Role of stored calcium in the regulation of neurotransmitter quantum size.
Release of stored calcium ions during activation of ryanodine receptors with ryanodine or caffeine elevates the mean amplitude of spontaneous miniature end-plate potentials. Blockade of these receptors with selective antagonists abolishes this effect. Preliminary loading of the motor nerve terminals with intracellular calcium buffer EGTA-AM, but not with BAPTA-AM, also completely prevented the ryanodine-induced increment of miniature end-plate potential amplitude probably induced by the release of stored calcium. Vesamicol, a selective blocker of acetylcholine transport into vesicles, prevented the ryanodine-induced increment of the mean amplitude of miniature end-plate potentials. This increment was 2-fold more pronounced after preliminary blockade of protein kinase C with chelerythrine and was completely abolished by blockade of protein kinase A with H-89.
Department of Human and Animal Physiology, Biological Faculty, M. V. Lomonosov Moscow State University, Moscow, Russia. oskiteva@gmail.com
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D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D053119:Benzophenanthridines / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D018680:Cholinergic Antagonists / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D055369:Miniature Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D010880:Piperidines / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D046509:Tissue Culture Techniques
D053119:Benzophenanthridines; D002413:Cations, Divalent; D018680:Cholinergic Antagonists; D007546:Isoquinolines; D010880:Piperidines; D019837:Ryanodine Receptor Calcium Release Channel; D013449:Sulfonamides; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D012433:Ryanodine; C006189:vesamicol; D002110:Caffeine; D004533:Egtazic Acid; C046770:EGTA acetoxymethyl ester; C016299:chelerythrine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D000109:Acetylcholine; D002118:Calcium