greater after histamine when compared to placebo challenge. Of the signs, only heart rate was affected, responding to challenge substance and study period.
  
  
  CONCLUSIONS
  The transmucosal N2O exchange rate for the middle ear is increased during inflammation caused by nasal histamine exposure.
authors.affiliation: 1 Department of Otolaryngology, School of Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Miriam S
authors.initials: MS
authors.lastname: Teixeira
authors.affiliation: 1 Department of Otolaryngology, School of Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.|2 Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Cuneyt M
authors.initials: CM
authors.lastname: Alper
authors.affiliation: 3 Division of Pediatric Dentistry, School of Dental Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.|4 Department of Dentistry, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Martin
authors.affiliation: 1 Department of Otolaryngology, School of Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Selma
authors.initials: S
authors.lastname: Cetin
authors.affiliation: 1 Department of Otolaryngology, School of Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Jenna A
authors.initials: JA
authors.lastname: El-Wagaa
authors.affiliation: 1 Department of Otolaryngology, School of Medicine of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Doyle
mesh_terms: D000158:Acoustic Impedance Tests; D000281:Administration, Intranasal; D000287:Administration, Topical; D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004432:Ear, Middle / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D064368:Healthy Volunteers; D006632:Histamine / Q000494:pharmacology*; D017442:Histamine Agonists / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000187:drug effects* / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism*; D012039:Regional Blood Flow; D055815:Young Adult
chemical_list: D017442:Histamine Agonists; D006632:Histamine; D009609:Nitrous Oxide
keywords: blood flow; gas exchange; histamine; middle ear; nasal challenge; nitrous oxide