Neurobiochemical evidence for calcium-induced depolarization of EGTA-pretreated hippocampal synaptosomes.
The neurochemical effects of calcium were determined in hippocampal cholinergic synaptosomes which had been prepared and preincubated in calcium-free medium containing 50 microM EGTA. Calcium (and barium) reversibly stimulated [3H]acetylcholine release and produced a long-lasting elevation of high-affinity [3H]choline uptake. Both effects were blocked by omega-conotoxin and substantially reduced by tetrodotoxin. Together, these data indicate that calcium causes membrane depolarization and is associated with opening of voltage-gated sodium channels in EGTA-pretreated synaptosomes.
Vickroy
T W
TW
Department of Physiological Sciences, University of Florida, Gainesville 32610.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002794:Choline / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology*; D006624:Hippocampus / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; C053423:Conus magus toxin; D013779:Tetrodotoxin; D004533:Egtazic Acid; D002794:Choline; D000109:Acetylcholine; D002118:Calcium