Activation and desensitisation of acetylcholine release by zinc at Torpedo nerve terminals

Article Article scientifique Article Activation and desensitisation of acetylcholine release by zinc at Torpedo nerve terminals eng 1996-09 author Dunant Yves 25134 author Loctin Françoise 25826 author Vallée Jean-Paul 0000-0001-7546-2013 29185 Département de radiologie et informatique médicale (RADIO) author Parducz Arpad author Lesbats Bernard author Israël Maurice 853-858 10.1007/s004240050208 8772136 0031-6768 http://link.springer.com/10.1007/s004240050208 Treatment with 100 or 250 μM ZnCl2 irreversibly blocked neurotransmission in the Torpedo electric organ by inhibiting acetylcholine (ACh) release. In Zn2+-treated tissue, release failure did not result from impairment of Ca2+ entry since stimulation still provoked an accumulation of Ca2+. Also pretreatment of isolated synaptosomes with Zn2+ inhibited to the same extent the release elicited by KCl-evoked depolarisation and the release elicited by using the Ca2+ ionophore A23187. On the other hand, after application of A23187, Zn2+ by itself efficiently triggered ACh release from synaptosomes. This dual effect of Zn2+ was also observed to occur in proteoliposomes equipped with mediatophore (a protein of the presynaptic membrane characterised by its capability to support Ca2+-dependent transmitter release). Hence, Zn2+ mimicked two fundamental actions of Ca2+ on nerve terminals, which are: (1) the immediate activation of release, and (2) a more slowly developing desensitisation of release. Zn2+ was more powerful than Ca2+ for both actions. It is concluded that the dual action of Zn2+ on the mediatophore protein accounts at least in part for its complex effects on neurotransmission. Acetylcholine / metabolism Animals Calcimycin / pharmacology Calcium / metabolism Cholinergic Fibers / drug effects Cholinergic Fibers / metabolism Electric Organ / drug effects Electric Organ / physiology Female Male Potassium Chloride Proteolipids / metabolism Synaptic Transmission / drug effects Synaptosomes / drug effects Synaptosomes / metabolism Torpedo Zinc / pharmacology Torpedo electric organ Mediatophore Dewey 610 3 Faculté de médecine 2 false 286 Imagerie cardiaque fonctionnelle 541 Pflügers Archiv 432 5 65036d5e-f0b9-4de7-925d-79904303865c Article (Published version) Restricted Article-scientifique-from-crossref.pdf 778520 application/pdf baaa42496eada83a76489b2f48faf39f1e2bafc2e079ad6f4d5589615562e8d2 restrictedAccess Faculté de médecine

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Activation and desensitisation of acetylcholine release by zinc at Torpedo nerve terminals	Pflügers Archiv			1996	75	0

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