Abstract |
Ca2+ entry following Ca2+ store depletion was examined in the human neuroblastoma cell line, SH-SY5Y, by measuring the concentration of intracellular free Ca2+ ([Ca2+]i) with fura-2. Application of the muscarinic agonist oxotremorine-M (oxo-M) caused an increase in [Ca2+]i. This consisted of a peak, mediated by release of Ca2+ from internal stores followed by a sustained plateau, mediated by Ca2+ entry across the plasma membrane. The Ca2+ entry resulted from depletion of intracellular Ca2+ stores This pathway was further characterized in the presence of thapsigargin, an inhibitor of the Ca2+ ATPase involved in replenishing IP3-sensitive stores. Stores were first depleted with oxo-M and thapsigargin in the absence of extracellular Ca2+. After washout of oxo-M, subsequent exposure to Ca2+ evoked reproducible increases in [Ca2+]i. Application of oxo-M plus Ca2+ had little effect on the increases in [Ca2+]i, indicating that in SH-SY5Y cells, agonist-dependent pathways contribute little to Ca2+ entry following store depletion. Mn2+, Sr2+ and Ba2+ were permeable through this pathway. Mn2+ and Ba2+ also showed slight permeability in the absence of store depletion. Ca2+ entry following store depletion was blocked by La3+ (IC50 = 75 nM) and by SKF 96365. La3+ blocked Mn2+ entry through the pathway activated by store depletion but did not affect basal Mn2+ permeability. These results indicate that SH-SY5Y neuroblastoma cells have an agonist-independent Ca2+ entry pathway activated by store depletion.
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Authors | T J Grudt, M M Usowicz, G Henderson |
Journal | Brain research. Molecular brain research
(Brain Res Mol Brain Res)
Vol. 36
Issue 1
Pg. 93-100
(Feb 1996)
ISSN: 0169-328X [Print] Netherlands |
PMID | 9011769
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Imidazoles
- Muscarinic Agonists
- Barium
- Manganese
- Oxotremorine
- oxotremorine M
- Thapsigargin
- Lanthanum
- Inositol 1,4,5-Trisphosphate
- 1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
- Calcium
- Strontium
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Topics |
- Barium
(pharmacokinetics)
- Calcium
(metabolism)
- Cell Membrane Permeability
- Imidazoles
(pharmacology)
- Inositol 1,4,5-Trisphosphate
(metabolism)
- Lanthanum
(pharmacology)
- Manganese
(pharmacokinetics)
- Muscarinic Agonists
(pharmacology)
- Neuroblastoma
- Neurons
(metabolism)
- Oxotremorine
(analogs & derivatives, pharmacology)
- Strontium
(pharmacokinetics)
- Thapsigargin
(pharmacology)
- Tumor Cells, Cultured
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