Abstract |
When SK-N-SH human neuroblastoma cells were exposed to nicotine (NIC) or KCl they showed a dose-dependent transient increase (2- to 4-fold) in intracellular Ca2+ concentration ([Ca2+])i as detected by quin-2 fluorescence, with half maximal effects (EC50) observed at 13 microM and 26 mM, respectively. Tubocurarine and 1-isodihydrohistrionicotoxin potently blocked the NIC-evoked (IC50 congruent to 1 microM and 0.3 microM, respectively), but not the high [K+]o-evoked [Ca2+]i accumulation. The KCl-induced response was inhibited by verapamil and diltiazem (IC50 = 1.4 and 10.9 microM, respectively). Tetrodotoxin (3 microM) and tetraethylammonium (10 microM) had no effect on [Ca2+]i accumulation induced by either agent. Increases in [Ca2+]i could be evoked sequentially by NIC and KCl in the same cells suggesting independent mechanisms of Ca2+ entry. In a Ca2+-free medium, no response to either KCl or NIC was observed. However, when Ca2+ ions were restored, [Ca2+]i accumulation was enhanced to the same extent as cells suspended in a Ca2+-containing buffer. Long-term (18 hr) pretreatment of SK-N-SH cells with pertussis (100 ng/ml) or cholera toxins (10 nM) had no effect on NIC or KCl-induced [Ca2+]i accumulation. Together, these data demonstrate the presence of NIC receptors and voltage-sensitive Ca2+ channels on SK-N-SH neuroblastoma cells, through which [Ca2+]i may be modulated.
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Authors | L Noronha-Blob, R Gover, J Baumgold |
Journal | Biochemical and biophysical research communications
(Biochem Biophys Res Commun)
Vol. 162
Issue 3
Pg. 1230-5
(Aug 15 1989)
ISSN: 0006-291X [Print] United States |
PMID | 2548492
(Publication Type: Journal Article)
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Chemical References |
- Aminoquinolines
- Amphibian Venoms
- Calcium Channel Blockers
- Calcium Channels
- Receptors, Nicotinic
- Nicotine
- Quin2-acetoxymethyl ester
- Calcium
- histrionicotoxin
- Tubocurarine
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Topics |
- Aminoquinolines
- Amphibian Venoms
(pharmacology)
- Calcium
(physiology)
- Calcium Channel Blockers
(pharmacology)
- Calcium Channels
(drug effects, physiology)
- Humans
- Membrane Potentials
- Neuroblastoma
- Nicotine
(pharmacology)
- Receptors, Nicotinic
(drug effects, physiology)
- Tubocurarine
(pharmacology)
- Tumor Cells, Cultured
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