title: Ca(2+) dynamics in synaptosomes isolated from the squid optic lobe.
abstract: Synaptosomes from the optic lobes of squid (Loligo forbesi) were prepared by homogenization and allowed to settle onto glass coverslips. Synaptosomes were loaded with Ca(2+) sensitive dyes (Fura-2 AM, Calcium Green-1 AM and Calcium Green-5N AM), visualized by light microscopy and Ca(2+) sensitive fluorescence signals recorded and analyzed. With Fura-2, resting Ca(2+) was found to be 80 nM (n = 10, SEM 5.7). Addition of K(+) (30 mM), caffeine (3 mM) and thapsigargin (10 microM) evoked transient increases in cytoplasmic Ca(2+). Addition of BAPTA-AM (20 microM) decreased intrasynaptosomal free Ca(2+). Similar results were obtained with Calcium Green-1 AM but not with Calcium Green-5N AM. We conclude that synaptosomes from the squid optic lobe posses intact membranes and mechanisms to regulate intrasynaptosomal free [Ca(2+)], as well as caffeine sensitive Ca(2+) stores. The results of this study are discussed with respect to the role of Ca(2+) in presynaptic protein synthesis.
authors: Departmento de Biofísica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
authors: J C
authors: JC
authors: Benech
authors: P A
authors: PA
authors: Lima
authors: J R
authors: JR
authors: Sotelo
authors: E R
authors: ER
authors: Brown
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D049832:Decapodiformes; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009899:Optic Lobe, Nonmammalian / Q000187:drug effects / Q000378:metabolism*; D009930:Organic Chemicals; D011189:Potassium Chloride / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000697:Central Nervous System Stimulants; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D009930:Organic Chemicals; C071336:calcium green; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D002110:Caffeine; D004533:Egtazic Acid; D011189:Potassium Chloride; D019284:Thapsigargin; D002118:Calcium