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 language | English |
|---|---|
| Pages (from-to) | 13-26 |
| Number of pages | 14 |
| Journal | Journal of Physiology |
| Volume | 531 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 15 2001 |
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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 journal › Article
}
TY - JOUR
T1 - Agonist-stimulated calcium decreases in ovine ciliated airway epithelial cells
T2 - Role of mitochondria
AU - Salathe, Matthias A
AU - Ivonnet, Pedro I.
AU - Lieb, Thomas
AU - Bookman, Richard J.
PY - 2001/2/15
Y1 - 2001/2/15
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0035865219&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035865219&partnerID=8YFLogxK
U2 - 10.1111/j.1469-7793.2001.0013j.x
DO - 10.1111/j.1469-7793.2001.0013j.x
M3 - Article
C2 - 11179388
AN - SCOPUS:0035865219
VL - 531
SP - 13
EP - 26
JO - Journal of Physiology
JF - Journal of Physiology
SN - 0022-3751
IS - 1
ER -