title: Measurement of free intracellular calcium in the brain by 19F-nuclear magnetic resonance spectroscopy.
abstract: We report the first measurement of the free intracellular calcium level in an actively metabolising intact cerebral tissue preparation. To this end, we applied the recently developed 19F-nuclear magnetic resonance calcium chelator, 5,5'-F2-1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), in superfused cerebral cortical slices to give values for the intracellular Ca2+ concentration of 350 and 480 nM, at external calcium concentrations of 1.2 and 2.4 mM, respectively. Under both conditions, the intracellular Ca2+ concentration was increased by depolarisation using a high external K+ concentration. Interleaved 31P spectra showed that the presence of the 5FBAPTA had a deleterious effect on the metabolic state of the tissue with an external Ca2+ concentration of 1.2 mM, but normal viability was maintained using 2.4 mM.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002118:Calcium / Q000032:analysis*; D002540:Cerebral Cortex / Q000032:analysis; D002614:Chelating Agents; D004533:Egtazic Acid / Q000031:analogs & derivatives; D005461:Fluorine; D006168:Guinea Pigs; D009682:Magnetic Resonance Spectroscopy
chemical_list: D002614:Chelating Agents; D005461:Fluorine; D004533:Egtazic Acid; C039877:5,5'-difluoro-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium