Tracheal narrowing during histamine-induced bronchoconstriction

H. Baier, J. L. Rodriguez, A. Chediak, A. Wanner

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

To determine whether tracheal narrowing accompanies histamine-induced bronchoconstriction and whether a cholinergic reflex is involved in the tracheal and bronchial responses, we determined specific pulmonary resistance between the carina and the pleura (sRL) and tracheal volume (Vtr) with an indicator-dilution technique in conscious sheep. Immediately postdelivery of histamine aerosol (7.5 mg histamine base) mean sRL increased by 223% (P < 0.05), and mean Vtr decreased by 25% (P < 0.05). The duration of the changes was similar, with a return to base-line values within 60 min. With increasing doses of histamine up to 30 mg, there was a corresponding increase in mean sRL, whereas the maximum effect on Vtr was already reached after 7.5 mg of histamine. Atropine (0.2 mg/kg iv) increased mean Vtr by 77% (P < 0.05) and blunted the histamine effects on sRL, whereas the histamine effects on Vtr were abolished. Intravenous histamine or carbachol aerosol had similar effects on sRL and Vtr. We conclude that in concious sheep 1) histamine produces both tracheal and bronchial constriction with a similar time course 2) there is a baseline vagal tone in the trachea and not the bronchi, 3) the cholinergic reflex component of histamine-induced constriction is greater in the trachea than the bronchi, and 4) this difference between the trachea and bronchi is not due to differential aerosol deposition or cholinergic responsiveness.

Original languageEnglish (US)
Pages (from-to)1223-1228
Number of pages6
JournalJournal of applied physiology
Volume64
Issue number3
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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