Raj. Lester et Ja. Dani, TIME-DEPENDENT CHANGES IN CENTRAL NICOTINIC ACETYLCHOLINE CHANNEL KINETICS IN EXCISED PATCHES, Neuropharmacology, 33(1), 1994, pp. 27-34
The behavior of nicotinic acetylcholine receptor (nAChR) channels in a
cutely isolated habenula neurons was examined by rapidly applying nico
tinic agonists to outside-out membrane patches. At negative membrane p
otentials, applications of 100 mu M nicotine routinely produced macros
copic currents due to the opening of a large number of channels. Durin
g the continuous application of the agonist, the number of open nAChR
channels decreased exponentially, i.e. receptor desensitization. A pro
gressive loss in the number of channels contributing to the peak curre
nt was observed with time following outside-out patch excision, i.e. r
eceptor rundown. In addition to rundown there was a time-dependent inc
rease in the rate of desensitization and a concomitant slowing in the
rate of recovery from desensitization. The extent of rundown and the c
hanges in desensitization were coupled to the time after patch excisio
n and were not dependent on ligand activation of nicotinic channels.