Antigen- and histamine H1 receptor-mediated relaxation of guinea pig isolated trachea

Bradley J. Undem, Lawrence M. Lichtenstein, G. Kenneth Adams

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We have investigated the effect of challenge in vitro with specific antigen (ovalbumin) on actively sensitized guinea pig tracheal rings maximally precontracted with methacholine. Ovalbumin relaxed the trachea in a concentration-dependent fashion with a negative log ED50 value (g/ml) of 7.0 ± 0.3. In 16 experiments, the maximum antigen-induced relaxation was 26 ± 3% of complete relaxation induced by 10-3 M papaverine (x ± S.E.M.). Antigen-induced relaxations were selectively antagonized by diphenhydramine. Similarly, histamine relaxed the precontracted tracheal smooth muscle with a negative log molar ED50 of about 4.5 and a maximum effect of 28 ± 3% (x ± S.E.M., n = 20). Histamine-induced relaxations were antagonized by diphenhydramine and mepyramine but were unaffected by cimetidine, metiamide or burimamide. Dimaprit (10-5-10-3 M) did not relax the precontracted trachea. Indomethacin significantly inhibited relaxation induced by both antigen and histamine. In contrast, phenidone or 5,8,11,14-eicosatetraynoic acid had no effect on relaxation but reversed the inhibition by indomethacin. Neither propranolol (10-6 M) nor removing the tracheal epithelium inhibited histamine-induced relaxation. These results suggest that antigen-induced relaxation of guinea pig tracheal smooth muscle involves activation of histamine H1 receptors and can occur independently of arachidonic acid metabolism, β-adrenoceptor activation or airway epithelium.

Original languageEnglish (US)
Pages (from-to)297-305
Number of pages9
JournalEuropean Journal of Pharmacology
Issue number3
StatePublished - Jul 23 1987


  • (Immediate hypersensitivity)
  • Anaphylaxis
  • Antigen-induced contraction
  • Histamine
  • Histamine antagonists
  • Smooth muscle (airway)

ASJC Scopus subject areas

  • Pharmacology


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