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J Recept Res. 1991;11(6):1001-21.

Initial characterization of the nicotinic acetylcholine receptors in rat hippocampal neurons.

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Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201.


The properties of the neuronal nicotinic acetylcholine receptor in primary cultures of hippocampal cells from fetal rats (17-18 days gestation) were studied using the whole-cell patch-clamp technique in Na(+)-external, Cs(+)-internal and nominally Mg(2+)-free solutions. The nicotinic agonists acetylcholine, (+)anatoxin-a, and (-) and (+)nicotine all evoked inward whole-cell currents in hippocampal neurons that were voltage clamped near their resting potentials. Sensitivity to (+)anatoxin-a was first detected at around day 6, and thereafter the magnitude of the response increased as a function of number of days in culture up to about 40 days. The whole-cell current waveforms consisted of more than one peak whose relative amplitude depended on the agonist concentration. These currents were reversibly blocked by micromolar concentrations of d-tubocurarine, mecamylamine, and dihydro-beta-erythroidine. At nanomolar concentrations, neuronal bungarotoxin, alpha-bungarotoxin and alpha-cobratoxin caused an irreversible blockade of the currents but they were unaffected by tetrodotoxin, atropine, DL-2-amino-5-phosphonovaleric acid, Mg2+, and 6,7-dinitroquinoxaline-2,3-dione. In addition, the currents were also blocked in a reversible manner by methyllycaconitine at picomolar concentration. The current-voltage plots elicited by both (+)anatoxin-a and acetylcholine revealed larger inward currents and smaller or no outward currents. The present results demonstrate the existence of an inwardly rectifying, snake neurotoxin-sensitive functional nicotinic acetylcholine receptor ion channel in rat hippocampal neurons.

[Indexed for MEDLINE]

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