Brief-lifetime, fast-inactivating ion channels account for the alpha-bungarotoxin-sensitive nicotinic response in hippocampal neurons.
Single-channel currents underlying the various types of nicotinic receptor-gated whole-cell currents (previously termed IA, IB, II and III) were identified in rat hippocampal neurons. In response to applied acetylcholine (ACh), most of the neurons showed a fast-decaying whole-cell current (type IA) that can be blocked by alpha-bungarotoxin (alpha-BGT). In these neurons, a novel nicotinic receptor channel was found, having a conductance of 73 pS and an open time of 0.12 ms at -80 mV. This channel showed a fast concentration-dependent inactivation that had a time constant of 0.5 ms at 1 mM ACh. A high Ca2+ permeability and the involvement of alpha 7 receptor subunits in the channel structure were suggested.
Castro
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Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201.
Albuquerque
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002038:Bungarotoxins / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000187:drug effects*
D002038:Bungarotoxins; D007473:Ion Channels; D011978:Receptors, Nicotinic; D000109:Acetylcholine