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Calcium influx mediated by nicotinic receptors and voltage sensitive calcium channels in SK-N-SH human neuroblastoma cells.

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.
AuthorsL Noronha-Blob, R Gover, J Baumgold
JournalBiochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 162 Issue 3 Pg. 1230-5 (Aug 15 1989) ISSN: 0006-291X [Print] United States
PMID2548492 (Publication Type: Journal Article)
Chemical References
  • Aminoquinolines
  • Amphibian Venoms
  • Calcium Channel Blockers
  • Calcium Channels
  • Receptors, Nicotinic
  • Nicotine
  • Quin2-acetoxymethyl ester
  • Calcium
  • histrionicotoxin
  • Tubocurarine
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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