Agonist-stimulated calcium decreases in ovine ciliated airway epithelial cells: Role of mitochondria

Matthias A Salathe, Pedro I. Ivonnet, Thomas Lieb, Richard J. Bookman

Research output: Contribution to journalArticle

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Abstract

1. In ovine ciliated tracheal epithelial cells, acetylcholine (ACh) activates signal transduction pathways that not only transiently increase cytoplasmic Ca2+ ([Ca2+]1) but also actively lower [Ca2+]1. The pathway for decreasing [Ca2+]1 is clearly revealed after depletion of intracellular Ca2+ stores by thapsigargin (Tg), 2,5-di-(tert-butyl)-1,4-benzohydroquinone or NiCl2. Measurements with microinjected fura-2 excluded a [Ca2+] measurement artefact. 2. A four-compartment model to simulate calcium transients in non-excitable cells (consisting of a plasma membrane Ca2+ pump and channel; Ca2+ store with pump and channel; and cytosolic Ca2+ buffer) could not account for the observed [Ca2+]1 decrease. We therefore explored, by simulation and experimentation, several different mechanisms that could account for it. 3. The ACh-stimulated [Ca2+]1 decrease was not due to an inhibition of Ca2+ influx (Ca2+ channel blockers or absence of extracellular calcium had no effect), activation of a plasma membrane Ca2+-ATPase (two inhibitors, vanadate (30 mM) and lanthanum (10 mM), had no effect) or inhibition of the Na+-Ca2+ exchanger (replacing extracellular Na+ with N-methylglucamine had no effect). 4. The application of mitochondrial uncouplers (5 μM CCCP or 5 μM FCCP), eliminated the ACh-induced [Ca2+]1 decrease. Addition of CCCP at the nadir of the decrease restored intracellular calcium levels of Tg-treated cells to baseline faster than controls not exposed to mitochondrial uncouplers. CCCP application to naïve cells did not block the ACh-induced transient increase in [Ca2+]1. 5. These data suggest that ACh-induced [Ca2+]i decreases in ciliated cells are caused by stimulated Ca2+ uptake into mitochondria.

Original languageEnglish
Pages (from-to)13-26
Number of pages14
JournalJournal of Physiology
Volume531
Issue number1
DOIs
StatePublished - Feb 15 2001

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Acetylcholine
Carbonyl Cyanide m-Chlorophenyl Hydrazone
Sheep
Mitochondria
Epithelial Cells
Calcium
Thapsigargin
Cell Membrane
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
Meglumine
Lanthanum
Vanadates
Calcium-Transporting ATPases
Fura-2
Artifacts
Signal Transduction
Buffers

ASJC Scopus subject areas

  • Physiology

Cite this

Agonist-stimulated calcium decreases in ovine ciliated airway epithelial cells : Role of mitochondria. / Salathe, Matthias A; Ivonnet, Pedro I.; Lieb, Thomas; Bookman, Richard J.

In: Journal of Physiology, Vol. 531, No. 1, 15.02.2001, p. 13-26.

Research output: Contribution to journalArticle

Salathe, Matthias A ; Ivonnet, Pedro I. ; Lieb, Thomas ; Bookman, Richard J. / Agonist-stimulated calcium decreases in ovine ciliated airway epithelial cells : Role of mitochondria. In: Journal of Physiology. 2001 ; Vol. 531, No. 1. pp. 13-26.
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