Systemic pilocarpine increases deposition of and decreases responsiveness to inhaled carbachol in sheep

L. Garcia, C. S. Kim, R. Forteza, A. Wanner

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The purpose of this study was to determine whether excessive airway secretions could serve as a barrier function against inhaled particulate matter. To increase airway secretions, six conscious sheep were treated with pilocarpine (0.8 mg/kg iv). Pilocarpine increased pulmonary resistance (RL) and total aerosol deposition within five breaths (AD5) as determined by the rebreathing of an inert monodisperse aerosol. When RL had returned to baseline, AD5 remained elevated [21 ± 2% (SE), P < 0.05] and tracheal secretions were increased (237 ± 77%, P < 0.05) above the values before pilocarpine administration. A carbachol aerosol dose-response curve was carried out at this time and compared with a control carbachol dose-response curve by calculating the dose of carbachol required to increase RL by 400% (PD400). Mean PD400 was increased postpilocarpine by 53 ± 18 (P < 0.05) and 85 ± 25% (P < 0.05) when normalized for increased aerosol deposition. Thus, pilocarpine decreased airway responsiveness to inhaled carbachol despite increasing aerosol deposition. The pilocarpine-induced airway hyporesponsiveness to inhaled carbachol is consistent with the hypothesis that excessive secretions have a protective role in the airways.

Original languageEnglish (US)
Pages (from-to)2343-2348
Number of pages6
JournalJournal of applied physiology
Volume73
Issue number6
DOIs
StatePublished - 1992

Keywords

  • aerosol deposition
  • bronchial provocation
  • bronchoconstriction
  • mucus

ASJC Scopus subject areas

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

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