Calcium buffering capacity of neuronal cell cytosol measured by flash photolysis of calcium buffer NP-EGTA.
N1E-115 mouse neuroblastoma cells were injected with a calcium buffer/indicator solution to allow both ratiometric measurement of free calcium concentration and the release of calcium ions upon UV flash. The solution contained sulforhodamine, a marker dye used to estimate the volume injected; fluo-3, a calcium indicator, and NP-EGTA, a high affinity calcium-selective buffer that is converted by UV flash to products with negligible calcium affinity. The calcium increase recorded upon UV irradiation (Delta[Ca2+]i) was small for small injection volumes, increased with larger injection volumes, but approached a plateau at the largest injection volumes. From this relation we estimate the buffering capacity of the cytosol as 1700 ions bound per ion free.
School of Biomedical Sciences, University of St. Andrews, Fife, KY16 9AJ, Scotland.
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Fleet
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Ellis-Davies
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Bolsover
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D010782:Photolysis; D014407:Tumor Cells, Cultured
D002118:Calcium