Hypocapnia-induced contraction of porcine airway smooth muscle

K. S. Lindeman, T. L. Croxton, B. Lande, C. A. Hirshman

Research output: Contribution to journalArticle

Abstract

Hypocapnia constricts peripheral airways in vivo. This study investigated the role of airway smooth muscle in this phenomenon and the mechanism of hypocapnia-induced contraction in vitro. Isometric tension, intracellular pH (pH(i)) and intracellular free calcium concentration ([Ca2+](i)) were measured in porcine airway smooth muscles suspended in organ baths in the presence of 5% or 0% CO2. In tracheal strips precontracted with carbachol, hypocapnic challenge (0% CO2) produced increases in tension, pH(i), and [Ca2+](i). In bronchial rings or tracheal strips precontracted with carbachol, nifedipine administered between consecutive contractions attenuated responses to hypocapnia (75 ± 11% above carbachol-precontracted tension before nifedipine versus 39 ± 9% after nifedipine, n = 7 bronchial rings, p < .05). Neither indomethacin (5 μM), nordihydroguaiaretic acid (10 μM) nor phenidone (10 μM) significantly altered responses. These data suggest that enhanced Ca2+ influx through voltage-dependent Ca2+ channels of airway smooth muscle cells important in airways responses to hypocapnia.

Original languageEnglish (US)
Pages (from-to)1046-1052
Number of pages7
JournalEuropean Respiratory Journal
Volume12
Issue number5
DOIs
StatePublished - Nov 1998

Keywords

  • 27',7'-bis(2-carboxyethyl)-5(6)- carboxyfluorescein
  • Airway smooth muscle
  • Calcium channels
  • Fura-2
  • Intracellular free calcium ions
  • Intracellular pH

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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