title: The effect of non-quantal acetylcholine release on quantal miniature currents at mouse diaphragm.
abstract: 1. The amplitude and exponential decay time constant of miniature endplate currents (MEPCs) were measured in mouse diaphragms treated with anti-cholinesterase under conditions known to modulate non-quantal acetylcholine (ACh) release. 2. Anti-cholinesterase prolonged MEPC decay and the extent of this initial prolongation was not influenced by non-quantal release. When non-quantal release was present, the decays of MEPCs became increasingly faster over several hours. This increased decay did not occur in the absence of non-quantal release. 3. Potentiation of the non-quantal release by zero Mg2+ and 1 x 10(-5) M choline, on the other hand, led to acceleration of MEPC shortening. 4. Increase of temperature from 15 to 26 degrees C and the presence of the desensitization-promoting drug proadifen (5 x 10(-6) M) accelerated the rate of MEPC shortening. 5. These observations are consistent with increased receptor desensitization due to non-quantal release. Repetitive binding of ACh to postsynaptic receptors which prolongs the time course of MEPC in anti-cholinesterase-treated endplates leads to progressive desensitization in the presence of non-quantal release and to the subsequent shortening of the quantal responses.
authors.affiliation: Kazan Medical Institute, Russia.
authors.forename: R A
authors.initials: RA
authors.lastname: Giniatullin
authors.forename: R N
authors.initials: RN
authors.lastname: Khazipov
authors.forename: T I
authors.initials: TI
authors.lastname: Oranska
authors.forename: E E
authors.initials: EE
authors.lastname: Nikolsky
authors.forename: V A
authors.initials: VA
authors.lastname: Voronin
authors.forename: F
authors.initials: F
authors.lastname: Vyskocil
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002794:Choline / Q000494:pharmacology; D003964:Diaphragm / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D009045:Motor Endplate / Q000187:drug effects / Q000378:metabolism*; D009121:Muscle Denervation; D011335:Proadifen / Q000494:pharmacology; D013696:Temperature
chemical_list: D011335:Proadifen; D008274:Magnesium; D002794:Choline; D000109:Acetylcholine