title: [Freeze fracture study of vesicle attachment sites during mediator liberation in spinal motoneuron synapses].
abstract: Freeze-fractured appearances of vesicle attachement sites (VAS) in presynaptic active zone were studied in the spinal cord of 4-aminopyridine (4-AP) treated and nembutalized rats. The VAS were classified into: type 1 containing no intramembranous particles, type 2 with particles around the edge of openings, type 3 containing several particles within the VAS. The application of 4-AP, which is known to enhance transmitter release, affected strikingly the total number of VAS (p less than 0.001) but not the proportion of the three types. The predominance of type 3 outside the active zone and its similarity to particle-loaded indentations possibly corresponding to coated vesicle formation, suggested that type 3 may represent endocytosis. It is likely that the remaining two types represent exocytosis.
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D005614:Freeze Fracturing; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D018377:Neurotransmitter Agents / Q000378:metabolism; D051381:Rats; D013116:Spinal Cord / Q000166:cytology*; D013570:Synaptic Membranes / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure
chemical_list: D000631:Aminopyridines; D018377:Neurotransmitter Agents
vernacular_title: Issledovanie metodom zamorazhi vaniia--skalyvaniia mest prikrepleniia puzyr'kov vo vremia osvobozhdeniia mediatora v sinapsakh spinal'nykh motoneĭronov.