Mechanical modulation of pressure-volume characteristics of contracted canine airways in vitro

S. J. Gunst, J. Q. Stropp, J. Service

Research output: Contribution to journalArticle

80 Scopus citations

Abstract

In normal humans and dogs, the airways do not constrict to closure even when maximally stimulated. However, airway closure can be produced in isolated canine lobes and bronchial segments that are stimulated with maximal concentrations of bronchoconstrictors. These observations suggest that under normal conditions, physiological mechanisms to limit bronchoconstriction exist in vivo. In this investigation, we evaluated how mechanical factors that influence airway smooth muscle contractility contribute to the modulation of the pressure-volume characteristics of contracted canine intra-parenchymal airways in vitro. Our results demonstrated that maximal and even submaximal contractile stimuli can produce airway closure in bronchi that are allowed to contract under isobaric conditions. However, the effectiveness of bronchoconstrictors is significantly reduced when the airways are subjected to tidal volume oscillations during contraction. In addition, airways contracted isovolumetrically at low volumes exhibit a markedly reduced sensitivity to submaximal concentrations of acetylcholine. This may limit bronchoconstriction at low lung volumes and transpulmonary pressures where the effectiveness of parenchymal stress in keeping the airways open is reduced. Together these factors could provide a mechanism by which bronchoconstriction is limited to low levels of airway resistance under normal conditions in vivo.

Original languageEnglish (US)
Pages (from-to)2223-2229
Number of pages7
JournalJournal of Applied Physiology
Volume68
Issue number5
StatePublished - Jan 1 1990

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Keywords

  • airway closure
  • airway mechanics
  • airway reactivity
  • airway resistance
  • bronchi
  • length-tension properties
  • lung mechanics

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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