Title : Mouse beta-TC6 insulinoma cells: high expression of functional alpha3beta4 nicotinic receptors mediating membrane potential, intracellular calcium, and insulin release - Ohtani_2006_Mol.Pharmacol_69_899 |
Author(s) : Ohtani M , Oka T , Badyuk M , Xiao Y , Kellar KJ , Daly JW |
Ref : Molecular Pharmacology , 69 :899 , 2006 |
Abstract :
Nicotine elicited membrane depolarization, elevation of intracellular calcium, rubidium efflux, and release of insulin from mouse beta-TC6 insulinoma cells. Such responses were blocked by the nicotinic antagonist mecamylamine but not by the muscarinic antagonist atropine. Neither the selective alpha4beta2 antagonist dihydro-beta-erythroidine nor the selective alpha7 antagonist methyllycaconitine significantly blocked the nicotine-elicited depolarization or the calcium response. The elevation of intracellular calcium did not occur in calcium-free media, indicating that the increase in intracellular calcium was due to the influx of calcium. The rank order of potency for nicotinic agonists was as follows: epibatidine > nicotine = 3-(azetidinylmethoxy)pyridine (A-85380), cytisine, dimethylphenylpiperazinium (DMPP). Cytisine and DMPP seemed to be partial agonists. The density of nicotinic receptors measured by [3H]epibatidine binding was 7-fold higher in membranes from beta-TC6 cells than in rat brain membranes. No binding of 125I-A-85380 was detected, indicating the absence of beta2-containing receptors. Reverse transcription-polymerase chain reaction analyses indicated the presence of mRNA for alpha3 and alpha4 subunits and beta2 and beta4 subunits in beta-TC6 cells. The binding and functional data suggest that the major nicotinic receptor is composed of alpha3 and beta4 subunits. The beta-TC6 cells thus provide a model system for pharmacological study of such nicotinic receptors. |
PubMedSearch : Ohtani_2006_Mol.Pharmacol_69_899 |
PubMedID: 16332988 |
Ohtani M, Oka T, Badyuk M, Xiao Y, Kellar KJ, Daly JW (2006)
Mouse beta-TC6 insulinoma cells: high expression of functional alpha3beta4 nicotinic receptors mediating membrane potential, intracellular calcium, and insulin release
Molecular Pharmacology
69 :899
Ohtani M, Oka T, Badyuk M, Xiao Y, Kellar KJ, Daly JW (2006)
Molecular Pharmacology
69 :899