title: Routes of acetylcholine leakage from cytosolic and vesicular compartments of rat motor nerve terminals.
abstract: Acetylcholine efflux at the rat neuromuscular junction was assayed following blockage of ACh transport into synaptic vesicles by 2-(4-phenylpiperidino) cyclohexanol (AH5183). [2H4]Choline was used as a labeled precursor. AH5183 completely blocked ACh efflux from the cytosolic compartment but had comparatively less effect on release from the unlabeled vesicular pool. Tissue [2H4]ACh levels increased after AH5183 addition due to cytosolic ACh retention. Thus, ACh in the non-vesicular pool (calculated to be 34% of the total ACh) may efflux solely via the AH5183-sensitive ACh transporter inserted into the terminal membrane. ACh released from the vesicular fraction was about 100-fold more than could be accounted for by miniature end-plate potentials; possible causes of this overestimate are discussed.
authors.affiliation: Department of Physiology, University of Wisconsin, Madison 53706.
authors.forename: D O
authors.initials: DO
authors.lastname: Smith
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007700:Kinetics; D009046:Motor Neurons / Q000378:metabolism*; D009132:Muscles / Q000294:innervation; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism
chemical_list: D009467:Neuromuscular Depolarizing Agents; D010880:Piperidines; C006189:vesamicol; D000109:Acetylcholine