Pharmacological characterization of cholinergic receptors in a human neuroblastoma cell line.
A human neuroblastoma cell line, IMR32, has been characterized as far as morphology, membrane receptors for neurotransmitters, and uptake and release of [3H]3,4-dihydroxyphenylethylamine ([3H]dopamine). These cells expressed at their surface both nicotinic and muscarinic cholinergic receptors, revealed by [125I]alpha-bungarotoxin and [3H]quinuclidinylbenzilate ([3H]QNB) binding, respectively. [125I]alpha-Bungarotoxin binding was efficiently inhibited by alpha-bungarotoxin, nicotine, carbachol, and d-tubocurarine. [3H]QNB binding was competitively inhibited by atropine, pirenzepine, and carbachol. Hexamethonium did not affect the binding of either ligand. In competition experiments with [3H]QNB, pirenzepine recognized only one binding site with "low affinity," and carbachol recognized two sites with different affinities. beta-adrenergic receptors were present in a very low amount, whereas alpha-adrenergic and dopaminergic receptors were not detectable. IMR32 cells had an imipramine-sensitive [3H]dopamine uptake, but carbachol, high levels of K+, the calcium ionophore A23187, and alpha-latrotoxin were not able to induce release of [3H]dopamine that had been taken up. The ultrastructural analysis showed that IMR32 cells contained very few dense-core vesicles, suggesting a low storage capacity for neurotransmitter. These cells could be an useful in vitro model for studying neurotransmitter receptors of the human CNS.
Clementi
F
F
Cabrini
D
D
Gotti
C
C
Sher
E
E
D002038:Bungarotoxins; D002460:Cell Line; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D011813:Quinuclidinyl Benzilate; D011941:Receptors, Adrenergic / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011954:Receptors, Dopamine / Q000378:metabolism; D014316:Tritium / Q000378:metabolism
D002038:Bungarotoxins; D011941:Receptors, Adrenergic; D011950:Receptors, Cholinergic; D011954:Receptors, Dopamine; D014316:Tritium; D011813:Quinuclidinyl Benzilate; D004298:Dopamine