LAN-1: a human neuroblastoma cell line with M1 and M3 muscarinic receptor subtypes coupled to intracellular Ca2+ elevation and lacking Ca2+ channels activated by membrane depolarization.
The LAN-1 clone, a cell line derived from a human neuroblastoma, possesses muscarinic receptors. The stimulation of these receptors with increasing concentrations of carbachol (CCh; 1-1,000 microM) caused a dose-dependent increase of the intracellular free Ca2+ concentration ([Ca2+]i). This increase was characterized by an early peak phase (10 s) and a late plateau phase. The removal of extracellular Ca2+ reduced the magnitude of the peak phase to approximately 70% but completely abolished the plateau phase. The muscarinic-activated Ca2+ channel was gadolinium (Gd3+) blockade and nimodipine and omega-conotoxin insensitive. In addition, membrane depolarization did not cause any increase in [Ca2+]i. The CCh-induced [Ca2+]i elevation was concentration-dependently inhibited by pirenzepine and 4-diphenylacetoxy-N-methylpiperidine methiodide, two rather selective antagonists of M1 and M3 muscarinic receptor subtypes, respectively, whereas methoctramine, an M2 antagonist, was ineffective. The coupling of M1 and M3 receptor activation with [Ca2+]i elevation does not seem to be mediated by a pertussis toxin-sensitive guanine nucleotide-binding protein or by the diacylglycerol-protein kinase C system. The mobilization of [Ca2+]i elicited by M1 and M3 muscarinic receptor stimulation seems to be dependent on an inositol trisphosphate-sensitive intracellular store. In addition, ryanodine did not prevent CCh-induced [Ca2+]i mobilization, and, finally, LAN-1 cells appear to lack caffeine-sensitive Ca2+ stores, because the methylxanthine was unable to elicit intracellular Ca2+ mobilization, under basal conditions, after a subthreshold concentration of CCh (0.3 microM), or after thapsigargin.
Fatatis
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A
Department of Science of Human Communication, 2nd School of Medicine, University of Naples Federico II, Italy.
Bassi
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A
Monsurrò
M R
MR
Sorrentino
G
G
Mita
G D
GD
Di Renzo
G F
GF
Annunziato
L
L
D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D004594:Electrophysiology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism; D018727:Muscarinic Antagonists; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D009994:Osmolar Concentration; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D037342:Pertussis Toxin; D011493:Protein Kinase C; D002118:Calcium