title: Failure of the calcium channel activator, Bay K 8644, to increase the release of acetylcholine from nerve terminals in brain and diaphragm.
abstract: The calcium channel activator Bay K 8644 did not increase the release of acetylcholine from rat brain cortex prisms incubated in the presence of 3 mmol l-1 or 25 mmol l-1 K+ nor from rat diaphragms incubated in the presence of 5 mmol l-1 or 25 mmol l-1 K+. It also did not influence the release of acetylcholine from cortex prisms incubated in the presence of 25 mmol l-1 K+ and of lowered concentrations of Ca2+ ions. It is concluded that the voltage-dependent Ca2+ channels in the nerve terminals, responsible for the depolarization-induced influx of Ca2+ ions into the nerve terminals and thus for the depolarization-evoked release of acetylcholine from the nerve terminals, are different from the voltage-dependent Ca2+ channels in the heart and smooth muscle cells.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011188:Potassium / Q000502:physiology; D051381:Rats; D012132:Respiratory Muscles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000109:Acetylcholine; D011188:Potassium