title: Extracellular calcium alters frequency modulation of [3H]acetylcholine release from rat hippocampal slices.
abstract: The concentration of extracellular Ca2+ has been shown to enhance or attenuate [3H]acetylcholine (ACh) release subsequent to a conditioning stimulus in rat brain hippocampal slices. Slices were incubated in vitro in [3H]choline solution. Subsequently the slices were subjected to two consecutive electrical stimulations separated by 15 or 30 min at 0.25, 1, 4 and 16 Hz and [3H]ACh release was assessed. It was found that a conditioning stimulus may reduce [3H]ACh release during a second stimulation. This phenomenon is frequency related and disappears when the two stimulations are 30 min apart. High extracellular Ca2+ (4.0 mM) further attenuated [3H]ACh release during the second stimulation, whereas low Ca2+ (0.32 mM) abolished the decrease in [3H]ACh release following the second stimulation in all frequencies tested.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000109:Acetylcholine / Q000493:pharmacokinetics*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D013779:Tetrodotoxin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000109:Acetylcholine; D002118:Calcium