Role of tachykinins in airway responses to ozone in rats

Toru Takebayashi, Joseph Abraham, G. G.Krishna Murthy, Craig Lilly, Ian Rodger, Stephanie A. Shore

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16 Citations (Scopus)

Abstract

Previous studies that used neonatal capsaicin (Cap) treatment to ablate C fibers indicate that C fibers act to inhibit lung damage and airway hyperresponsiveness after ozone (O3) exposure in rats. The purpose of this study was to determine 1) the role of tachykinins in these protective effects and 2) whether differences in minute ventilation (V̇E) during O3 exposure might account for the effect of Cap. In the first study, male Sprague-Dawley rats were exposed to 1 part/million O3 or air for 3 h. Four hours later, a bronchoalveolar lavage (BAL) was performed or airway responsiveness was measured. Rats were treated with CP-99994 and SR-48968, selective neurokinin- 1-and -2-receptor antagonists, respectively, or with vehicle (Veh). O3 caused an increase in the number of neutrophils recovered from BAL fluid in both the Veh-treated and tachykinin-receptor antagonist (TKRA)-treated rats, but the number of neutrophils was approximately twofold greater in the TKRA- treated rats. In contrast, TKRA treatment had no effect on baseline pulmonary mechanics or airway responsiveness. After O3 exposure, the number of neutrophils in BAL fluid was also greater in Cap- than in Veh-treated rats. O3 reduced V̇E in both Veh- and Cap-treated rats, but the response was greater (reduction of 44.7 ± 3.7 vs. 27.8 ± 6.8%) and occurred earlier (10 vs. 70 min) in Cap- than in Veh-treated rats (P < 0.02). These results suggest that tachykinins mediate protective effects of C fibers against O3- induced lung inflammation. The results also indicate that the more pronounced effect of O3 on BAL neutrophils in Cap-treated rats is not the result of a greater inhaled dose of O3 resulting from greater V̇E.

Original languageEnglish
Pages (from-to)442-450
Number of pages9
JournalJournal of Applied Physiology
Volume85
Issue number2
Publication statusPublished - 1998 Aug 1
Externally publishedYes

Keywords

  • Airway responsiveness
  • Breathing frequency
  • Bronchoalveolar lavage
  • Bronchoconstriction
  • C fibers
  • CP-99994
  • Methacholine
  • SR-48968
  • Tidal volume
  • Ventilation

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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  • Cite this

    Takebayashi, T., Abraham, J., Murthy, G. G. K., Lilly, C., Rodger, I., & Shore, S. A. (1998). Role of tachykinins in airway responses to ozone in rats. Journal of Applied Physiology, 85(2), 442-450.